Pan Zhao, Jiang Xingxing, Yu Runze, Ren Yang, Lin Zheshuai, Chen Jun, Azuma Masaki, Xing Xianran
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Center for Crystal R&D, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
ACS Appl Mater Interfaces. 2022 May 11. doi: 10.1021/acsami.2c00771.
Controlling negative thermal expansion (NTE) is an important topic in the study of NTE materials. Generally, a large magnitude of NTE with a wide NTE operation temperature window is preferable for applications of NTE materials, as a stronger NTE can be used to tailor the coefficient of thermal expansion (CTE) of materials with positive thermal expansion by forming composites more efficiently. However, controlling the NTE in single-phase materials is still a significant challenge. In present study, we proposed a promising method to control the thermal expansion from large volume contraction in a limited temperature widow ( = 0, Δ = -4.8%, 675-700 °C) to a nonlinear strong NTE over a wider temperature range ( = 0.8, α̅ = -6.12 × 10/°C, RT to 600 °C) by means of adjusting the proportion of cations with different ferroelectric activities in 0.5PbTiO-0.5Bi(CoFe)O ferroelectrics. The obtained NTE was stronger than many of the currently available NTE materials, and the operation window of NTE was also in an extended temperature range. The unusual transformation is well explained by the spontaneous volume ferroelectrostriction effect, which was evidenced by joint experimental and theoretical studies. The present work not only may pave the way for controllable large NTE in PbTiO-based ferroelectrics but also could be extended to magnetic NTE materials, whose NTE is coupled with magnetism.
控制负热膨胀（NTE）是NTE材料研究中的一个重要课题。一般来说，对于NTE材料的应用而言，具有较宽NTE工作温度窗口的大幅度NTE是较为理想的，因为更强的NTE可通过更有效地形成复合材料来调整具有正热膨胀的材料的热膨胀系数（CTE）。然而，在单相材料中控制NTE仍然是一项重大挑战。在本研究中，我们提出了一种有前景的方法，通过调整0.5PbTiO₃-0.5Bi(CoFe)O₃铁电体中具有不同铁电活性的阳离子比例，将热膨胀从有限温度窗口（T₀ = 0，ΔV/V = -4.8%，675 - 700℃）下的大体积收缩控制为在更宽温度范围（T₀ = 0.8，α̅ = -6.12×10⁻⁶/℃，室温至600℃）内的非线性强NTE。所获得的NTE比许多目前可用的NTE材料更强，并且NTE的工作窗口也处于扩展的温度范围内。这种不寻常的转变通过自发体积铁电致伸缩效应得到了很好的解释，这一点得到了实验和理论联合研究的证实。本工作不仅可能为基于PbTiO₃的铁电体中可控的大NTE铺平道路，而且还可以扩展到其NTE与磁性耦合的磁性NTE材料。
