Phase equilibria chalcogenides

A. A. Eliseev and G.M. Kuzmichyeva, Phase equilibrium and crystal chemistry in ternary rare earth systems with chalcogenide elements 191... 

Because intermetallic systems undoubtedly display certain special features that follow from their metallic binding forces, considerable importance attached to the growing evidence that the chalcogenides, the essentially ionic oxides, the nitrides, and other representative binary compounds of the transition metals were, not infrequently, both variable and irrational in composition. Schenck and Ding-mann s equilibrium study of the iron-oxygen system (39) was notable in this connection They showed that stoichiometric ferrous oxide, FeOi 000, the oxide of an important and typical valence state, did not exist. It lay outside the broad existence field of a nonstoichiometric phase. It is, perhaps, still not certain... 

Density functional theory has been used to calculate the P-E bond energies and orbital populations of trimethylphosphine chalcogenides and related compounds. The results indicate that Me3P=CH2 has a 7i-bond order of 0.5. The equilibrium acidities in DMSO solution and gas-phase homolytic bond dissociation energies of tributylphosphonium ylide precursors have also been determined. ... 

Other Metal Sulphides. The equilibrium between stoicheiometric TaSj and a non-stoicheiometric phase Ta g4 has been established by measurement of the electrical properties of compositional isotherms with the vapour pressure of sulphur between 900 and 1200 °C. The rules governing the formation of stable structures in the series of compounds (ZnO, and chalcogenides... 

TABLE 4 Calculated transition pressures for the electronic and structural phase transitions in the Ce pnictides and chalcogenides. Also quoted are the volume discontinuities (relatively to the zero pressure equilibrium volume) at the transition. The notation (f") refers to SIC-LSD calculations with n localized f-electrons. For the cerium pnictides, B2 denotes the distorted B2 structure. Experimentally, the transitions of the Ce pnictides are discontinuous, while those of the cerium chalcogenides (at room temperature) are continuous... 

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