(Fe1-xNix)ZrF6固溶体晶体结构与可调控的热膨胀性质

绝大部分物质具有热胀冷缩的基本性质，然而近年来的研究发现一些化合物具有反常的负热膨胀性质，其为有效调节物质热膨胀系数(CTE)提供了可行性，尤其调控各向同性化合物热膨胀性质是一个重要的研究方向。本文以双ReO₃结构的固溶体(Fe_1-xNi_x)ZrF₆为研究对象，对(Fe_1-xNi_x)ZrF₆固溶体的制备、晶体结构以及热膨胀调控开展了深入研究。(Fe_1-xNi_x)ZrF₆固溶体呈现全程固溶特性，通过Ni²⁺对Fe²⁺进行化学替代的方法实现了(Fe_1-xNi_x)ZrF₆热膨胀系数在大范围内的有效调控(?3.24×10^?6– +18.23 × 10^?6 K^?1，300–675 K)，尤其，在(Fe_0.5Ni_0.5)ZrF₆化合物中得到了零膨胀性能。作为一种典型的框架结构化合物，晶胞中F原子横向热振动的差异是导致各自不同热膨胀差异的本质原因。该研究给我们提供了一个基于开放式框架结构化合物的热膨胀调控方法。

Controllable Thermal Expansion and Crystal Structure of (Fe1-xNix)ZrF6 Solid Solutions

Most materials expand on heating and contract on cooling. In the recent years, however, some compounds have been found to exhibit abnormal negative thermal expansion (NTE) behavior; this presents an opportunity to adjust the coefficient of thermal expansion (CTE) of such materials. It is especially important to obtain controllable thermal expansion in isotropic compounds. Herein, we report the preparation, crystal structure, and controllable thermal expansion in double ReO₃-type (Fe_1-xNi_x)ZrF₆ solid solutions. (Fe_1-xNi_x)ZrF₆ exhibits full range solubility. A controllable thermal expansion of (Fe_1-xNi_x)ZrF₆ could be achieved by the chemical substitution of Ni²⁺ for Fe²⁺ over a wide range of CTE from ?3.24 × 10^?6 to +18.23 × 10^?6 K^?1 (300–675 K). In particular, zero thermal expansion was obtained for the composition (Fe_0.5Ni_0.5)ZrF₆. As a kind of typical framework structure, the transverse thermal vibrations of fluorine atoms are expected to play a critical role in the thermal expansion behavior of double-ReO₃ compounds. This study presents a potential method to tune the thermal expansion of NTE (negative thermal expansion) families which have an open framework structure.