Determination of the local compressibilities for Cr3+ ions in some garnet crystals from high-pressure spectroscopy

Abstract

By using the bond length dependence of the covalency reduction factor obtained from the pressure-induced spectral shifts of ruby (Al2O3:Cr3+), the local compressibilities of Cr3+-O2- bonds for Cr3+ in the octahedral a sites of Y3Al5O12 and La3Lu2Ga3O12 crystals have been determined from their high-pressure spectroscopies. The results are obviously different from the compressibilities of the host crystals. The reasons for the difference are discussed.