Temperature dependences of the elastic moduli, absorption of ultrasound, and the thermal expansion of sm1-x GdxS single crystals

The young modulus E 100 (T), the shear modulus G 100 (T), the lattice constant a(T), and the thermal expansion Δl/l were deterpined in the temperature range 300-1200 K for SmS, Sm 0.86 Gd 0.14 S, and Sm 0.82 S. The Young modulus of one of the samples with 14% Gd was determined in a wide range 6-1200 K, and the absorption of ultrasound was measured at a freqency of about 100 kHz at 6-300 K. The Sm 1-x Gd x S solid solutions had minima in the temperature dependences of the Yound modulus. A comparison of these minima with the T-x phase diagram demonstrated that the anomaly exhibited by the «gold-phase» sample (18% Gd) corresponded to the familiar transcritical phase transition, whereas the anomaly exhibited by the «black» sample (14% Gd) was due to a new transition