Up and Downthe Hill-Plot: Hydrides of CeGe–Structureand Magnetism

Abstract

Abstract The hydrogenation behavior of FeB type CeGe was investigated. Hydrogenation (deuteration) produces mixtures of two modifications, similar to hydrides of other FeB type phases LnTt (Ln = La, Ce, Nd; Tt = Si, Ge). P-CeGeD0.75(2) (Pnma, a = 8.1603(5) Å, b = 4.0938(3) Å, c = 6.2911(4) Å) crystallizes in the LaGeH structure type (filled FeB type), whereas C-CeGeD0.95(3) (Cmcm, a = 4.2958(2) Å, b = 11.9970(7) Å, c = 4.0885(3) Å) crystallizes in the ZrNiH structure type (filled CrB). Similar to CeSiHx the mixtures feature exceptionally high ferromagnetic ordering temperatures of 21.6(1) K for CeGeDx and 22.1(2) K for CeGeHx (x ≤ 1), with the effective magnetic moments of 2.44(1) μB (CeGeDx) and 2.38(1) μB (CeGeHx) being close to the free ion value of 2.54 μB of Ce3+. The hydrides (deuterides) were studied by neutron powder diffraction (NPD), thermal analysis and magnetic susceptibility measurements.