Luminescence study of nanosized Al₂O₃:Tb³⁺ obtained by gas-dispersed synthesis

Terbium-doped Al₂O₃ samples were obtained by gas-dispersed synthesis. It was shown that the resulting powders, with particle sizes of 10-70 nm, consist of a mixture of transition aluminas, among which the δ ^*-polymorph is dominant. The luminescence properties of Al₂O₃:Tb³⁺ have been studied upon excitation in the UV-visible range of the spectrum. It was found that Tb³⁺ ions cause several groups of inhomogeneously broadened emission bands in the range of 470-640 nm, which are characteristic for disordered materials. In addition, the emission spectra contain a broad band at about 450 nm and several narrower ones in the 680-720 nm region. These features are attributed to surface defects and impurity Cr³⁺ ions occupying Al³⁺ octahedral positions, respectively.