Negative thermal expansion and the role of hybridization in perovskite-type PbTiO3-Bi(Cu0.5Ti0.5)O-3
Negative thermal expansion and the role of hybridization in perovskite-type PbTiO3-Bi(Cu0.5Ti0.5)O-3
复制标题
钙钛矿型 PbTiO3-Bi(Cu0.5Ti0.5)O-3 的负热膨胀和杂化作用
DOI：
10.1039/c9qi01546a
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发表时间：
2020
影响因子：
7
通讯作者：
Xing Xianran
中科院分区：
文献类型：
--
作者：
Fan Longlong;Li Qiang;Zhang Linxing;Shi Naike;Liu Hui;Ren Yang;Chen Jun;Xing Xianran
PbTiO_3-BiMeO_3铁电材料不仅具有极大的极化和压电性，而且具有可控的热膨胀，因此受到人们的广泛关注。在这项研究中，我们提出了一个新的二元系统（1-x）PbTiO 3-xBi（Cu0.5Ti0.5）O3具有大的四方性和增强的自发极化。有趣的是，在室温至TC（约550 °C）的温度范围内，在四钛酸铅0.85PbTiO3-0.15Bi（Cu0.5Ti0.5）O3中观察到了接近零的热膨胀和负热膨胀的组合。综合结构分析指出，反常热膨胀与自发体积铁电致伸缩耦合。最大熵法研究表明，Pb/Bi-O键的共价杂化对铁电性的提高起着至关重要的作用，并与热振动相互作用，控制了从正向负的热膨胀转变.本文的研究为验证理论计算提供了直接证据，并可推广到揭示铁电体热膨胀的本质。
PbTiO3-BiMeO3 ferroelectrics have attracted much attention due to not only their extremely large polarization and piezoelectricity but also their controllable thermal expansion. In this study, we present a new binary system of (1 − x)PbTiO3-xBi(Cu0.5Ti0.5)O3 possessing large tetragonality and enhanced spontaneous polarization. Interestingly, a combination of near zero thermal expansion and negative thermal expansion over a temperature range of RT to TC (∼550 °C) has been observed in tetragonal 0.85PbTiO3-0.15Bi(Cu0.5Ti0.5)O3. The comprehensive structure analysis addressed that the abnormal thermal expansion is coupled to the spontaneous volume ferroelectrostriction. Moreover, the chemical bonding investigation by a maximum entropy method further attests that the covalent hybridization of Pb/Bi–O bonds plays a vital role in the improved ferroelectricity and interacts with thermal vibration to dominate the crossover from positive to negative thermal expansion. The present studies would give direct evidence to verify the theoretical calculations and could be extended to reveal the nature of thermal expansion in ferroelectrics.