The thermodynamic characteristics of lanthanum, praseodymium, neodymium, and gadolinium mono-bismuthides

Abstract

Investigation of the high-temperature behavior in vacuum by the Knudsen effusion method in combination with mass spectrometric, chemical, and x-ray diffraction analyses makes it possible to establish the composition of the vapor, the type of evaporation reaction, and the presence and extent of the area of homogeneity, to determine the partial pressure of the components of the vapor, and to calculate the enthalpy of the reaction and other thermodynamic characteristics related to it. In this work powders of monobismuthides of lanthanum, praseodymium, neodymium, and gadolinium obtained by ampul synthesis from the elements were used. According to the data of chemical analysis the original specimens contained (wt.%): LaBi-39.85 La, 60.05 Bi; PrBi - 40.25 Pr, 59.70 Bi; NdBi - 40.80 Nd, 59.15 Bi; GdBi - 42.93 Gd, 57.04 Bi. X-ray diffraction analysis showed that the test specimens have a NaCl-type cubic lattice with parameters of the elementary cell of a = 0.6577, 0.6460, 0.6424, and 0.6315 nm for LaBi, PrBi, NdBi, and GdBi, respectively.