The effects of ZnGa{sub 2}O{sub 4} formation on structural and optical properties of ZnO:Ga powders

Gallium-doped zinc oxide (ZnO:Ga 1, 2, 3, 4 and 5 at%) samples were prepared in powder form by modifying the Pechini method. The formation of zinc gallate (ZnGa{sub 2}O{sub 4}) with the spinel crystal structure was observed even in ZnO:Ga 1 at% by X-ray diffraction. The presence of ZnGa{sub 2}O{sub 4} in ZnO:Ga samples was also evidenced by luminescence spectroscopy through its blue emission at 430 nm, assigned to charge transfer between Ga{sup 3+} at regular octahedral symmetry and its surrounding O{sup 2-} ions. The amount of ZnGa{sub 2}O{sub 4} increases as the dopant concentration increases, as observed by the quantitative phase analysis by the Rietveld method.