Abstract Evolution of crystal structure of PbMoO4 (Wulfenite, tetragonal, I41/a) from 5 to 300 K by in situ low temperature powder neutron diffraction studies is reported. The study revealed no structural transition in the complete range of temperature. The unit cell parameters show anisotropic expansion with about 2.2 times higher expansion along c-axis compared to that along a-axis. From the refined structural parameters, it is emphasized that the expansion of Pb-O bonds in PbO8 (bisdisphenoid) units and their orientations along a- and c-axes are the controlling factors. The MoO4 tetrahedra behaves like a rigid unit in the temperature range of this study. The expansion of unit cell volume is fully arising from the expansion of PbO8 bisdisphenoids. The analyses of anisotropic displacement parameters also show almost smooth variation with temperature down to 5 K. The evolutions of structural parameters of PbMoO4 with temperature suggest it for a promising material for cryogenic applications.

中文翻译：

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PbMoO4 晶体结构在 5 到 300 K 之间的演变：低温粉末中子衍射研究

摘要 报道了通过原位低温粉末中子衍射研究从 5 到 300 K 的 PbMoO4（钨铁矿，四方晶系，I41/a）晶体结构的演变。研究表明在整个温度范围内没有结构转变。晶胞参数显示各向异性膨胀，与沿 a 轴的膨胀相比，沿 c 轴的膨胀高约 2.2 倍。从细化的结构参数中，强调 PbO8（双二酚）单元中 Pb-O 键的扩展及其沿 a 轴和 c 轴的取向是控制因素。MoO4 四面体在本研究的温度范围内表现得像一个刚性单元。晶胞体积的膨胀完全是由 PbO8 双二酚的膨胀引起的。