Physical properties and phase transitions of the rare earth monosulphides in the homogeneity range

Abstract

The heat capacity (C), lattice constant (a), density (d), and electrical conductivity (σ) of RE monosulphides LnSx (Ln = La, Pr, Nd, and Gd) are studied in the homogeneity range (up to x = 0.80). A vacuum adiabatic calorimeter is used to measure C between 2 and 300 K. A systematic analysis of the experimental densities and those calculated from X‐ray data reveals the vacancies in the sulphur sublattice for x < 1. The Schottky heat capacity, the crystal field parameters, and the energy levels of the Pr3+ and Nd3+ ions are found to be nearly the same for any x. Four sharp peaks for NdS at 8.4, 9.3, 9.7, and 11.5 K and three anomalies for GdS at 5.4, 27, and 60 K are observed. The smoothed experimental C data are tabulated. The standard entropy and enthalpy values are calculated.

Magnetic and thermophysical properties of GdXMn1−XS solid solutions

“…In the region of the critical concentration of the break of the long-range magnetic order, the Néel temperature sharply drops. Using the phase diagram of the disordered binary alloy A x B 1−x for an antiferromagnet with fcc lattice having the second type of ordering [19], one can estimate the value of the exchange interactions between the nearest neighbors J MnCd /J MnMn ∼ 4 and the next-nearest neighbors K MnCd /J MnMn ∼ 1.…”