Effect of cobalt doping on zinc aluminate structure (CROSBI ID 532030)
Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | međunarodna recenzija
Podaci o odgovornosti
Popović, Jasminka ; Gržeta, Biserka ; Tkalčec, Emilija ; Kurajica, Stanislav
engleski
Effect of cobalt doping on zinc aluminate structure
Zinc aluminate, ZnAl_2O_4 (mineral name gahnite), is a well known wide-band-gap semiconductor transparent for light wavelengths greater that 320 nm. When doped with Co^(2+), Mn^(3+) or rare-earth ions it exhibits luminescence and can be used as a cathodoluminescent material in multicolor displays. ZnAl_2O_4 possesses a spinel structure, in the space group Fd3m. Its unit cell contains 32 oxygen atoms in cubic close packing, 16 octahedral sites occupied by Al cations and 8 tetrahedral sites occupied by Zn cations. Under specific temperature conditions it can adopt an inverse spinel structure in which Al and Zn share both available cation sites. Powder samples of pure gahnite and ones doped with 4, 8 and 12 at% of Co (substituting for Zn) were prepared by a sol-gel technique. Samples were additionally annealed at 800oC for 2 hours. The cobalt/zinc atomic ratios in the samples were determined by means of PIXE (Particle Induced X-ray Emission) spectroscopy. Prepared samples were characterized by X-ray diffraction at RT using a Philips MPD 1880 counter diffractometer. Diffraction patterns indicated that all prepared samples had the spinel-type structure, no additional phases were detected. Unit-cell parameter a for the undoped and Co-doped gahnite samples was determined using silicon powder as an internal standard, and refined by the whole-powder-pattern fitting method. It decreased with increase of cobalt content in the samples. This behavior can be explained by considering ionic radii of zinc and cobalt. The ionic radius for the 4-coordinated Zn^(2+) (0.074 nm) is higher than that of Co^(2+) (0.071 nm) favoring a decrease in unit cell volume and therefore the lattice contraction when cobalt substitutes zinc. For higher level of cobalt doping, the inverse spinel structure could be expected similar to that of CoAl_2O_4 as reported by Fischer.
Zinc aluminate; Spinel structure; Cobalt doping; X-ray powder diffraction
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Podaci o prilogu
39-39-x.
2007.
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objavljeno
Podaci o matičnoj publikaciji
Sixteen Croatian-Slovenian Crystallographic Meeting. Book of Abstracts
Cetina, Mario ; Popović, Stanko ; Skoko, Željko ; Šantić, Ana ; Štefanić, Zoran
Zagreb: Hrvatska akademija znanosti i umjetnosti (HAZU) ; Hrvatska Kristalografska Zajednica
Podaci o skupu
Sixteen Croatian-Slovenian Crystallographic Meeting
predavanje
13.06.2007-17.06.2007
Petrčane, Hrvatska