The linear thermal expansion coefficients in the intermediate valence system Ce₂Ni₃Si₅ were determined along the main crystallographic directions by means of neutron diffraction in the temperature range 10–300 K. The anomalous contribution to thermal expansion due to valence instabilities of cerium was estimated by employing the virtual mix approach. The magnitude of the anomalous magnetic contribution to the volume coefficient of thermal expansion in this intermetallic system is about 1.2× 10⁻⁵ K⁻¹. The observed effect is caused by a strong temperature dependence of the degree of the partial delocalization of the cerium 4f electrons in the intermediate valence regime. The effective Kondo temperature of Ce₂Ni₃Si₅ T_K = 140 К obtained in the present work is in a very good agreement with the earlier estimates based on the temperature dependences of the macroscopic magnetic and thermodynamic properties.

通过中子衍射在10–300 K的温度范围内沿主晶体学方向确定了中间价体系Ce ₂ Ni ₃ Si ₅的线性热膨胀系数。铈的价态不稳定性对热膨胀的异常贡献为通过采用虚拟混合方法进行估算。在该金属间体系中，异常磁性对热膨胀的体积系数的贡献的大小为约1.2×10 ^-5  K ^-1。观察到的效果是由于在中间价态中铈4f电子部分离域化程度的强烈温度依赖性引起的。Ce的有效近藤温度 在当前工作中获得的₂ Ni ₃ Si ₅ T _K = 140К与基于宏观磁和热力学性质的温度依赖性的早期估计非常吻合。