No abstract available

No abstract available

No abstract available

[en] Many binary inorganic systems have one congruently subliming phase; many have none. Few systems have two congruently subliming compositions. The cerium-sulfur system is reported to be such a system. The initial interest in the praseodymium-sulfur system was in the thermodynamics of vaporization of PrS(s) and the dissociation energy of PrS(g) in connection with a systematic study of the rare earth monosulfides. However, when it was found that both PrS and Pr₃S₄ are congruently subliming, as described below, some of the earlier unpublished observations on the lanthanum-sulfur system were re-examined and evidence was found that La₃S₄ may be congruently subliming in addition to LaS, which were earlier shown to be congruent. The thermochemical results of vaporization studies by mass effusion and mass spectrometry of the Pr-S system for the compositions 0.75 < S/Pr < 1.36 are presented here, and congruent and incongruent sublimation in rare earth-sulfur systems are discussed. For this latter purpose, schematic pressure-composition phase diagrams are presented demonstrating various possible vaporization modes

[en] Matrices and inverse matrices for the transformation of component concentrations in a ternary system and its subsystems, which are most frequently encountered in practice, have been prepared and tested using a concrete system. The calculation of eutectics of the ternary system Pi₂S₃-Ga₂S₃-Pr₂O₃ with formation of nonmolecular compounds has been made. 5 refs., 1 fig

[en] Many binary inorganic systems have one congruently subliming phase; many have none. Few systems have two congruently subliming compositions. The cerium-sulfur system is reported to be such a system. The initial interest in the praseodymium-sulfur system was in the thermodynamics of vaporization of PrS(s) and the dissociation energy of PrS(g) in connection with a systematic study of the rare earth monosulfides. However, when it was found that both PrS and Pr₃S₄ are congruently subliming, as described below, some of the earlier unpublished observations on the lanthanum-sulfur system were re-examined and evidence was found that La₃S₄ may be congruently subliming in addition to LaS, which were earlier shown to be congruent. The thermochemical results of vaporization studies by mass effusion and mass spectrometry of the Pr-S system for the compositions 0.75 < S/Pr < 1.36 are presented here, and congruent and incongruent sublimation in rare earth-sulfur systems are discussed. For this latter purpose, schematic pressure-composition phase diagrams are presented demonstrating various possible vaporization modes

[en] Using the methods of differential-thermal, X-ray phase and microstructural analyses the Pr-U-S system is studied. Interaction in the system is investigated and preliminary diagram of liquidus surface is built. The liquidus surface of the Pr-U-S system consists of 10 fields. In the system all the phases are crystallized in the form of double compounds with small amount of the third component. Solid solutions with NaCl structure (Pr,U)S and solid solutions with U₃S₅ structure (U₃S₅-Pr₂US₅-72 mol % US₂) are the exceptions. The Pr₂US₅ compound forms limited solid solution with β-US₂ and continuous row of solid solutions with U₃S₅

[en] Phase equilibria in boundary and some internal polythermal cross sections of the ternary system Pr₂S₃-Pr₂O₃-In₂S₃ were studied by the methods of high-temperature thermal, X-ray phase, X-ray microdiffraction analyses. Existence of new compounds Pr₃In₅S₁₂, Pr₄In₅S_13.5, Pr₃InS₆, (PrO)₄In₂O₂S₃, Pr₂O₂S has been revealed. T-diagrams of the studied polythermal cross sections and projection of liquidus surface of the system Pr₂S₃-Pr₂O₃-In₂S₃ have been plotted. 5 refs.; 2 tabs

[en] The results of low temperature (1-20 K) heat capacity measurements on some RM₅ phases, which are good hydrogen absorbers, and on some La₃S₄-La₂S₃ compounds are reported and discussed. Also included are some measurements on the superconducting LaSsub(1.33)-LaSsub(1.40) phases

[en] The mixing method was used in the temperature range 400--2200⁰K to conduct the first systematic study of the enthalpy of sulfides of the praseodymium-sulfur system. Temperature dependences of the enthalpy, heat capacity, entropy, and corrected Gibbs energy of the investigated compounds were obtained and are recommended for practical use. It was established that enthalpy and heat capacity decrease from PrS to PrS₂ due to an increase in the degree of covalence of the sulfides with an increase in the ratio [S]/[Pr]