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SUMMARY:Ab-initio study of structural stability and electronic structure o
f monoclinic and cubic ZrO_{2-x}S_{x}x for 0 ≤ X < 2
DTSTART;VALUE=DATE-TIME:20110713T150000Z
DTEND;VALUE=DATE-TIME:20110713T170000Z
DTSTAMP;VALUE=DATE-TIME:20240617T233023Z
UID:indico-contribution-5268@events.saip.org.za
DESCRIPTION:Speakers: Masilu Godfrey Mulaudzi (University of Limpopo)\nThe
system ZrO2-xSxx is limited by the cases ZrO2 and ZrS2 (x = 0\, 2). Physi
cal properties of such systems for 0 < x < 2 are of great interest\, but d
ifficult to obtain from first principles calculation. A recently suggested
approach\, i.e virtual crystal approximation\, allows simulation for chan
ges in composition\, while retaining a small unit cell. In this paper we e
mploy Density Functional Theory (DFT) within the Generalized Gradient Appr
oximation (GGA)to study the zirconium dioxide – sulfide system ZrO2-xSxx
\, using the CASTEP code. We investigated geometric cell size effects\, me
chanical properties and electronic structure for these systems at various
amounts of sulfur concentrations. For the treatment of solid solutions in
the recently introduced VCA approach\, CASTEP allows to define partial occ
upancies for atomic sites\; in our case\, the anionic lattice sites of ZrO
2-xSxx crystal are defined to be less than fully oxygen occupied: (2-x)\;
and consequently similar sites can then be attributed a partial sulfur cha
racter: (x). The lattice parameters and cell size increases for zirconia a
s the sulfur content is increased. Furthermore\, the trend of Fermi level
and the electron distributions differ\, giving rise to reduced band gap as
S is increased. The cubic structure ZrO2-xSxx is stable for x<1.2\, howev
er\, the structure gives negative tetragonal shear modulus at x≥1.2\, co
ndition of mechanical instability.\n\nhttps://events.saip.org.za/event/7/c
ontributions/5268/
LOCATION: Asteria
URL:https://events.saip.org.za/event/7/contributions/5268/
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