Tan Zhijian, Miao Ping, Hagihala Masato, Lee Sanghyun, Ishikawa Yoshihisa, Torii Shuki, Yonemura Masao, Saito Takashi, Deng Sihao, Chen Jie, He Lunhua, Du Rong, Zhang Junrong, Li Haisheng, Sun Junliang, Wang Yingxia, Lin Xiaohuan, Li Kuo, Kamiyama Takashi
Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tokai, Ibaraki 319-1106, Japan.
Department of Materials Structure Science, Sokendai (The Graduate University for Advanced Studies), Tokai, Ibaraki 319-1106, Japan.
J Phys Chem Lett. 2020 Aug 20;11(16):6785-6790. doi: 10.1021/acs.jpclett.0c01919. Epub 2020 Aug 7.
Zero thermal expansion (ZTE) materials are highly desired in modern industries where high-precision processing is necessary. However, ZTE materials in pure form are extremely rare. The most widely used are Invar alloys, where the ZTE is intimately associated with spontaneous magnetic ordering, known as the magnetovolume effect (MVE). Despite tremendous studies, there is still no consensus on the microscopic origin of MVE in Invar alloys. Here, we report the discovery of room-temperature isotropic ZTE in a pure-form cobaltite perovskite, A-site disordered LaBaCoO. The temperature window of the anomalous thermal expansion shows large tunability by simply altering the oxygen content, making this material a promising candidate for practical applications. Furthermore, we unveil with compelling experimental evidence that the ZTE originates from an isostructural transition between antiferromagnetic large-volume phase and ferromagnetic small-volume phase, which might shed light on the MVE in Invar alloys.
零热膨胀（ZTE）材料在需要高精度加工的现代工业中备受青睐。然而，纯形式的ZTE材料极为罕见。使用最广泛的是因瓦合金，其中ZTE与自发磁有序密切相关，即所谓的磁体积效应（MVE）。尽管进行了大量研究，但对于因瓦合金中MVE的微观起源仍未达成共识。在此，我们报告在一种纯形式的钴酸盐钙钛矿A位无序的LaBaCoO中发现室温各向同性ZTE。通过简单改变氧含量，反常热膨胀的温度窗口显示出很大的可调性，使这种材料成为实际应用的有前途的候选者。此外，我们用令人信服的实验证据揭示，ZTE源于反铁磁大体积相和铁磁小体积相之间的同结构转变，这可能为因瓦合金中的MVE提供线索。
