Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel.
Department of Materials Science and Chemical Engineering, Stony Brook University, NY, USA.
Adv Mater. 2018 Oct;30(41):e1707455. doi: 10.1002/adma.201707455. Epub 2018 Jul 8.
Room-temperature mechanical properties of thin films and ceramics of doped and undoped ceria are reviewed with an emphasis on the anelastic behavior of the material. Notably, the unrelaxed Young's modulus of Gd-doped ceria ceramics measured by ultrasonic pulse-echo techniques is >200 GPa, while the relaxed biaxial modulus, calculated from the stress/strain ratio of thin films, is ≈10 times smaller. Oxygen-deficient ceria exhibits a number of anelastic effects, such as hysteresis of the lattice parameter, strain-dependent Poisson's ratio, room-temperature creep, and nonclassical electrostriction. Methods of measuring these properties are discussed, as well as the applicability of Raman spectroscopy for evaluating strain in thin films of Gd-doped ceria. Special attention is paid to detection of the time dependence of anelastic effects. Both the practical advantages and disadvantages of anelasticity on the design and stability of microscopic devices dependent on ceria thin films are discussed, and methods of mitigating the latter are suggested, with the aim of providing a cautionary note for materials scientists and engineers designing devices containing thin films or bulk ceria, as well as providing data-based constraints for theoreticians who are involved in modeling of the unusual electrical and electromechanical properties of undoped and doped ceria.
掺杂和未掺杂氧化铈薄膜和陶瓷的室温力学性能综述，重点介绍材料的滞弹性行为。值得注意的是，通过超声脉冲回波技术测量的 Gd 掺杂氧化铈陶瓷的未弛豫杨氏模量>200GPa，而通过薄膜应力/应变比计算的松弛双轴模量则小约 10 倍。缺氧氧化铈表现出多种滞弹性效应，例如晶格参数滞后、应变相关泊松比、室温蠕变和非经典电致伸缩。讨论了测量这些性能的方法，以及拉曼光谱在评估 Gd 掺杂氧化铈薄膜应变中的适用性。特别关注对滞弹性效应时间依赖性的检测。讨论了滞弹性对依赖氧化铈薄膜的微观器件设计和稳定性的实际优缺点，并提出了减轻后者的方法，目的是为设计含有薄膜或块状氧化铈的器件的材料科学家和工程师提供警示，并为涉及未掺杂和掺杂氧化铈异常电和机电性能建模的理论提供基于数据的约束。
