Sr_2Bi_(4-x/3)Ti_(5-x)Nb_xO_(18)陶瓷的铁电介电性能  

The ferroelectric and dielectric properties of Sr_2Bi_(4-x/3)Ti_(5-x)Nb_xO_(18) ceramics

作　　者：沈柏清[1] 孙慧[1] 陈小兵[1] 

机构地区：[1]扬州大学物理科学与技术学院,江苏扬州225002

出　　处：《扬州大学学报（自然科学版）》2004年第4期36-39,共4页Journal of Yangzhou University：Natural Science Edition

基　　金：国家自然科学基金资助项目(10274066)

摘　　要：对Sr2Bi4-x/3Ti5-xNbxO18(x=0,0.003,0.018,0.048,0.096)陶瓷样品的铁电和介电性能进行了测量.结果表明,Sr2Bi4Ti5O18样品的剩余极化2Pr为0.22 C·m-2,少量Nb掺杂可使样品的2Pr有明显提高,当x=0.018时,2Pr达到最大为0.34 C·m-2.介电损耗随温度的变化关系曲线上存在P1,P2,P3 3个介电损耗峰,分别在70,230,290℃附近.低温部分的2个损耗峰具有介电弛豫的特征,其弛豫机制被认为是点缺陷与畴界之间的相互作用.通过激活参数的计算以及损耗峰随不同Bi过量的变化,可以确定P1,P2峰的弛豫机制与Sr,Ti空位有关.随着Nb掺杂量的增加,P1,P2峰逐渐降低,表明Nb掺杂降低了样品中缺陷的浓度,从而使得样品的2Pr明显提高.The ferroelectric and dielectric properties of niobium doped Sr2Bi4Ti5O18 ceramics were examined. A small amount of niobium doping results in a remarkable increase in the remnant polarization, the 2Pr of Sr2Bi4Ti5O18 is about 0. 22 C·m-2, and it reaches a maximum value of 0. 34 C·m-2 when x is 0. 018. Two relaxation peaks (P1,P2) are found on the D (tc) curves at 70 ℃ and 230 ℃ respectively. It is proposed that the peaks on the D (tc) curves are due to the interaction of domain boundaries and charged point defects. The calculation of activation parameter and the dependence of peaks P1 and P2 on Bi2O3 excess indicated that the relaxation mechanism of P1 and P2 are related to stoichiometric vacancies of strontium-titanium. With niobium doping the peaks P1 and P2 almost disappear gradually. It indicates that small amounts of niobium doping could decrease the concentration of oxygen and strontium-titanium vacancies, which would be responsible for the increase in 2P_r

关 键 词：铁电 陶瓷 掺杂 剩余极化 介电损耗 点缺陷 

分 类 号：O482.54[一般工业技术—材料科学与工程] TM271.4[理学—固体物理]