The electric-field-induced and temperature induced dynamics of domains, defects, and phases play an important role in determining the macroscopic functional response of ferroelectric and piezoelectric materials. However, distinguishing and quantifying these phenomena remains a persistent challenge that inhibits our understanding of the fundamental structure-property relationships. In situ dark field x-ray microscopy is a new experimental technique for the real space mapping of lattice strain and orientation in bulk materials. In this paper, we describe an apparatus and methodology for conducting in situ studies of thermally and electrically induced structural dynamics and demonstrate their use on ferroelectric BaTiO3 single crystals. The stable temperature and electric field apparatus enables simultaneous control of electric fields up to ≈2 kV/mm at temperatures up to 200 °C with a stability of ΔT = ±0.01 K and a ramp rate of up to 0.5 K/min. This capability facilitates studies of critical phenomena, such as phase transitions, which we observe via the microstructural change occurring during the electric-field-induced cubic to tetragonal phase transition in BaTiO3 at its Curie temperature. With such systematic control, we show how the growth of the polar phase front and its associated ferroelastic domains fall along unexpected directions and, after several cycles of electric field application, result in a non-reversible lattice strain at the electrode-crystal interface. These capabilities pave the way for new insights into the temperature and electric field dependent electromechanical transitions and the critical influence of subtle defects and interfaces.

中文翻译：

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使用暗场 X 射线显微镜对电活性材料中的微结构动力学和应变场进行原位成像

畴、缺陷和相的电场诱导和温度诱导动力学在确定铁电材料和压电材料的宏观功能响应方面起着重要作用。然而，区分和量化这些现象仍然是一个持续的挑战，阻碍了我们对基本结构-性质关系的理解。原位暗场 X 射线显微镜是一种新的实验技术，用于对散装材料中的晶格应变和取向进行真实空间映射。在本文中，我们描述了一种用于进行热和电诱导结构动力学的原位研究的设备和方法，并展示了它们在铁电 BaTiO3 单晶上的应用。稳定的温度和电场装置能够在高达 200 °C 的温度下同时控制高达 ≈2 kV/mm 的电场，稳定性为 ΔT = ±0.01 K，斜率高达 0.5 K/min。这种能力有助于研究临界现象，例如相变，我们通过在 BaTiO3 居里温度下电场诱导立方到四方相变期间发生的微观结构变化来观察相变。通过这种系统控制，我们展示了极性相前沿及其相关铁弹性域的生长如何沿意想不到的方向下降，并在施加几次电场循环后，在电极-晶体界面处产生不可逆的晶格应变。