Design of Shape Memory Ceramics: Principles, Strategies and Perspectives

Shape memory ceramics (SMCs) are regarded as stimulus-responsive intelligent materials, capable of a martensitic phase transformation under the stimuli of temperature and/or stress fields. Research efforts spanning more than 40 years since the 1970 s, have endowed these ceramics with tunable transformation properties, whilst the strain recovery and reversibility are hindered by their significant brittleness. This review first provides a brief introduction and the fundamentals on SMCs. General principles are then proposed to tackle the outstanding issue of brittleness by regulating the transformation-induced lattice strain. Specifically, the intrinsic approaches accommodate the transformation-induced lattice strain by lattice engineering or compositing, and extrinsic approaches release the transformation-induced lattice strain by materials miniaturization and architecting. Following the general principles, the above four state-of-the-art design strategies and associated implementations are critically reviewed. Towards deliberate des-ignability and applications in sensing, actuation, and energy dissipation, this review points out the challenges and future directions in developing new-generation SMCs.