Naslov
Evolution of structural and optical properties in the course of thermal evolution of sol–gel derived cobalt-doped gahnite

Autori
Kurajica, Stanislav ; Tkalčec, Emilija ; Gržeta, Biserka ; Iveković, Damir ; Mandić, Vilko ; Popović, Jasminka ; Kranželić, Dajana

Izvornik
Journal of alloys and compounds (0925-8388) 509 (2011), 7; 3223-3228

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
transition metals compounds ; sol–gel process ; optical properties ; light absorption and reflection

Sažetak
Thermal evolution of sol–gel derived gahnite (ZnAl2O4) with 4, 8 and 12 at.% of Zn replaced with Co was studied by thermal analysis techniques (DTA/TGA), X-ray diffraction (XRD) and V–vis diffuse reflectance spectroscopy (DRS). Zinc–cobalt spinel powders were produced by gel heat treatment at temperatures as low as 400 ◦C. Crystal structure was characterized using Rietveld refinement of X-ray diffraction patterns for the samples annealed at 800 ◦C, simultaneously with the analysis of diffraction line broadening. It was found out that the distribution of Co2+ ions in tetrahedral and octahedral sites of zinc cobalt aluminate crystal lattice, crystallite size and lattice strain depend on Co loading. The green color of samples thermally treated at T < 800 ◦C has been explained as a consequence of partial oxidation of Co2+ ions at lower temperatures and accommodation of Co3+ ions in octahedral sites. Thermal treatment at higher temperatures promote gradual change of color from green to blue, characteristic for tetrahedrally coordinated Co2+ ions. The spectra evolution could be interpreted as a progressive reduction of Co3+ to Co2+ ions at higher temperatures.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo

POVEZANOST RADA