Dual-peak electrocaloric effect (ECE) exists over a broad range significantly below Curie temperature in co-mixed SrBi_1.98La_0.02Nb_2–x Ta _x O₉ (SBLNT) compositions exhibiting diffused phase transition. The indirect measurement method is used to study the influence of defect-modified potential barrier distributions on the ECE of lead-free SBLNT ceramics. Variation in isothermal entropy change and adiabatic temperature change with varying tantalum (Ta) content signify effects of morphology and impact of altered potential barriers in the parent lattice without involving structural phase transition. A unique appearance of twin-peak positive–negative ECE in equally doped SrBi_1.98La_0.02Nb-TaO₉ matrix is attributed to doping-induced formation of polar nanoregions and distinct dipole switching mechanisms controlled by evenly distributed Nb–Ta potential barriers in SBLNT lattice. Higher doping concentration reduces porosity and promotes electric polarization, thereby the relative cooling power gradually increases with increasing Ta at Nb sites.

中文翻译：

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扩散 SrBi1.98La0.02Nb2−x Ta x O9 材料铁电相中的双峰电热效应

双峰电热效应 (ECE) 在显着低于居里温度的混合 SrBi _1.98 La _0.02 Nb _{2– x} Ta _x O ₉ (SBLNT) 组合物中存在广泛的范围，表现出扩散相变。采用间接测量方法研究缺陷修正势垒分布对无铅SBLNT陶瓷ECE的影响。等温熵变和绝热温度随钽 (Ta) 含量的变化而变化，这表明母晶格中改变的势垒对形态的影响和影响，而不涉及结构相变。在等量掺杂的 SrBi _1.98中双峰正负 ECE 的独特外观 La _0.02 Nb-TaO ₉基体归因于掺杂诱导形成的极性纳米区域和由 SBLNT 晶格中均匀分布的 Nb-Ta 势垒控制的独特偶极开关机制。较高的掺杂浓度会降低孔隙率并促进电极化，从而随着 Nb 位点的 Ta 增加，相对冷却能力逐渐增加。