Zoom (sent to registered delegates) (Hosted virtually by the AfLS & AfPS)
Zoom (sent to registered delegates)
Hosted virtually by the AfLS & AfPS
*** Note : The time zone of the web page is controlled by you as an Indico Setting (top right) ... set your location to see local times
*** So in Central African Time, all sessions start 15:00 CAT.
Joint virtual Workshop Event for the The African Synchrotron Light Source (AfLS2020)
and the African Physical Society (AfPS2020)
towards a brighter future
The AfLS3 and the AfPS2020 were due to be held in Kigali, Rwanda, from 16th - 21st November 2020. However, due to the current COVID-19 global scenario, this is postponed provisionally to AfLS3 from 15th - 20th November 2021.
We now present the AfLS2020 - AfPS2020 Virtual Workshop with a restricted agenda from the 18th- 20th November. This site focusses on the AfLS2020 event, with the AfLS2020 / AfPS2020 overlap. For the AfPS2020 websire, please go here.
During the AfLS1, the roadmap towards the ultimate establishment of an AfLS was developed, together with a Steering Committee which had both a large African and global footprint. The Roadmap relates to developing the user base, the projects, deep capacity building, promoting networks, scientific and technical exchanges, building associated local infrastructural capacity, raising the profile of the project politically and developing the Pan African strategic plan with African leadership. AfLS2 built on these foundations, in particular, developing the Pan-African and socio-political aspects, while the science and the motivation grew ever stronger.
Zoom Screen shot of delegates and Presentation Videos stored on on YouTube
The African LightSource virtual workshop will review the light source based science and further progress the vision of an African Light Source. This conference will cover topics that include Medical Sciences, Heritage Sciences, Geosciences, Environmental sciences, Energy Sciences, Nano Sciences, Materials Sciences, Mineral Sciences, Accelerator and Detector Sciences, Competitive Industry, Capacity Building and Infrastructures. There will also be sessions on the strategy and vision for an African light source. Details on the AfLS project are here.
Participants will be African scientists and students, and also the international colleagues, who have conducted research related to or enabled by the crystal state of matter, and also research enabled by modern Light Sources. The strategic components of both conferences includes policy-making sessions.
Both English and French speaker African scientists are welcome to attend the conference. The conference will be in both languages (English and French), even though most presentations and discussions will be in English.
The programme is available from the Programme link in the left hand menu. The programme details, as they are updated, are available in the Timetable link on the left hand menu.
Students and Early Career Scientists welcome
Students and Early Career Scientists who would like to attend should register and in addition apply for support for on-line data using the link in the left panel.
All languages are welcome to attend the conference (the conference can be both in French and English as international languages).
The AfLS3 conference is supported by:
For more information on sponsorship, contact the organising committee by mail at email@example.com. Various sponsorship packages available.
African Tradition : The AfLS ceremonial Calling stick and Speaking stick10m
The AfLS African ceremonial calling stick summons us from around the world to participate in this historic Event.
From within Africa, it fist called us, in 2015, to AfLS1 in Grenoble in November 2015. It was there throughout the proceedings. Then it next called us back to its home country, to Ghana, in January 2019, for AfLS2. From there it called us to Rwanda, for AfLS3, which was to be held at this very time. However, due to the pandemic, it has now called us instead to this Virtual Workshop, AfLS2020.
The AfLS ceremonial calling stick from ancient Ashanti culture. Normally, it would be planted at a nexus of roads, where all would pass and note its message boards. For the AfLS, the message is the vision of an Advanced Light Source in Africa, pumping out new scientific discoveries, of great relevance to Africa, and also the world. Realizing this vision, means Africa is well on the road to being a knowledge-based economy and a font of innovation.
The stick has the gravitas of a sceptre. It depicts both genders equally Symbolically we have, inclusivity, and ubuntu. All are invited, and all will build the AfLS together.
At the end of these proceedings, it will call us again to Rwanda, in November 2021, for the rescheduled AfLS3
The calling stick final resting place is the future AfLS facility, where it will still call all people to its campus.
The AfLS African ceremonial speaking stick, is used throughout the conference to endow, in the African tradition, each speaker in turn, with authority and wisdom to speak. The Speaking stick is handed over by the Session Chair to each next speaker, before they commence, and they return it to the chair as they leave. We use the moment of transfer for each official photograph of the speaker.
The AfLS speaking stick will be displayed at the future AfLS facility.
(Department of Physics, University of Pretoria), DrProsper Ngabonziza
(Max Planck Institute for Solid State Research), Prof.Simon Connell
(University of Johannesburg), Prof.Tabbetha Dobbins
The African Light SourceProject10m
The most transformative mega-research entity is surely the modern light source. Research is both fundamental and applied. Both streams lead to innovation, competitive industry, the solution of problems of particular relevance for Africa, high end human capacity development, building the culture of learning, the inspiration of young learners to greater efforts and building a new generation of competent and enabled youth. There are other aspects, such as science diplomacy, pan Africanism, the globalisation and democratisation of participation in new knowledge generation, the implication that the large scale research infrastructure is fed by a healthy regional and national capacity in terms of human and equipment infrastructure. The passionate belief in this positive role for mega-science in society has driven the momentum towards the African Light Source. The call was first sounded in 2002, and it has been repeated by many sources on many platforms. African scientists are strongly participating in research exploiting the power of modern light sources, both from within African institutions, and from other institutions, as the exercise of the African science diaspora. In addition, the global science community has also strongly supported the global proliferation of the benefits of access to large-scale research infrastructures, and to extending the collaborative participation totally. This combination of African and International leadership towards an African Light Source is embodied in the project for a Light Source in Africa. These COVID times have seen the Light Source designated as an essential service, remaining open during lockdown, as the front-runner in the fight against this greatest scourge of our decade. Indeed, we would like to see Africa extend its already significant contribution, to combating this disease, and especially others of particular relevance to Africa. This contribution details the progress on the Roadmap towards the African Light Source, and outlines the future projects, many of which will be discussed further in this meeting.
(University of Johannesburg)
The African Physical Society10m
African Strategy for Fundamental Physics and Applications Launch15m
DrKetevi Adikle Assamagan
(Brookhaven National Laboratory)
Address : The Honorable Minister : Environment, Science, Technology & Innovation10m
(The Ghanain Government)
Syncroton Radiation-based X-Ray study on energy storage materials: a case for hematite.30m
The conventional laboratory characterization techniques provide limited information to better understaning of materials for different optoelectronic applications. In particular, understanding electrochemical mechanisms of materials suitable for energy storage may result in better solutions to the global energy crisis. Synhroton radiation has very high brilliance and broad energy range in the electromagnetic radiation, from far-IR through to hard X-Ray region. The recent availability of synchroton radiation facilities is driving technical and theoretical advances in scattering and spectroscopic techniques over the last few decades. These advances in synchroton based characterization techniques have made it possible to study the underpinning issues in thin films and nanostructured materials used in energy storage devices. An electrochemical roadmap based on much more knowledge-driven approach can be drawn by utilizing synchroton based element specific spectroscopic and scattering techniques. This work presents recent developments in the optimization of materials for efficient energy storage using synchroton radiation.
(University of Pretoria)
AfLS2020 Session :: Invited Talks
(Canadian Light Source)
Understanding the effect of changing environmental conditions on vital soil processes30m
(University of California, Merced)
The AfLS CDR Process and Status30m
The Conceptual Design Report (CDR) is an important founding document for any large scale research infrastructure. In the case of the African Light Source (AfLS, we will have a CDR with four volumes:
* Volume I. Political, Economic Development and Management Concepts
* Volume II. Machine Design Concepts
* Volume III. Scientific Cases and Technical Capabilities
* Volume IV. Integrated Site Design and Construction
The spirit of the document is community consultation, and it will ultimately be written by experts, including those from the global community. It is Africa owned, and exhibit the spirit of Ubuntu.
This presentation has two parts. In the first we describe the CDR Document, and look at its sections, their intentions and target audiences.
We then lay out the CDR Roadmap process including the community consultation in virtual workshops by subject area, to elicit many White Papers, especially for the scientific case. The the process unfolds as to the mechanism of managing the vision and quality, as well as coherence of the CDR document.
Following this we will describe the work done so far on the White Paper for Volume II as an example. This Volume deals with the machine aspects, and contextualises this discussion against international developments.
AfLS2020 Session :: African Initiatives towards the AfLS
(University of Johannesburg)
Lightsources for Africa, the Americas, Asia and Middle East and the Pacific (LAAAMP)12m
We describe an initiative funded by a 3-year, 300K-Euro grant from the International Science Council (ISC) to the International Union of Pure and Applied Physics (IUPAP) and International Union of Crystallography (IUCr) in collaboration with over 30 partner organizations that include 16 advanced light sources to enhance the utilization of advanced light sources and crystallography in six targeted regions of the world, namely Africa, the Caribbean, Mexico, Southeast Asia, Middle East and the Pacific. LAAAMP’s programs include the development of a Strategic Plan for each region; a Colloquium program that sends experienced light source and crystallography users to those regions; establishment of crystallography training schools; design and distribution of a Brochure that describes advanced light sources and crystallography for government officials and the public; 2-month Faculty-Student (FAST) Team training visits to advanced light sources; and a sample mail-in program for data acquisition at advanced light sources. Finally, we discuss the path forward for LAAAMP.
(International Union of Crystallography)
The X-TechLab x-ray techniques platform in Bénin12m
Towards an African Crystallographic Association12m
BioStruct-Africa: empowering Africa-based scientists through structural biology knowledge transfer and mentoring - recent advances and future perspectives12m
Being able to visualize biology at the molecular level is essential for our understanding of the world. A structural biology approach reveals the molecular basis of disease processes and can guide the design of new drugs as well as aid in the optimization of existing medicines. However, due to the lack of a synchrotron light source, adequate infrastructure, skilled persons and incentives for scientists in addition to limited financial support, the majority of countries across the African continent do not conduct structural biology research. Nevertheless, with technological advances such as robotic protein crystallization and remote data collection capabilities offered by many synchrotron light sources, X-ray crystallography is now potentially accessible to Africa-based scientists. This leap in technology led to the establishment in 2017 of BioStruct-Africa, a non-profit organization (Swedish corporate ID: 802509- 6689) whose core aim is capacity building for African students and researchers in the field of structural biology with a focus on prevalent diseases in the African continent. The team is mainly composed of, but not limited to, a group of structural biologists from the African diaspora. The members of BioStruct- Africa have taken up the mantle to serve as a catalyst in order to facilitate the information and technology transfer to those with the greatest desire and need within Africa. BioStruct-Africa achieves this by organizing workshops onsite at our partner universities and institutions based in Africa, followed by post-hoc online mentoring of participants to ensure sustainable capacity building. The workshops provide a theoretical background on protein crystallography, hands-on practical experience in protein crystallization, crystal harvesting and cryo-cooling, live remote data collection on a synchrotron beamline, but most importantly the links to drive further collaboration through research. Capacity building for Africa-based researchers in structural biology is crucial to win the fight against the neglected tropical diseases, e.g. ascariasis, hookworm, trichuriasis, lymphatic filariasis, active trachoma, loiasis, yellow fever, leprosy, rabies, sleeping sickness, onchocerciasis, schistosomiasis, etc., that constitute significant health, social and economic burdens to the continent. BioStruct-Africa aims to build local and national expertise that will have direct benefits for healthcare within the continent.
(Biostructafrica), Emmanuel Nji
(University of Stockholm, Sweden)
African Neutron and Synchrotron Data Analysis Competency - ANSDAC12m
(University of Cape Town)
African Synchrotron Network for Advanced Energy Materials12m
New materials for the capture of light and mechanical energy can potentially enable low-cost and innovative renewable sources of energy while eliminating negative effects on the environment that are inherent when non-renewable sources of energy are utilised. Energy materials characterisation with synchrotron x-rays is a vital tool for the development of modern and next generation energy harvesting and storage technologies. The advent of the first African Light Source (AfLS) has the potential to transform the energy materials and related technology industries that underpin a robust and sustainable economy. The ASNAEM project aims to expand the local knowledge base and build capacity in the existing synchrotron community in preparation for the AfLS. It will enable sustainable partnerships that extend beyond the lifetime of the project. In this talk, I will discuss the activities of the ASNAEM project and our vision for synchrotron science at the AfLS.
(University of Southampton)
GCRF START – Synchrotron Techniques for African Research12m
Prof.Bryan Trevor Sewell
(University of Cape Town)
Crystallography in Africa: the IUCR-UNESCO Africa Initiative12m
Crystallography is a science at the crossroads of physics , chemistry , geology, biology and material science .This involves therefore many researchers from all disciplines and then allows a general scientific life and network . Crystallography is involved in mining, material ,chemical , pharmaceutical industries. X-ray Crystallography is an important user of SR .Then it is very important to develop this science in sub-Saharan Africa. In 2014, for the International Year of Crystallography, the International Union of Crystallography (IUCR, www.iucr.org , Profs G. Desiraju and C. Lecomte) together with UNESCO ( Prof Nalecz , Dr JP Ngome) have started an ambitious program called IUCR-UNESCO Africa Initiative to promote crystallography teaching and research. This talk will introduce the Initiative: crystallography equipment for universities , schools ,open/ travelling labs .
(CRM2 University of Lorraine)
The African Materials Research Society12m
(Botswana Inst for Technology Research and Innovation)
Palaeontology enabled by Light Source studies30m
(University of the Witwatersrand)
AfPS Session: Invited talks
Please see Friday for Posters
Please go to the Friday Poster Session to view / download Posters / Slides.
(Brookhaven National Labs)
Letters of Support and Light Sources Roundtable5m
This seminal session has two parts.
Part 1 will launch and premiere the Letters of Support for the AfLS, received from Institutions and light sources, world wide. Also included are the MoUs and MoAs concluded so far. The AfLS is both an organisation and a broad umbrella for organisations that all share a vision of the AfLS.
Part 2 will be an opportunity for Directors of selected Light Sources to showcase their facilities, its scientific highlights and also, to use the opportunity to pass on wisdom and advice. The Light Source Directors will consider questions, and can answer them as a coherent collective, or in their own way. The questions are:
1 - What were the important arguments motivating a light source for your facility ?
2 - How was government(s) and the community engaged ?
3 - Why did you pick the design you have ?
4 - What are you best highlights of research ?
5 - How has it boosted the scientific community ?
6 - How has it boosted capacity building, competitive industry, asociated science park formation, economic competitiveness ?
(Brookhaven National Labs)
ESRF - The Light Sources Round Table11m
The story of the ESRF, highlighting its role in science and building the community followed by words of wisdom and advice, to pass on to the AfLS.
The story of Elettra, highlighting its role in science and building the community followed by words of wisdom and advice, to pass on to the AfLS.
ALBA and LEAPS - The Light Sources Round Table11m
The story of ALBA, highlighting its role in science and building the community followed by words of wisdom and advice, to pass on to the AfLS. The role of LEAPS for Africa and the AfLS is also presented.
Diamond - The Light Sources Round Table11m
The story of Diamond, highlighting its role in science and building the community followed by words of wisdom and advice, to pass on to the AfLS.
(Diamond Light Source)
SESAME - Light Sources Round Table11m
The story of SESAME, highlighting its role in science and building the community followed by words of wisdom and advice, to pass on to the AfLS.
The structural biology landscape in South Africa: what role do synchrotrons play in African science?30m
(National Institute for Communicable Diseases)
AfPS Session: Invited Talks
AfLS2020 and AfPS Joint Session: Invited Talk and Closing
(Massachusetts Institute of Technology & Brookhaven National Laboratory& African Laser Centre)
The Launch of the AfLS International Advisory Committee - AfLS IAC15m
AfLS3 - The 3rd AfLS Conference in Rwanda10m
(Max Planck Institute for Solid State Research)
The Three Wise Sages15m
We close with comments summing up the conference and providing leadership and vision for the future.
Three wise sages have been selected to share their thoughts.
All sages have attended the entire conference - aware of their role at the close of the conference. Each sage represents a different community and perspective.
1st Sage : A senior person.
2nd Sage : A woman.
3rd Sage : A young person.
Repository - AfLS Poster / Slides - Click on the Blue area - Click on the "View Contribution List" - visit the contribution by clicking on it, you will be taken to the Abstract ... on the right is the Poster / Slides, so you can click on them
Delegate poster / slide repository
A comparative study of two polymorphs of L-aspartic acid hydrochloride1h
Two polymorphs of l-aspartic acid hydrochloride, C4H8NO4+Cl-, were obtained from the same aqueous solution.Their crystal structures have been determined from singlecrystal data collected at 100 K. The crystal structures revealed
three- and two-dimensional hydrogen-bonding networks forthe triclinic and orthorhombic polymorphs, respectively. The cations and anions are connected to one another via N—H...Cl and O—H...Cl interactions and form alternating
cation–anion layer-like structures. The two polymorphs share common structural features; however, the conformations of the l-aspartate cations and the crystal packings are different. Furthermore, the molecular packing of the orthorhombic polymorph contains more interesting interactions which seems
to be a favourable factor for more efficient charge transfer within the crystal.
AC Analysis of Synthesized Nanofluids from Palm Kernel Oil for Transformer Insulation1h
The work presented in this paper revealed the effect of insulating (Al2O3) and semiconductive (TiO2) nanoparticles on green alternative insulating methyl ester oil synthesized from palm kernel oil. It also investigates the optimal concentration of the nanoparticle for dielectric improvement. The nanoparticle was functionalized with oleic acid before dispersion into the methyl ester to modify the stability of the mixture. The characterization of the nanoparticles was done using Scanning Electron Microscopy coupled with electron dispersive X-ray analysis (EDX). The nanofluids were prepared by dispersing 0.2, 0.4, 0.6, 0.8 and 1wt% of nanoparticle into the methyl ester. The effect of this nanoparticles on loss tangent, conductivity and AC breakdown voltage of the synthesized methyl ester was done, analyzed and compared. It was observed on both sides of nanoparticle that the loss tangent and conductivity reduces with an increasing concentration of nanoparticles. The AC breakdown result was analyzed with Weibull statistical tools and it was observed that the loading of both nanoparticles increases the characteristic AC breakdown strength of methyl ester with an optimum performance at 0.6wt%. The result revealed that Al2O3 nanofluid possesses the highest dielectric properties with low loss, low conductivity and high characteristic breakdown strength. The obtained results for both nanoparticles are promising because of improvement in dielectric properties with a noticeable one for Al2O3 nanofluid.
DrAbubakar Abubakar Khaleed
(University of Pretoria), MrSamson Okikiola Oparanti
(Ahmadu Bello University Zaria)
Bio-mimicry of photonic multi-scaled architectures of butterfly wing1h
In view of the rising interest in biomimicry within the Scientific & Engineering global communities, approaching nature, the STI community is inspired to copy from the numerous creatures which exhibit peculiar multi-functionalities & adaptation in achieving versatile performances. Natural nanostructures such as those on butterfly wings have the general characteristic of being multifunctional and energy-chemical elements.
In view of the established effective thermal management of the butterfly capabilities as demonstrated in several publications, the inner ring of the ocellus on the Caligo Memnon was examined. In the quest to unravel the usefulness of the black part, the authors carefully examined the nanostructures of the scales with various techniques. The analysis of the nanostructures give an indication of the factors associated with light absorption in the black part of the ocellus. Further examinations under optical studies point to the presence of pigment contributing to the blackness on the ocellus.
Indeed, biomimicking such nanostructures are useful in the design of oval cost-effective materials for use in applications where weight & cost are limiting factors.
(UNESCO UNISA ITLABS-NRF Africa Chair in Nanosciences & Nanotechnologies)
Construction and Characterization of Photodiodes prepared with Bi2S3 Nanowires1h
This work discloses the characteristics of a Bi2S3 nanowire / ITO photodiode and a manufacture method thereof; wherein, the high-crystalline Bi2S3 nanostructures were prepared by an environmental friendly dip-coating method onto Indium-doped Tin Oxide (ITO) coated glass substrates using bismuth nitrate and thiourea as raw material with DMF as solvent. The XRD spectra showed that the Bi2S3 nanowire exhibits orthorhombic structure, while the SEM images revealed the formation of uniform sized nanowires with diameter around 15.8 nm. The optical bandgap of the films had been estimated via Tauc plot and found to be in the range of 1.85 eV - 1.9 eV. In order to understand the I-V characterizations of the prepared diode showed prominent photo-response with a high photo-responsivity of 1.7 μA with a fast response time were reported in detail.
(University of South Africa)
Démarche pour le contrôle thermique d’un nanosatellite1h
Il est toujours connu que les nanosatellites disposent de la plus petite taille de l’enveloppe, un coût bas, avec un temps de développement le plus court. En effet, c’est une nouvelle forme miniaturisée des satellites conventionnels et l’une des formes les plus recherchées.
Pourtant, ils font face à différents problèmes à savoir les gradients thermiques élevés ou les différentes charges thermiques provenant des rayonnements solaires et des émissions infrarouges planétaires. La prédiction du comportement thermique se fait presque par simulation. Ce dernier doit être bien exécuté afin d’obtenir des résultats fiables en tenant compte de tous les paramètres qui régissent l’environnement spatial, à savoir le vide et le rayonnement des sources d’énergie élevée.
Les charges thermiques externes couplées à la dissipation thermique interne provoquent les effets les plus défavorables de la structure compacte des nanosatellites, et qui jouent un rôle incontournable dans la production d’une chaleur excessive, en particulier pendant les heures de haute chaleur. Pour cette raison, le contrôle thermique des nanosatellites et en particulier le contrôle passif, qui est principalement effectué pour maintenir tous les sous-systèmes ainsi que les composants de la charge utile dans les limites de température spécifiées, reste l’une des solutions les plus réalisables à apporter.
Le présent document vise à décrire les différents types de rayonnement thermique que subit le nanosatellite, puis à les simuler avec précision. L’impact sur l’ensemble du vaisseau spatial apparaît clairement lorsqu’il est en orbite et lorsque des paramètres changent tels que l’émissivité et l’absorptivité qui font référence aux revêtements optiques des matériaux
Il faut noter que pour la simplicité de la démarche, une forme simple du nanosatellite a été considérée. L’approche réalisée était un premier pas pour obtenir des résultats tangibles tout en envisageant une géométrie plus complexe et plus complète du nanosatellite à l’avenir.
(Faculty of science)
Ferrophotovoltaic properties of PZN-4.5PT nanoparticles thin films1h
Ferroelectric photovoltaics has been known for 50 years, it was not investigated extensively due to the low power conversion efficiency. Thus, we have very limited knowledge of ferroelectric materials and the underlying PV mechanism. Remarkably, recent research on the ferroelectric PV cells shows that engineered domain walls can exhibit a photovoltaic effect with an impressively high voltage output. The internal electric field in the ferroelectric material is one order of magnitude larger than conventional p-n or hetero junction solar cells . Despite their excellent properties, one of the greatest difficulties to integrate widely such materials in electronic devices is to achieve them in thin films form because of their incongruent melting property . In our recent studies we fabricate successively such thin films using the perovskites nanoparticles dispersed on a gel and deposited on silicon substrate conserving their ferroelectric properties.
In this work, we present a new generation of photovoltaic cells based on perovskite materials. Different parameters affect the performances of this cells such as architecture, the type of material used for the active layer, the techniques of fabrication and preparation of different layers. Thus we developed PZN-4.5PT and PZN-4.5PT + 1 % Mn nanoparticles thin film and show that these thin films could be used in photovoltaic and photoferroelectric applications. Different technics and methods were used to characterize them.
(Assane seck University of Ziguinchor)
Halogen and non-metals defects induced n- and p-type conductivity in monolayer MoS2 two-dimensional semiconductor1h
Recent developments from the doping of two-dimensional (2D) monolayer MoS2 has opened up the possibility of scaling down the thickness of semiconductors channel field-effect transistors to the sub-nanometer scale. In order to realise efficient MoS2 based devices including p-n junction and field-effect-transistor for optimal performance, a controlled doping system needs to be fully understood.
In this report, a systematic effective method of doping in order to realise a p- or n-type conductivity in monolayer MoS2 was predicted using density functional theory with the aid of the generalised gradient approximation. The structural, electronic and magnetic properties of halogens and group V atoms substitution, interstitial and vacancy-complexes of monolayer MoS2 were investigated. While the substitutional and vacancy complexes are more energetically favourable under the Mo-rich chemical potential conditions, the interstitial do not have preference for any chemical potential limit conditions. The substitutional defects are more energetically favourable than the interstitial in both the Mo-rich and S-rich chemical potential conditions. Whereas the group V substitutional defects are good candidate for p-type conductivity, the halogen substitutions are good candidate for n-type conductivity. The substitution of the group V and halogen atoms induced spin polarisation in the host with a total magnetic moment of 1.00 μB. The defect complexes are stable with respect to their binding energies. While the vacancy-complexes formed by VS and NS, PS, AsS behave as p-type semiconductors, those formed by the SbS and BiS exhibit metallic characters.
In addition to providing useful hint for device fabrication where spin polarisation are required, the results presented here could paved the way for more insight to realising enhanced p and n-type conductivity of defective monolayer MoS2 2D semiconductor
(University of Pretoria)
Influence of side-groups on the non-equilibrium dynamics of semi-crystalline polymer films1h
Combining different polymers lead to a wide range of phase behavior. At rapid processing conditions (during preparation or flow), polymers are squeezed/deformed at various length scales and exhibit significantly different properties. The extent of deformation and the variation in properties depend on how the polymer responds to such rapid processing conditions and is related to the molecular details of the polymer. Molecular architecture, composition, and molecular size control polymer–polymer phase characteristics.Binary mixtures and diblock copolymers exhibiting macrophase separation and microphase segregation are concepts that are fairly well understood at the moment. The study uses dewetting experiments on non–equilibrium semi–crystalline polymer films to investigate the inter-relationship of structure and visco-elastic behavior. At higher dewetting temperatures, it is worth investigating why isotactic poly(para-methylstyrene) (iPpMS) films have exhibited a decrease in dewetting velocity with increase in temperature.
Paineira beamline for time-resolved and high resolution X-ray diffraction experiments at Sirius1h
The Paineira beamline is optimized for powder diffraction with combined spectroscopy techniques and is aimed at the structural characterization of polycrystalline materials under operando working conditions. The talk will briefly cover the fundamental parameters of the Sirius storage ring, the 1st phase beamlines currently under commissioning and finally a brief overview of the Paineria beamline and its capabilities
Plasmonic refractive index sensitivity of silver nanoparticles with graphene coatings layers used for LSPR biosensor applications1h
A new hybrid graphene layer structure of the resonance of localized surface plasmon (LSPR), with silver nanoparticles (AgNPs) and substrate has been proposed to obtain a broadband absorption response for plasmon biosensors. The resonance peaks in the absorption spectra of the nanostructure SiOx/AgNPs/Graphene, demonstrate significantly different profiles such as the thickness of the graphene, and the refractive index of the surrounding environment which is, gradually, diverse. Numerical simulation reveals a shift in plasmon resonance peaks which result from coupling between the AgNPs networks and the covering graphene layer. In addition, the LSPR modes swing to red from 412 nm to 548 nm when the thickness of the graphene layer deposited on silver nanoparticles changes from 0.34 nm to 9 nm. We have found that the LSPR modes can lead to an improvement in terms of sensitivity to a deposit of a graphene layer. While being sensitive to variations of the graphene layer with the incidence wave normal to the substrate and leading to a gain of 304.60% (4.04 times) when the pure AgNPs conventional biosensor was coated with graphene layer of the 9 nm. These characteristics should make these biosensors a choice preferred for biosensors applications, compared to other contemporary biosensors.
(Laboratory of Advanced Materials Studies and Applications (LEM2A), Physics Department, Faculty of Science, Moulay Ismail University of Meknes, B.P.11201 Zitoune Meknes, Morocco.)
Pulsed laser ablation in liquids: an efficient approach for nanofluids fabrication1h
Nanofluids are advanced kind of liquids or heat transfer fluids mixed with a small concentration of nanometer-sized solid particles in suspension. Nanofluids have broad applications in industries where efficient heat transfer fluids are crucial for cooling or heating processes. In addition, the shortage of fossil fuels motivated researchers to use alternative energy sources such as solar energy, particularly, the Concentrating Solar Power (CSP) which is based on thermal energy conversion. Therefore, it is critical to enhance the efficiency and performance of the solar thermal systems by using highly stable, cost effective and efficient nanofluids. The aim of this contribution is the investigation of a nanofluid consists of copper nanoparticles nCu and Ethylene Glycol (EG) which has been made by a one-step method known as pulsed Nd:YAG laser ablation in liquids. In this method, pure copper target was ablated in the presence of EG under ambient conditions to form nCu-EG nanofuid. Structural and morphological analysis confirmed the successful ablation of the Cu target in EG, and spherical Cu nanoparticles were obtained. Thermal conductivity analysis of nCu-EG nanofluid revealed an enhancement in thermal conductivity of about 22.74%. These results confirmed that pulsed Nd:YAG laser ablation of a Cu target in EG could be a suitable method for the fabrication of efficient nanofluids for solar thermal engineering systems.
(* UNESCO UNISA ITLABS-NRF Africa Chair in Nanosciences & Nanotechnoly(U2ACN2), NANOsciences AFrican NETwork (NANOAFNET), University of South Africa Physics Department)
Radiation-induced defects on pulsed laser deposited VO2 thin films1h
A growing interest in the development and use of small satellites in interplanetary missions with more up to date technologies is becoming a considerable option than large conventional satellites. Future development of these small satellites will require the application and use of passive thermochromic layers to achieve good thermal control for longer mission life and cost-effective launches. Vanadium dioxide (VO2) thin films present an imminent prospect as a passive smart radiator device (SRD) for thermal control management in nano and microsatellites. The thermochromic response of VO2 based SRDs is channeled by low emissivity at lower temperatures to preserve the heat, and high emissivity at high temperatures to fritter away the additional unnecessary heat. Different radiation species in a space environment interacts with materials, and induce properties modifications in different ways. Hence; VO2 coatings need to demonstrate deep-space radiation tolerance based on their structural, electronic, and electrical properties. This review article provides a focussed overview of the radiation response and phase transition characteristics of VO2 thin films subjected to gamma rays, neutrons, and magnesium ions with energy and projectile doses similar to those accosted by spacecraft. A broad overview of the radiation effects and their interaction mechanisms on pulsed laser deposited VO2 thin films.
DrItani Given Madiba
(University of South Africa)
Radiological Assessment of cement particles from Obajana Factory1h
Massive building constructions result to high demand of cement production in recent time. This lead Obajana cement plant to operate at maximum capacity in Nigeria. Exposure to high level radiation for prolong period can result to acute health effects such as skin burns, cancer and cardiovascular disease. This study evaluates the natural radionuclides and radiological indices of cement particles from productions plant of Obajana Factory. Gamma ray spectroscopy was used to analyze the activity level of 226Ra, 232Th and 40K in the samples. The activity concentration of the sample ranged between (7.4719±1.9179 – 60.1351±8.5508) BqKg-1, (29.4892±1.1009 – 90.1191±6.2124) BqKg-1 and (84.8930±3.8076 – 179.3318±11.4227) Bqkg-1, with the average value 36.0011±17.5529 Bqkg-1, 49.2077±21.1908Bqkg-1, and 146.6098±45.0115 Bqkg-1 for 40K, 226Ra and 232Th respectively. The activity concentrations of 226Ra and 232Th were slightly above the corresponding world average concentration of 32 BqKg-1 for 226Ra and 45 BqKg-1 for 232Th. The high concentration might be attributed to material composition used for cement production in Obajana Cement Factory. The average values of Absorbed dose (D), Annual effective dose rate (H), Annual gonad dose equivalent (AGDE) and Excess lifetime cancer risk (ELCR) are 53.303 nGy-1, 0.065 mSv, 363.961 mSvy-1 1.928 x10-3 respectively. The absorbed dose and annual gonad dose equivalent were lower than the world standard of 60 nGy-1 and 1.0 mSv respectively, while the Annual gonad dose equivalent (AGDE) and Excess lifetime cancer risk (ELCR) were slightly above the world standard of 300 mSvy-1 and 0.29 x10-3 respectively. The average value of External and Internal hazard indices (Hex and Hin) were below world standard of unity. The radiological assessment from this research compared favorably with other related published studies and world permissible limits, therefore constitute no radiological risk.
DrIbrahim Ayodeji Bello
(Ahmadu Bello University Zaria Nigeria)
Rheological behaviour of residues in dry anaerobic digestion performed by Vane geometry1h
The knowledge of the rheology of residues involved in dry digestion is an essential factor for process optimization. Despite this fact, it is difficult to characterize the rheological behaviour of these residues with high total solid (TS) content. Indeed, the standard methods of rheological measurements are poorly adapted to these residues because of the sliding effects observed during the measurements. In this study, we used a non-standard method, the Vane geometry, for its particularity to limit the sliding effects. Two types of measurements were carried out on potato residues of 18 to 35% TS, extracted from the digesters. The first measurement was to submit to the sample a rising shear velocity ramp from 0 to 200 s-1 at 37°C and 55°C. The results of these measurements show a good correlation between the rheograms and Herschel-Bulkley model and we deduced a rheofluidifying threshold behaviour. The second measurement was performed in oscillations at 10 Hz at 25°C, 37°C and 55°C. The results show different evolutions of the elastic G’ and viscous G’’ modulus as a function of temperature. There is a crossing of G’ and G’’ at 25°C, G’ greater than G’’ at 37°C, and finally G’ and G’’ forming a plateau at 55°C, characteristic of a gel. The knowledge of these rheological behaviour is crucial for the design and operating instructions of anaerobic digestion reactors for residues with high TS content. The Vane geometry would, therefore, be an effective tool for characterizing the rheological behaviour of residues in dry digestion.
MrEtienne Yves-Martial BEUGRE
(University of Strasbourg)
Tantalum phosphide: A topological weyl semimetal.1h
Topological semi-metals are newly discovered states of quantum matter that have arisen interest
in the research community due to their application in spintronics and valleytronics. There are three
types of topological semi-metals (TSMs); Dirac Semi-metal (DSM), Weyl Semi-metal (WSM) and
Node Line Semi-metal (NLSM), each with special features that makes them novel candidates for
future technologies. Unlike topological insulators (TI) that have an energy gap, TSMs have their
valence and conduction bands touching in discrete points in the Brillouin zone. Tantalum phosphide
(TaP), has been classified as a Weyl semi-metal with only a single type of Weyl fermions and thus
topologically distinguished from tantalum arsenide (TaAs) that has two types of Weyl fermions.
Theoretically, if spin-orbit interaction is turned on in the system, we expect an energy gap. To this
date, little has been devoted to this relativistic interaction in TaP. Our goal will be to calculate the
bandstructure in TaP and how the spin-orbit interaction alters the single Weyl fermions. We will em-
ploy first-principles density functional theory (FPDFT) as implemented in the Siesta code. This study
is not only based on fundamental research interests but also of great potential for future applications.
MrKennedy wamalwa khaemba
(Department of physics, Masinde Muliro University of Science and Technology, 52428-00200, Nairobi, Kenya)
TOWARDS ESTABLISHING SCIENTIFICALLY VALID PROOFS FOR MYTHOLOGICAL COSMOLOGY1h
(General) cosmology (GC) - the scientific study of the origin, evolution and eventual consequence of the universe – may be broadly and conveniently classified into two major parts. These are physical cosmology (PC) and mythological cosmology (MC) (otherwise known as religious mythology) (Peebles, 1993; https://en.wikipedia.org/wiki). There is no doubt that worldwide research on cosmology has been almost totally concentrated on PC thus making many to perceive it as synonymous to GC, to the exclusion of MC (e.g. see Hawking and Penrose, 1996; Greene, 2000; Greene, 2005). There is no doubt that significant results on PC have been arrived at by contemporary cosmologists. As fundamental as the results of these great scientists are, the results are incomplete in describing the entire universe. This is due to the fact that substantial phenomena in the universe, which are hitherto called mystical, may only be explained and formally proved via intense research on MC. This aligns with the views of some physicists such as McKee (2004) who canvassed for intense research in MC to explain gaps in the present state of cosmological knowledge.
That is, conventional PC is limited in terms of scope, method of proof etc. PC focuses on the study of the material manifestation of the universe, with consideration given to motion of planetary objects. For instance, the big bang theory postulates the concept of the expansion (i.e. motion) of the universe via explosion about 15 billion years ago from an unimaginably energetic initial event (Rees, 1998; Khoury et. al., 2002; Tolley and Turok, 2002; Nature, 2019). As a result, methods of proof in PC rely on the traditional areas of applied mathematics, which essentially relate to fluid and solid mechanics. Earlier works on PC include Steinhardt and Turok (2002A; 2002B; 2005; 2006) where the authors advanced a radically new (physical) cosmology, called cyclic universe, in which the universe does not have a beginning or end (Also see Khoury et. al., 2004; Strege, 2010). They contended that what is known as creation is just a part of an infinite cycle of titanic collisions between our universe and a parallel world. Rees (1998) advocated that an infinite family of universes (called baby universes) may each have been created by its own big bang such that each universe acquires a distinctive imprint and its own laws of physics. In Hawking and Mlodinow (2010), the authors, among others, argued that both the theory of quantum mechanics and the theory of relativity assist in understanding how universes could have formed out of nothing. Peebles (1980) proposed the theory of cosmic structure formation.
The goal of the present author’s ongoing research on MC as reported in the present paper is two-fold viz: (i) Provide scientifically acceptable proofs of the validity (or otherwise) of phenomena that are considered metaphysical (ii) Provide a unified cosmic theory which effectively integrates PC with MC. In accomplishing the above, a simplistic view in which existing metaphysical phenomena are considered equivalent to what is hitherto classified as science fiction, is adopted. It is well-known that many science fictions have now been scientifically realized. Classical examples of such are aircraft and drones/robots (Oluwade, 2020). Also, many acts performed by people known as magicians, which in the past appeared to the laymen to be beyond the physical have in contemporary times being revealed as mere manipulation and distortion of known physical principles e.g. see Den (2012). Some of these phenomena are sometimes described as ‘African Science’. In addition, with advances in technology, including machine learning and artificial intelligence, many phenomena which could have been considered scientifically impossible are now made possible. For instance, in the movie/video industry, it is possible to watch the (recorded) video – with exact shape, voice etc - of a clinically dead person. Also, it is possible for a person who is physically present at a particular coordinate position to be invisible to another person who is close by. Furthermore, the interesting case of the hypothetical quantum computers which are now practically being realized is relevant (Feynman, 1982; Oluwade, 2002).
The author’s ongoing effort in establishing non-trivial scientifically valid proofs for mythological cosmological phenomena is generally premised on the following principles in physics and (mathematical) philosophy, namely (McKee, 2004; Hospers, 1953; Russell, 1961):
(i) The wave-particle duality: By the author’s model, the wave phenomena represent the spiritual/metaphysical part of the universe while the particle aspect represents the physical part of the universe.
(ii) Action-reaction duality: This means that for every spiritual/metaphysical manifestation, there is a corresponding physical manifestation, and vice versa. Thus, a fundamental knowledge about metaphysical phenomena gives insight into physical phenomena, and vice versa.
(iii) Cause-effect duality: This emphasizes, for instance, that every effect of a physical event has a cause, and by investigating the effect, one tends to have insight into the cause. The author’s conjecture, which he is working on, is that every physical effect has a cause which can be traced to the metaphysical realm.
In particular, the author’s research activities involve the integration of PC and MC towards a new grand cosmic unification theory. The major instrument of mathematics used is modeling, whereby metaphysical phenomena are reduced to mathematical relationships. Formal proofs or otherwise of the validity of these phenomena are then established on a case by case basis. However, unlike PC - whose nature of research revolves round dynamical systems, fluid mechanics, heat and mass transfer vis-à-vis the study of motion of heavenly bodies - MC uses distinct mathematical methods. Such methods are naturally drawn from areas like Abstract Algebra, Real/Complex Analysis and Fuzzy Logic/Set. These are part of the rich repertoire of acceptable standard methods of proofs in mathematics, notable among which are method of deduction, proof by contradiction, use of a counterexample, proof by hypothesis and mathematical induction (Oluwade, 2006). Essentially, full deployment of mathematics as a revealer, harbinger and purveyor of ‘truth and beauty’ (Russell, 1919) is being pursued. The mathematical methods are then supported with scientific and thought experiments.
Previous works of the author relating to MC include Oluwade (2001) where the well-known general communication system of coding and information theory is used to model metaphysics. That is, a metaphysical phenomenon is modeled as a 6-constituent process, namely Source, Transmitter (or Encoder), Channel, Noise, Receiver (or Decoder) and Destination. The paper is a poster presentation at the 2001 Forum and Annual Meeting of The Sigma Xi, The Scientific Research Society, USA. Although the author was originally invited as an international guest speaker (on Science and Engineering Policy and Development in Developing Countries, with emphasis on Nigeria), he used the opportunity to also make a poster presentation on MC. In Oluwade and Longe (2003), the authors established parallels between the conventional computer binary codes and Ifa Divination codes. Ifa Divination is an ancient mythological practice of the traditional Yoruba people of South Western Nigeria which is still popular in contemporary times. The authors showed that, just like the normal computer binary codes, Ifa Divination codes may be conveniently as a discrete structure. Thus, new characteristics of the Ifa Divination codes were deduced. In furtherance to the above, Oluwade (2019) remarked that there is an appearance of similarity pattern in a major device used for practicing African Traditional Religion (Ifa divination), Christianity (specifically, Catholicism) and Islam. This is a bead-like device which is respectively known as divining chain (whose local name is opele), rosary and tesbih. Thus, results earlier arrived at on Ifa Divination may, to some extent, be extended to the analysis of the practice of Christianity and Islam, and indeed other mythologies which use beads as a medium of metaphysical communication. In particular, a theory of similarity pattern in Abstract Algebra (otherwise known as theory of equivalence relations), is an important tool being used by the present author in his research on MC.
In Oluwade (2011), the authors presented a general model of all existing human languages (from the beginning of human existence in the universe) as computer coded character sets, particularly as subsets of Unicode. The model is a framework for designing a new coded character set which is an extension of the Unicode. Oluwade (2020) presents a critical review of a book (McKee, 2004) written by a professional physicist on fundamental science discoveries with predictions for the future. The book is on progress made in modern physics (quantum mechanics, relativity etc) in relation to other areas of science such as neuroscience, nanoscience and computer science (with respect to quantum computers). Among others, the book author argued for a new science of consciousness which will incorporate not only the conventional natural sciences, but also metaphysics, including proof of a ‘Supreme Observer’. The book also relates to discoveries and projections in PC. In a recent paper, Oluwade et. al. (2020) modeled human languages as computer coded character sets. These are sets through which data are processed as sequences of 0’s and 1’s in the computer (Oluwade, 2004). As a preliminary effort in the paper, the authors presented some mathematical proofs which tend to trace or deduce the (primary) language spoken by the first set of humans on earth. This is done via the family of languages which the primary language belongs to.
In conclusion, this presentation highlights the author’s ongoing research in presenting a holistic description of the universe by capturing all known and possible phenomena which are physical and metaphysical. In essence, the research is an effort to blend mythological cosmology (MC) with physical cosmology (PC), since in the view of the author, both are complementary and not supplementary. The modus operandi is the deployment of non-trivial mathematical principles in establishing proofs for MC and justifying a link between the two categories of cosmology. The author is encouraged in his research by noting the fact that as recent as about five decades ago, PC was regarded as a dead end field of study. The field has however recorded monumental success in the present times. Apart from mathematics, physics, computer science and philosophy, other knowledge areas whose results are being deployed in the author’s research include parapsychology, theology, philosophy, paleontology and archaeology (Onabamiro, 1980). Ultimately, it is expected that the veracity of metaphysical phenomena will be less controversial and substantially validated and accepted in mainstream science, in line with the wish of notable scientists like James (1986).
Keywords: Mythological cosmology, Physical cosmology, Scientific proofs, Metaphysics, Mathematical model
1. Den, Vlog (2012), Magic’s Biggest Secrets Finally Revealed, YouTube. https://www.youtube.com/watch?v=JT4YFHB-mvc <last retrieved in November 2020>
2. Feynman, R. P. (1982), ‘Simulating Physics with Computers’, International Journal of Theoretical Physics, 21, p. 467.
3. Greene, Brian (2000), The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory, Vintage Series, Random House Inc.
4. Greene, Brian (2005), The Fabric of the Cosmos: Space, Time and the Texture of Reality, Vintage.
5. Hawking, Stephen and Penrose, Roger (1996), The Nature of Space and Time, Princeton University Press.
6. Hawking, Stephen and Mlodinow, Leonard (2010), The Grand Design, Bantam Books.
7. Hospers, John (1953), An Introduction to Philosophical Analysis (1953), Routledge.
8. James, William (1986), Essays in Psychical Research, Harvard University Press.
9. Khoury, J.; Ovrut, B. A.; Seiberg, N. P.; Steinhardt, J.; and Turok, N. (2002), ‘From Big Crunch to Big Bang’, Physical Review D65, 086007.
10. Khoury, J.; Steinhardt, P. J.; and Turok, N. (2004), ‘Designing Cyclic Universe Models’, Physical Review Letters 92, 2004, 031302
11. McKee, John W. (2004), New Horizons in Science (From the Meaning of Spin to the Nature of Consciousness), Professional Press, Chapel Hill, USA.
12. Nature (editorial) (2019), ‘Big Bang Theory’, Nature Physics 15, 1103. https://www.nature.com/articles/s41567-019-0720-4 <last retrieved in November 2020>
13. Oluwade, Bamidele (2001), ‘A Metaphysical Model of the General Communication System’, poster presentation at the 2001 Annual Meeting and Research Forum of Sigma Xi, The Scientific Research Society, held at the Sheraton Capital Centre, Raleigh, USA.
14. Oluwade, Bamidele (2002), Design, Analysis and Uses of Classical and Quantum Computer Codes, Conversion Project Report, M.Phil/PhD to PhD Degree in Computer Science, University of Ibadan, Ibadan, Nigeria.
15. Oluwade, ‘Dele (Bamidele) and Longe, Olu (2003), ‘On the Code Characteristics of the Ifa Divination Codes’, The Journal of Computer Science and Its Applications (Journal of the Nigeria Computer Society), Vol. 9, No. 1, pp. 23 -28. https://www.academia.edu/37270132/On_the_Code_Characteristics_of_the_Ifa_Divination_Codes <last retrieved in October 2020>.
16. Oluwade, Bamidele (2004), Design and Analysis of Computer-Coded Character Sets, PhD Thesis, University of Ibadan, Nigeria.
17. Oluwade, Bamidele (‘Dele) (2006), ‘There is Truth and Beauty in Undergraduate Mathematics Research’(editorial), American Journal of Undergraduate Research, Vol. 2, No. 4, pp. v-vi. www.ajuronline.org/uploads/Volume 2/Issue 4/24A-OluwadeEditorial.pdf <last retrieved in October 2020>.
18. Oluwade, Bamidele (2011), ‘Design of a Byte-based Coded Character Set’, The Journal of Computer Science and Its Application (An International Journal of the Nigeria Computer Society), Vol. 18, No. 2, pp. 42 – 54. https://researchgate.net/publication/327160707_DESIGN_OF_A_BYTE-BASED_CODED_CHARACTER_SET <last retrieved in October 2020>
19. Oluwade, Bamidele (2019), ‘Management Meets Theology: Reflections on the Contribution of Nigerian University Intellectuals to Management Development via Theology’, African Journal of Management Information System, Vol. 1, Issue 3, pp. 57-75; https://afrjmis.files.wordpress.com/2019/08/vol1issue3jul19paper5journalformatpagenumb.pdf <last retrieved in October 2020>
20. Oluwade, Bamidele; Osofisan, Adenike; Ilori, S. A; Shola, P. B. and Akin-Ojo, R. (2020), ‘A Computational Model for Studying the Characteristics of Languages using Coded Character Sets’, University of Ibadan Journal of Science and Logics in ICT Research (Journal of the Department of Computer Science, University of Ibadan, Nigeria), Vol. 4, No. 1, 85-95. https://journals.ui.edu.ng/index.php/uijslictr/article/view/83/65 <last retrieved in October 2020>
21. Oluwade, Bamidele (2020), ‘Review of a Book on Fundamental Science Discoveries and Predictions as Authored by John W. McKee (1926 – 2009), African Journal of Management Information System, Vol. 3, Issue 2, pp. 1-11. https://afrjmis.wordpress.com/2020/10/jmisvol23paper1pagenumb.pdf <last retrieved in October 2020>
22. Onabamiro, Sanya (1980), Philosophical Essays, Evans Brothers Nig Ltd.
23. Peebles, P. J. E. (1980), The Large-Scale Structure of the Universe, Princeton University Press.
24. Peebles, P. J. E. (1993), Principles of Physical Cosmology, Princeton University Press.
25. Rees, Martin (1998), Before the Beginning: Our Universe and Others, Basic Books.
26. Russell, Bertrand (1919), Mysticism and Logic and other Essays, Longman.
27. Russell, Bertrand (1961), The Basic Writings of Bertrand Russell (1961), George Allen & Unwin Ltd.
28. Steinhardt, P. J. and Turok, N. (2002A), ‘A Cyclic Model of the Universe’, Science, May, 1436.
29. Steinhardt, P. J. and Turok, N. (2002B), ‘Cosmic Evolution in a Cyclic Universe’, Physical Review D65, 126003.
30. Steinhardt, P. J. and Turok, N. (2005), ‘The Cyclic Model Simplified’, New Astronomy Reviews 49, 43
31. Steinhardt, Paul J. and Turok, Neil (2006), Endless Universe: Beyond the Big Bang – Rewriting Cosmic History, Onion Publishing Group Limited.
32. Strege, Charlotte (2010), A Comparison of Two Cosmological Models: Inflationary Cosmology and the Cyclic Universe, Master of Science Thesis, Imperial College, London.
33. Tolley, A. J. and Turok, N. (2002), ‘Quantum Fields in a Big Crunch/Big Bang Spacetime’, Physical Review D66, 2002, 106005
(Principal Consultant/CEO, Dewade Systems Consult, and Department of Mathematical Sciences, Faculty of Natural Sciences, Kogi State University, Nigeria)
XRD, USAXS, SAXS and WAXS Investigations of PZN-4.5PT nanoparticles thin Films1h
The Pb(Zn1/3Nb2/3)O3-4.5PbTiO3 (PZN-4.5PT) single crystals showed very large ferroelectric and piezoelectric properties compared to traditional ferroelectric ceramics (BaTiO3 and PZT) used presently as active material in medical imaging, detection and sonars. However, despite these excellent properties, the greatest difficulty to use PZN-4.5PT single crystals on electronic devices is to achieve them in thin layers form because of their incongruent melting property. To overcome this difficulty, we deposit them as thin layers by dispersing their nanoparticles in a gel containing a matrix that can maintain at least their bulk properties. After this size reduction at nanoscale and the annealing process following the deposition, changes and structural transformations would occur. We fabricate with success thin films by dispersing these nanoparticles in a gel. The materials show some agglomeration at the surface of the silicon substrate films (from SEM images) and non-identified hexagonal microcrystals, which could be at the origin of their excellent properties.
In this paper we use the combined USAXS/SAXS/WAXS instrument at 9ID beamline at APS-ANL for in situ characterization of undoped and 1% Mn doped PZN-4.5PT inorganic perovskite nanoparticles thin films deposited on nanostructured silicon to understand the phases transitions and determine the observed hexagonal microcrystals structure. It revealed a hexagonal structure of the nanoparticles thin films, which could be explained by the new phase that can be assigned to the Pb3(PO4)2 based component. The peak at 31° indicates the presence of the rhombohedral phase perovskites assigned to the nanoparticles. XRD spectra, Raman and EDX mapping are compared to the USAXS, SAXS and WAXS results.
Keywords: Perovskite, nanoparticles, thin film, Synchrotron, Xray
Figure 1: EDX mapping for PZN-4.5PT thin film on silicon substrate after annealing.
(University Assane Seck of Ziguinchor)