Abstract

Thermal deformations of noncentrosymmetric silver and bismuth pentaborate AgBi₂B₅O₁₁ are studied by the X-ray diffraction analysis of single crystals. Thermal expansion is anisotropic (α_a = 18, α_b = 5, α_c = 1 × 10⁻⁶°C⁻¹), which is caused by the orientation of the pentaborate B₅O₁₀ groups, along the axis of which the expansion is minimal. With increasing temperature, the degree of noncentrosymmetric deviation of the structure decreases. The parameters of thermal displacements of bismuth are refined in the anharmonic approximation. An assumption is made about the relationship between the shape of the figure of thermal displacements with participation in vibrations perpendicular to the three strongest Bi–O bonds.

中文翻译：

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AgBi 2 B 5 O 11在100至400 K范围内的结构变化

摘要

通过单晶的X射线衍射分析研究了非中心对称的银和五硼酸铋铋AgBi ₂ B ₅ O _11的热变形。热膨胀是各向异性（α_一个= 18，α _b = 5，α _{c ^} = 1×10 ^-6 ℃，^-1），它是由五硼酸盐B的取向造成₅ Ô ₁₀组，沿其最小扩展的轴。随着温度升高，结构的非中心对称偏差程度减小。铋的热位移参数在非谐波近似中得到了改进。假设热位移图形的形状与参与垂直于三个最强Bi-O键的振动的关系。