Kozak R. Synthesis and crystal structure of phases in the R-Ag-Al-Ge systems (R - rare-earth element of the cerium subgroup)

On the basis of X-ray diffraction, local spectral and structural analyses the isothermal (873 K) sections (33.3 at.% R) of the phase diagrams of the quaternary systems {Pr,Sm}-Ag-Al-Ge have been constructed. In these and related systems with Ce and Nd, the existence of solid solutions based on ternary compounds of the system R-{Ag,Al}-Ge was established. A new quaternary compound SmAg0.55-0.36Al0.43-0.80Ge1.02-0.84 has been synthesized. The crystal structure of the new type PrAgAlGe3 was determined. It was found that each structure type forms within a certain range of valence electron concentration per atom of the mixture Ag + Al + Ge. Magnetic measurements for the AlB2-type solid solutions show that they are well described by the Curie-Weiss law (80-400 K). At low temperatures ferromagnetic ordering is observed.