KBT CuW铁电陶瓷晶粒异常生长和巨介电性能研究

Abnormal Grain Growth and Giant Dielectric Properties of KBT CuW Ferroelectric Ceramics

为了探究Cu/W掺杂对K_(0.5)Bi_(4.5)Ti_(4)O_(15)(KBT)铁电陶瓷显微组织和介电性能的影响,文中采用固相反应法制备了K_(0.5)Bi_(4.5-x)Ti_(4-x)(Cu_(0.5)W_(0.5))_(2 x)O_(15)(KBT-CuW_(x),x分别为0.00,0.01,0.02,0.03)陶瓷。采用X射线衍射分析仪表征陶瓷的相结构,扫描电子显微镜分析陶瓷的显微组织形貌,利用精密阻抗分析仪测试室温下不同频率(100 Hz~107 Hz)的介电常数ε′和介电损耗tanδ,并测试不同温度(303~453 K)下的阻抗谱,最后利用Arrhenius公式计算得到KBT-CuW陶瓷电导率和温度关系。研究结果表明:KBT-CuW陶瓷为正交相结构并且伴有异常长大的晶粒出现;随着Cu^(2+)和W^(6+)含量的增加,陶瓷中大晶粒尺寸逐渐减小,数量逐渐增加,其介电常数显著提高,x=0.03陶瓷在100 Hz下介电常数达到了106;KBT-CuW陶瓷的低频巨介电响应与异常长大晶粒引起的缺陷偶极子和界面响应有关。

K_(0.5)Bi_(4.5-x)Ti_(4-x)(Cu_(0.5)W_(0.5))_(2 x)O_(15)(KBT-CuW_(x),x=0.00,0.01,0.02,0.03)ceramics was synthesized by the solid state reaction method.The effects of Cu/W co doped ions on the microstructure and dielectric properties of K_(0.5)Bi_(4.5)Ti_(4)O_(15)(KBT)ferroelectric ceramics were examined.Its phase structure was characterized by an X ray diffraction analyzer(XRD).Its microstructure was analyzed by a scanning electron microscope(SEM).Its dielectric constantε′and dielectric loss tanδat different frequencies(100~107 Hz)were measured by a precision impedance analyzer at room temperature,and its impedance spectra were measured at different temperatures(303~453 K).Finally,the relation between conductivity of KBT-CuW ceramics and temperature was calculated by using Arrhenius formula.The results show that KBT-CuW ceramics have an orthorhombic phase structure and abnormally grown grains.With an increase in the content of Cu^(2+)and W^(6+),there is a gradual decrease in the size of large grains,a gradual increase in their number,and a significant increase in the ceramics’dielectric constant,which(x=0.03)reached 106 at 100 Hz.The low frequency giant dielectric response of KBT-CuW ceramics is related to the defect dipoles and interface response caused by the abnormally large grains.