Discrete zero-phonon Cr3+ lines in the spectra of Terbium–Yttrium–Lutetium Aluminum garnets solid solutions: Lattice compression and dilation

Abstract

Abstract The zero-phonon electronic transitions in Cr 3+ impurity ions in a series of Tb 3 z Y 3 −3 z Al 5 O 12 (0 z 3 x Y 3 −3 x Al 5 O 12 (0 x 2 E– 4 A 2 ) fluorescence spectra of Cr 3+ ions were observed which are not accompanied by strong inhomogeneous broadening, as usually happens in solid solutions. This effect which was first observed in LuYAG and ascribed to high C 3i symmetry of Cr 3+ (Al 3+ ) sites that allows only a limited number of non-equivalent Cr 3+ centers in mixed environment. The energies and radiative lifetimes of 2 E states of locally identical Cr 3+ centers inside different Tb–Y–Lu mixed garnet matrices are studied; the observed dependences on Tb and Lu content are discussed in terms of lattice compression and dilation according to Vegard׳s law. Selective laser spectroscopy confirms the small number of non-equivalent Cr 3+ centers in garnet solid solutions.