The use of refrigeration technology is widespread in national security, industrial and agricultural production, biomedicine, and everyday life. High efficiency, environmental friendliness, and low cost make solid-state refrigeration based on electrocaloric effect (ECE) a promising refrigeration technology. Lead-free ferroelectric ceramics (1–x)Ba(Zr_0.2Ti_0.8)O₃–x(Ba_0.7Ca_0.3)TiO₃ (BZT–BCT) are promising materials for electrocaloric refrigeration in the field. In this paper, Sm-doped 0.5BZT–0.5BCT ceramic was fabricated by the conventional solid-state reaction method. The effect of Sm-doping contents (0, 1.0, 2.0, 2.5, and 3.0 mol.%) on the phase structures, dielectric properties, ferroelectricity, and electrocaloric properties of 0.5BZT–0.5BCT ceramics was systematically examined. The results indicate that all ceramics have a pure perovskite structure with no other secondary phase available. High relative densities are observed in all lead-free ferroelectric ceramics and all of the samples show transgranular fracture with no clear grain boundaries seen. The ceramics’ ferroelectric hysteresis loops become thinner as the Sm doping content increases. At that, remanent polarization Pr decreases, indicating that more polar nanoregions (PNRs) are formed in BZT–BCT lead-free ceramics through Sm doping. The increase in Sm doping content resulted in a change in the dielectric permittivity and electrocaloric temperature that first increased and then decreased. The maximum dielectric permittivity is 5,518 when the doping content of Sm is 2.5 mol.% and the maximum electrocaloric temperature change ΔT_max of 0.109 K at 4 kV/mm was obtained when Sm doping content was 2 mol.%. The results show that an appropriate Sm doping is favorable for improving the dielectric, ferroelectric, and electrothermal properties of lead-free ceramics 0.5BZT–0.5BCT.

制冷技术的运用广泛应用于国家安全、工农业生产、生物医药、日常生活等领域。高效、环保、低成本使得基于电热效应（ECE）的固态制冷成为一种很有前景的制冷技术。无铅铁电陶瓷(1–x)Ba(Zr _0.2 Ti _0.8 )O ₃ –x(Ba _0.7 Ca _0.3 )TiO ₃ (BZT–BCT)是该领域很有前景的电热制冷材料。本文采用常规固相反应方法制备了 Sm 掺杂 0.5BZT–0.5BCT 陶瓷。系统研究了 Sm 掺杂含量（0、1.0、2.0、2.5 和 3.0 mol.%）对 0.5BZT–0.5BCT 陶瓷的相结构、介电性能、铁电性和电热性能的影响。结果表明，所有陶瓷都具有纯钙钛矿结构，没有其他第二相。在所有无铅铁电陶瓷中观察到高相对密度，并且所有样品都显示出穿晶断裂，没有看到清晰的晶界。随着Sm掺杂含量的增加，陶瓷的铁电磁滞回线变得更薄。此时，剩余极化Pr降低，表明通过Sm掺杂在BZT-BCT无铅陶瓷中形成了更多的极性纳米区（PNR）。Sm掺杂含量的增加导致介电常数和电热温度先升高后降低。当Sm掺杂含量为2.5 mol.%时，最大介电常数为5,518 ；当Sm掺杂含量为2 mol.%时，在4 kV/mm下获得最大电热温度变化ΔT _{max 0.109 K。}结果表明，适当的Sm掺杂有利于提高无铅陶瓷0.5BZT–0.5BCT的介电、铁电和电热性能。