Pan Zhao, Liang Zhengli, Wang Xiao, Fang Yue-Wen, Ye Xubin, Liu Zhehong, Nishikubo Takumi, Sakai Yuki, Shen Xi, Liu Qiumin, Kawaguchi Shogo, Zhan Fei, Fan Longlong, Wang Yong-Yang, Ma Chen-Yan, Jiang Xingxing, Lin Zheshuai, Yu Richeng, Xing Xianran, Azuma Masaki, Long Youwen
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama, 226-8503, Japan.
Mater Horiz. 2024 Oct 28;11(21):5394-5401. doi: 10.1039/d4mh00795f.
The rare physical property of negative thermal expansion (NTE) is intriguing because materials with a large NTE over a wide temperature range can serve as high-performance thermal expansion compensators. However, the applications of NTE are hindered by the fact that most of the available NTE materials show small magnitudes of NTE, and/or NTE occurs only in a narrow temperature range. Herein, for the first time, we investigated the effect of anion substitution instead of general Pb/Ti-site substitutions on the thermal expansion properties of a typical ferroelectric NTE material, PbTiO. Intriguingly, the substitution of S for O in PbTiO further increases the tetragonality of PbTiO. Consequently, an unusually enhanced NTE with an average volumetric coefficient of thermal expansion of = -2.50 × 10 K was achieved over a wide temperature range (300-790 K), which is in contrast to that of pristine PbTiO ( = -1.99 × 10 K, RT-763 K). The intensified NTE is attributed to the enhanced hybridization between Pb/Ti and O/S atoms by the substitution of S, as evidenced by our theoretical investigations. We therefore demonstrate a new technique for introducing mixed anions to achieve a large NTE over a wide temperature range in PbTiO-based ferroelectrics.
负热膨胀（NTE）这种罕见的物理性质很有趣，因为在宽温度范围内具有大NTE的材料可作为高性能热膨胀补偿器。然而，NTE的应用受到阻碍，因为大多数现有的NTE材料显示出小的NTE幅度，和/或NTE仅在窄温度范围内出现。在此，我们首次研究了阴离子取代而非一般的Pb/Ti位取代对典型铁电NTE材料PbTiO热膨胀性能的影响。有趣的是，在PbTiO中用S取代O进一步增加了PbTiO的四方性。因此，在宽温度范围（300 - 790 K）内实现了异常增强的NTE，平均体积热膨胀系数为 = -2.50×10 K，这与原始PbTiO（ = -1.99×10 K，RT - 763 K）形成对比。理论研究表明，增强的NTE归因于通过S取代使Pb/Ti与O/S原子之间的杂化增强。因此，我们展示了一种引入混合阴离子以在基于PbTiO的铁电体中在宽温度范围内实现大NTE的新技术。
