Isotropic Low Thermal Expansion over a Wide Temperature Range in Ti1- xZr xF3 x (0.1
Isotropic Low Thermal Expansion over a Wide Temperature Range in Ti1- xZr xF3 x (0.1
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Ti1- xZr xF3 x (0.1) 在宽温度范围内具有各向同性的低热膨胀
DOI：
10.1021/acs.inorgchem.8b02593
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Sun Yuping
中科院分区：
文献类型：
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作者：
Yang Cheng;Zhang Yugang;Bai Jianming;Tong Peng;Lin Jianchao;Tong Haiyun;Zhang Lei;Wen Wen;Zhang Xingmin;Sun Yuping
TiF_3在340 K时发生菱面体向ReO_3型立方相转变。本文报道了在TiF 3中引入ZrF 4，使Ti 1-xZrxF 3 + x化合物的立方相至少在123 K下保持稳定。所有化合物在123 ~ 623 K范围内均表现出低的热膨胀（LTE），其中Ti 0.7Zr 0.3F 3.3的热膨胀（ZTE）几乎为零（αL= 0.91 ppm/K）。对分布函数的分析表明，由于相对于TiF_3，F的过量引入，Ti_（1-x）Zr_xF_（3 + x）中的阳离子中心八面体部分转变为五角双锥。因此，多面体的协同旋转倾向于受到限制，并且立方相因此稳定。受约束的多面体旋转与引入Zr 4+引起的晶格软化竞争，从而产生LTE。我们的策略也适用于其他菱面体金属三氟化合物，以设计新的各向同性ZTE材料。
TiF3exhibits a rhombohedral to ReO3-type cubic phase transformation at ∼340 K. Here we report that, by introducing ZrF4into TiF3, the cubic phase is stabilized at least down to 123 K in the Ti1–xZrxF3+xcompounds. All compounds exhibit low thermal expansion (LTE) between 123 and 623 K, and a nearly zero thermal expansion (ZTE) was obtained in Ti0.7Zr0.3F3.3(αL= 0.91 ppm/K). The analysis of pair distribution function reveals that the cation-centered octahedra are partially changed to pentagonal bipyramids in Ti1–xZrxF3+xdue to the excess fluorines relative to the case of TiF3. Therefore, the cooperative rotation of the polyhedra tends to be restricted, and the cubic phase is thus stabilized. The restrained polyhedral rotations compete against the lattice softening caused by the introduction of Zr4+, giving rise to the LTE. Our present strategy is applicable to other rhombohedral metal trifluorides for the design of new isotropic ZTE materials.