Phonon Spectrum and Elastic Properties of Y2Sn2O7

The phonon spectrum of yttrium stannate Y₂Sn₂O₇ is calculated within a general ab initio approach and the frequencies and types of IR and Raman modes are determined. The degree of involvement of ions in phonon modes is determined from the analysis of displacement vectors calculated ab initio. The elastic constants and hardness of Y₂Sn₂O₇ are calculated. The impurity ion–ligand distance in Y₂Sn₂O₇:Yb³⁺, Y₂Sn₂O₇:Eu³⁺, Lu₂Sn₂O₇:Yb³⁺, Nd₂Sn₂O₇:Gd³⁺, and Nd₂Sn₂O₇:Tb³⁺ impurity centers is calculated.