High-Pressure Synthesis, Structure, and Magnetic Properties of Ge-Substituted Filled Skutterudite Compounds; Ln x Co 4 Sb 12?￠???? y Ge y , Ln = La, Ce, Pr, and Nd

摘要

A series of new Ge-substituted skutterudite compounds with the general composition of Ln x Co 4 Sb 12?￠???? y Ge y , where Ln = La, Ce, Pr, and Nd, is prepared by high-pressure and high-temperature reactions at 7 GPa and 800 ???°C. They have a cubic unit cell and the lattice constant for each compound is 8.9504 (3), 8.94481 (6), 8.9458 (3), and 8.9509 (4) ???? for the La, Ce, Pr, and Nd derivatives, respectively. Their chemical compositions, determined by electron prove microanalysis, are La 0.57 Co 4 Sb 10.1 Ge 2.38 , Ce 0.99 Co 4 Sb 9.65 Ge 2.51 , Pr 0.97 Co 4 Sb 9.52 Ge 2.61 , and Nd 0.87 Co 4 Sb 9.94 Ge 2.28 . Their structural parameters are refined by Rietveld analysis. The guest atom size does not affect the unit cell volume. The Co?￠????Sb/Ge distance mainly determines the unit cell size as well as the size of guest atom site. The valence state of lanthanide ions is 3+.