Isotropic Low Thermal Expansion over a Wide Temperature Range in Ti_1–xZr_xF_3+x (0.1 ≤ x ≤ 0.5) Solid Solutions

Journal Article · 30 October 2018 · Inorganic Chemistry

DOI: https://doi.org/10.1021/acs.inorgchem.8b02593 · OSTI ID:1487256

Yang, Cheng  ^[1]; Zhang, Yugang ^[2]; Bai, Jianming ^[2]; Tong, Peng ^[1]; Lin, Jianchao ^[3]; Tong, Haiyun ^[1]; Zhang, Lei ^[3]; Wen, Wen  ^[4]; Zhang, Xingmin ^[4]; Sun, Yuping ^[5]

---

1. Chinese Academy of Sciences, Hefei (People's Republic of China); Univ. of Science and Technology of China, Hefei (People's Republic of China)
2. Brookhaven National Lab. (BNL), Upton, NY (United States)
3. Chinese Academy of Sciences, Hefei (People's Republic of China)
4. Chinese Academy of Sciences, Shanghai (China)
5. Chinese Academy of Sciences, Hefei (People's Republic of China); Chinese Academy of Sciences, Hefei (People's Republic of China)

TiF₃ exhibits a rhombohedral to ReO₃-type cubic phase transformation at ~340 K. Here we report that, by introducing ZrF₄ into TiF₃, the cubic phase is stabilized at least down to 123 K in the Ti_1–xZr_xF_3+x compounds. All compounds exhibit low thermal expansion (LTE) between 123 and 623 K, and a nearly zero thermal expansion (ZTE) was obtained in Ti_0.7Zr_0.3F_3.3 (α_L = 0.91 ppm/K). The analysis of pair distribution function reveals that the cation-centered octahedra are partially changed to pentagonal bipyramids in Ti_1–xZr_xF_3+x due 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. Lastly, our present strategy is applicable to other rhombohedral metal trifluorides for the design of new isotropic ZTE materials.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: SC0012704
• OSTI ID: 1487256
• Report Number(s): BNL-209761-2018-JAAM
• Journal Information: Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 22 Vol. 57; ISSN 0020-1669
• Publisher: American Chemical Society (ACS)Copyright Statement
• Country of Publication: United States
• Language: English