Acoustic, elastic, and anharmonic properties of Sm _1-xR _xS solid solutions with trivalent impurities (R = Y, La{cyrillic}, Tm)

Based on the known experimental data on the rigidity constants c _ij(x) of single crystals of samarium monosulfide solid solutions (alloys) with yttrium, lanthanum, and thulium impurities, their anisotropic and isotropic acoustic (sound velocities), elastic (elasticity moduli and Poisson's ratios), and anharmonic (Grüneisen parameters) properties are investigated. Anomalous behavior of these characteristics at isostructural electron phase transitions in the examined mixed systems in the intermediate valence state is discussed.