8-12 July 2013
Effects of Cr3+ ions concentration in Cr-doped ZnAl2O4 nanocrystals synthesized using sol-gel process
Presented by Mr. Setumo Victor MOTLOUNG on 9 Jul 2013 from 17:40 to 18:40
Type: Poster Presentation
Track: Track A - Division for Condensed Matter Physics and Materials
A report on the sol-gel preparation of nanosized ZnAl2O4:Cr3+ at a relatively low temperature (~80 °C). The mol% of Cr3+ was varied in the precursor during the synthesis. The gel, dried and annealed powder samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared analysis (FTIR) and photoluminescence (PL) spectroscopy. The XRD data revealed that the dried and annealed samples consist of the mixture of ZnO, Al3O2 and cubic phases of ZnAl2O4. The estimated crystalline size for the cubic spine phase was found to be 28 nm in diameter. The surface morphology of the phosphors was influenced by the mol% of the Cr3+ in the precursor. FTIR spectra showed that the number of bands decreases when the samples are heat-treated at higher temperatures. PL spectra indicated that both undoped and Cr-doped ZnAl2O4 powders exhibit green PL emission when the powders are sintered at 700 oC in air. It indicates that the green emissions come from either the host or Cr3+ ions. However, it is noted that the green emission peaks were at different positions, 515 nm and 530 nm, for undoped and Cr-doped phosphors, respectively.
F.B. Dejene (University of the Free State)