Luminescence centers in yttrium silicate and germanate

Luminescence spectra for isostructural Y₂SiO₅ and Y₂GeO₅ are investigated. The spectra are resolved into elementary components by the Alentsev—Fock method. Bands with maxima in regions of 2.6, 2.3, and 2.05 eV in the spectra of Y₂SiO₅ luminescence and in regions of 2.55, 2.25, and 2.0 eV in the spectra of Y₂GeO₅ luminescence are considered as radiative recombination of excited associative donor-acceptor Y³⁺−O²⁻ pairs. The indicated bands are related to certain distances between yttrium (the donor) and oxygen (the acceptor). A band with a maximum of 2.95 eV in Y₂SiO₅ and 3.0 eV in Y₂GeO₅ occurs in recombination of electrons with holes trapped by an anionic sublattice. I. Franko L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 4, pp. 528–531, July–August, 1998.