Thermal conductivity of crystal lattice of compounds with inhomogeneous variable valence of rare-earth ions

One measured χ thermal conductivity (within 4-300 K range) and σ electric conductivity (within 80-300 K range) of Sm3S4 polycrystalline sample. It is shown that under T > 95 K one observed charge transfer. Within low temperature range the lattice constituent of thermal conductivity - χph ∼ T2.6, within 20-50 K temperature range χph ∼ T-1.2, while under T > 95 K when charge transfer manifests itself χph ∼ T-0.3 and one observes essential residual thermal resistance. One makes conclusion that in compounds with inhomogeneous variable valence of rare-earth ions to which Sm3S4 belongs, when electrons transfer from Sm2+ to Sm3+ and back to Sm2+ one observes local stresses in crystalline lattice resulting in variation of χph temperature dependence from T-1.2 to T-0.3 and manifestation of residual thermal resistance