Abstract Many Laves phases take up considerable amounts of hydrogen to form metallic Laves phase hydrides. They frequently undergo phase transitions driven by ordering phenomena for the hydrogen atom distribution. The cubic Laves phase ZrCr2 takes up hydrogen to form a hydride with almost four hydrogen atoms per formula unit, which undergoes a phase transition to a monoclinic modification at a critical temperature T c = 250.2 K. Its crystal structure was refined based on neutron powder diffraction data on the deuteride (ZrCr2D3.8 type [T = 1.6 K, C2/c]) at four temperatures in the range 50 K ≤ T ≤ 200 K. The monoclinic low-temperature modification features a strongly distorted square anti-prism ZrD8 and three CrD4 polyhedra with almost fully occupied deuterium sites in saddle-like, distorted tetrahedral and planar configurations. Zr–D distances are in the range 201.4(7) pm ≤ d(Zr–D) ≤ 208.5(8) pm and Cr–D distances in the range 172.9(7) pm ≤ d(Cr–D) ≤ 182.4(8) pm.

中文翻译：

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ZrCr2D≈4 在 50 K ≤ T ≤ 200 K 时的晶体结构

摘要 许多 Laves 相吸收了大量的氢以形成金属 Laves 相氢化物。它们经常经历由氢原子分布的有序现象驱动的相变。立方 Laves 相 ZrCr2 吸收氢形成每个分子式单元几乎有四个氢原子的氢化物，在临界温度 T c = 250.2 K 时发生相转变为单斜晶变体。其晶体结构基于中子粉末衍射进行细化氘化物（ZrCr2D3.8 型 [T = 1.6 K，C2/c]）在 50 K ≤ T ≤ 200 K 范围内的四个温度下的数据。单斜低温改性具有强烈扭曲的方形反棱镜 ZrD8 和三个 CrD4 多面体，在鞍状、扭曲的四面体和平面配置中几乎完全占据了氘位点。