0.7BiFeO_(3)-0.3BaTiO_(3)陶瓷中极化翻转产生的巨电卡效应增加及Mn^(4+)离子掺杂对其介电、铁电性能的影响  

Giant electrocaloric effect enhancement due to the polarization flip and influence of Mn^(4+)doping on the dielectric,ferroelectric properties in 0.7BiFeO_(3)-0.3BaTiO_(3) ceramics

作　　者：汤卉 牛翔 杨志朋 彭小草 赵小波 姚英邦 陶涛 梁波 唐新桂[2] 鲁圣国 Tang Hui;Niu Xiang;Yang Zhi-Peng;Peng Xiao-Cao;Zhao Xiao-Bo;Yao Ying-Bang;Tao Tao;Liang Bo;Tang Xin-Gui;Lu Sheng-Guo(Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter,Guangdong Provincial Research Center on Smart Materials and Energy Conversion Devices,School of Materials and Energy,Guangdong University of Technology,Guangzhou 510006,China;School of Physics and Optoelectronic Engineering,Guangdong University of Technology,Guangzhou 510006,China)

机构地区：[1]广东工业大学材料与能源学院,广东省智能材料和能量转化器件工程技术研究中心,广东省功能软凝聚态物质重点实验室,广州510006 [2]广东工业大学物理与光电工程学院,广州510006

出　　处：《物理学报》2022年第14期280-289,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51372042,51872053);广东省自然科学基金(批准号:2015A030308004);国家自然科学基金-广东联合基金(批准号:U1501246);东莞市核心技术攻关前沿项目(批准号:2019622101006);先进能源科学与技术广东省实验室佛山分中心暨佛山仙湖实验室开放基金重点项目(批准号:XHT2020-011)资助的课题.

摘　　要：BiFeO_(3)(BFO)作为反铁磁性和铁电性共存的多铁性材料,其饱和极化强度理论值大于100μC/cm^(2),居里温度为830℃,具有较强的电卡效应.但是由于BFO高温烧结过程中Bi_(2)O_(3)易挥发,铁离子易变价,导致BFO中缺陷较多,漏电流较大,其铁电特性难以发挥出来.虽然采用与BaTiO_(3)(BTO)等氧化物铁电体形成固溶体的方法可以减小漏电流,但是漏电流和高介电损耗问题仍然存在.本文试图通过添加锰离子到BFO-BTO固溶体的方法解决这一问题.采用传统的高温固相反应法制备了0.7BiFeO_(3)-0.3BaTiO_(3)+x%MnO_(2)(BFO-BTO+x%MnO_(2),其中x%为质量分数)陶瓷,研究了MnO_(2)掺杂对BFO-BTO固溶体的微观结构、介电和铁电性能的影响.值得注意的是,BFO-BTO+x%MnO_(2)样品测试结果证明少量掺杂MnO_(2)能降低BFO-BTO陶瓷的介电损耗和漏电流,这是由于掺杂Mn^(4+)补偿氧空位浓度所致.另外,0.7BFO-0.3BTO+0.5%MnO_(2)陶瓷在100 kV/cm时的最大极化强度达到50.53μC/cm^(2).最后利用热电偶直测法测试了BFO-BTO+x%MnO_(2)陶瓷的电卡效应,发现极化翻转方法能使BFO-BTO+x%MnO_(2)陶瓷的电卡效应翻倍增大,其中x=0样品从0至-30 kV/cm的变化与30 kV/cm至0的电场变化相比,增大近8倍,并且证实该方法同样适用于多晶一级相变铁电体.As a kind of ferroelectric and antiferromagnetic coexistent multi-ferroic material,BiFeO_(3)(BFO)has a theoretical saturation polarization over 100μC/cm^(2),and a Curie temperature of 830℃,which may offer a huge electrocaloric effect.However,owing to the evaporation of Bi_(2)O_(3) in the sintering process at high temperatures and the variation of chemical valence of iron ions,there are lots of point defects and also a large leakage current existing in BFO,making the ferroelectricity of BFO hard to develop and measure.Although the forming of solid solution with BaTiO_(3)(BTO)or other oxide ferroelectrics may mitigate the leakage current,high loss tangent is still existent.This work tries to address this issue by adding manganese ions into the BFO-BTO solid solution.The 0.7(BFO)-0.3(BTO)+x%MnO_(2) ceramics are prepared through using the conventional solid-state reaction at high temperature.The microstructure,dielectric characteristic and ferroelectric characteristic are investigated by doping different Mn^(4+)ions.Results indicate that the crystallographic structure is of rhombohedral and pseudocubic phase coexistence.It is observed that a certain content of Mn^(4+)ions may lead both the loss tangent and the leakage current for BFO-BTO ceramic to decrease,which is due to the compensation of dopant Mn^(4+)ions for the oxygen vacancies.In addition,the 0.7BFO-0.3BTO+0.5%MnO_(2) ceramic arrives at a maximum polarization of 50.53μC/cm^(2) at 100 kV/cm.Finally,a direct approach is used to measure the electrocaloric effect.It is found that using the polarization flip method,the ECE temperature change is observed to increase almost 8 times when the electric field changes from 0 to-30 kV/m with respect to that when the electric field decreases from 30 kV/cm to 0.This verifies that the Lu et al’s method is also applicable to polycrystalline first-order phase transition ferroelectrics.

关 键 词：铁电体 介电损耗 电卡效应 

分 类 号：TB34[一般工业技术—材料科学与工程]