Crystal structures of La3ZrSb5, La3HfSb5, and LaCrSb3. Structural relationships in ternary rare-earth antimonides

The crystal structures of the ternary rare-earth antimonides La3ZrSb5, La3HfSb5, and LaCrSb3 have been determined from single-crystal X-ray data (La3ZrSb5: P6(3)/mcm, Z=2, a=9.5743(9) Angstrom, c=6.3495(7) Angstrom, V=504.1(1) Angstrom(3), T=-60 degrees C. La3HfSb5: P6(3)/mcm, Z=2, a=9.557(2) Angstrom, c=6.3388(6) Angstrom, V=501.4(1)Angstrom(3), T=-60 degrees C. LaCrSb3: Pbcm, Z=4, a=13.2835(7) Angstrom, b=6.2127(2) Angstrom, c=6.116(1) Angstrom, V=504.8(1) Angstrom(3), T=22 degrees C). The structure of La3MSb5 (M=Zr, Hf) consists of chains of Sb atoms and chains of face-sharing MSb6 octahedra, separated by La atoms. LaCrSb3 is isostructural to CeCrSb3, and consists of nearly square sheets of Sb atoms and layers of face- and edge-sharing CrSb6 octahedra, separated by the rare-earth atoms. The RECrSb3 series, previously shown to exist for RE=La, Ce, Pr, Nd, Sm, has now been extended to include RE-Gd, Tb, Dy. Structural relationships between various ternary rare-earth antimonides are drawn.