Chykhrij S. The interaction of phosphorus with rare earth and transition metals

The isothermal sections of the phase diagrams of 15 ternary systems RE-M-P have been constructed and 70 new ternary phosphides have been obtained. The crystal structures of 65 compounds have been determined and 15 new structure types have been solved and discussed. The systematisation of the crystal structures of the ternary phosphides has been made and the correlation between phosphorus content in the compound and coordination of its atoms in the structure has been showed. The crystal structures of the compounds belonging to the (R,M)~2X homologous series have been described as built from structural units of the Rm(m-1)/2M(m+1)(m+2)/2Xm(m+1)/2 composition (m is an integer), which are located in the limits of triangular-mesh net (36) of the X-atoms. The correlation between compositions, crystal structures and unit cell parameters for compounds of the (R,M)~2X series has been established. Separate homologous subseries of those structures have been distinguished and some chemical formulas to describe thecompositions of real and hypothetical compounds of the R-M-X systems have been proposed. More considerable part of the covalent chemical bond between the transition metal and phosphorus atoms compared to the Ln-P bonds in ternary phosphides have been showed. It has been showed, that the valency of the rare earth atoms with variable valency have a tendency to decrease when the phosphorus content in the ternary phosphides increases.