Electronic Structure of $Y_{3}Al_{5}O_{12}:V$ Single Crystals, Comparison with Sintered Ceramics

$Y_{3}Al_{5}O_{12}$ (YAG) single crystals doped with vanadium ions $(V^{3+})$ were obtained by the Czochralski method. The X-ray photoelectron spectra of YAG:V annealed in reducing atmospheres: $H_{2}$, vacuum and $H_{2}$ + vacuum are presented and compared with the spectra of the YAG ceramics. The X-ray photoelectron spectra showed that the vanadium dopant concentration in YAG:V crystals is lower than a nominal one. For the "as grown" YAG:2.8at.%V crystal vanadium exists in the mixed valence state. The increase in lattice parameters for the samples annealed in hydrogen was found.