具有复合钙钛矿结构的(Pb,La)(Zr,Sn,Ti)O3(简称PLZST)弛豫反铁电材料在特定的外电场、温度或应力作用下，可以被诱导出反铁电相与铁电相之间的相变，表现出优异的场致应变、热释电和电卡等性能，在精密致动、固态制冷和热释电探测等领域具有广泛的应用前景。长期以来，对于PLZST反铁电材料的组分、结构、性能与场致相变行为之间的关系研究一直是新型功能材料领域的热点。本论文尝试通过系统探讨PLZST弛豫反铁电材料的场致相变行为对其应变、热释电与电卡效应的影响规律，为开发高性能反铁电材料提供实验依据和理论借鉴。 反铁电材料的应变温度稳定性一直是制约其应用发展的瓶颈之一，本论文选取具有四方反铁电相结构的PLZST反铁电陶瓷作为研究对象，对极化前后的(Pb0.97La0.02(Zr0.85Sn0.08Ti0.07)O3反铁电陶瓷的场致应变行为和应变温度稳定性进行了对比研究。实验发现，极化后PLZST反铁电陶瓷在超宽温度区间(20 ℃-190 ℃)内均可保持约0.4 %的应变响应，应变偏差值保持在± 5.5 %范围。理论分析发现，特殊的场致应变行为与极化后PLZST反铁电陶瓷中所形成的择优取向的反铁电畴有关。 采用助熔剂法生长了具有四方相结构的PLZST反铁电单晶，[001]切型四方相PLZST反铁电单晶可表现出2.08 K的电卡绝热温变，电卡强度可达0.416 K mm/kV，绝热温变峰值在60 ℃附近。通过制备[001]、[011]和[111]切型的PLZST反铁电单晶样品，系统研究了四方相PLZST反铁电单晶的电卡效应的各向异性。其中，[111]切型PLZST反铁电单晶能够在约36 ℃的宽温区范围内保持ΔT > 2 K的电卡绝热温变。 在准同型相界(MPB)附近组分PLZST反铁电单晶中实现了温区展宽约为50 ℃的热释电响应。研究发现，热释电响应温区的展宽与两相共存的MPB附近组分PLZST反铁电单晶中分区域、分步完成的退极化过程有关。

(Pb,La)(Zr,Sn,Ti)O3 (PLZST) relaxor antiferroelectric (AFE) materials with complex perovskite structure have rich phase transformations between AFE phase and ferroelectric (FE) phase under external electric field, temperature and stress. The phase transformations generally lead to outstanding field-induced strain, pyroelectric and electrocaloric performance, which make the PLZST system very promising in the application fields of high-sensitive actuators and transducers, solid-state cooling and pyroelectric detectors. The relationship among the composition, structure, property and field-induced phase transition behavior of PLZST AFE materials has been a hot topic in research area of multifunctional materials. The effects of the field-induced phase transition behavior on the field-induced strain、pyroelectric and electrocaloric properties of PLZST AFE materials were deeply discussed here, which may provide experimental evidence and theoretical reference for the development of high-performance antiferroelectric materials. The temperature stability of field-induced strain of the AFE materials is always one of the bottlenecks restricting the development of their applications. PLZST AFE ceramics with tetragonal phase structure were chosen as the research objects, field-induced strain and temperature stability of the virgin and poled (Pb0.97La0.02)(Zr0.85Sn0.08Ti0.07)O3 AFE ceramics were compared and studied systematically. It was discovered that the strain response of ~0.4 % in a wide temperature range (20 ℃-190 ℃) was achieved in the poled PLZST AFE ceramics, and the fluctuation of field-induced strain remained within ± 5.5 %. Theoretical analysis showed that the strain response was related to the preference-oriented antiferroelectric domains formed in the poled PLZST AFE ceramics. PLZST AFE single crystals with tetragonal phase structure were grown by flux method. Enhanced electrocaloric effects were obtained in [001]-oriented PLZST AFE single crystals, the maximum adiabatic temperature change was 2.08 K, the electrocaloric coefficient was 0.416 K mm/kV, and the corresponding temperature is around 60 ℃. Besides, [001]-, [011]- and [111]-oriented samples were prepared for the research on the anisotropy of electrocaloric effects. Adiabatic temperature change (ΔT > 2 K) with a wide temperature span of 36 ℃ was achieved in [111]-oriented tetragonal PLZST AFE single crystals. A broad pyroelectric response with temperature range of 50 ℃ was obtained in the PLZST single crystals with composition near the morphotropic phase boundary (MPB). Further study showed that the broad pyroelectric response was closely related to the multi-step depolarization process in the MPB-based PLZST AFE single crystals.