Ferroelectric Transition and Curie-Weiss Behavior in Some Filled Tungsten Bronze Ceramics  

作　　者：朱晓莉 陈湘明 

机构地区：[1]Laboratory of Dielectric Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027

出　　处：《Chinese Physics Letters》2014年第1期110-114,共5页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China under Grant Nos 51102210 and 51332006.

摘　　要：Ferroelectric transitions in filled tungsten bronze ceramics Sr4R2Ti4Nb6O30, Sr5RTi3NbT030 （R=La, Nb, Sm ＆ Eu） and Ba4Nd2Ti4Nb6030 are investigated with differential scanning calorimetry （DSC） and the Curie- Weiss law fitting to the dielectric constant. The magnitude of the Curie Weiss constant C - 105 suggests displacement-type ferroelectric transition in the present compounds. The large AT difference between dielectric maximum temperature Tm and Curie-Weiss temperature To） values indicate the difficult formation of ferroeleetric domains or polar nanoregions in the present compounds and also the characteristics of the first order ferroelectric transition. Three categories are suggested for the ferroelectric transition in the above tungsten bronzes. The ferroelectric transition exhibits large thermal hysteresis. According to the DSC results, gradual recovery of the endothermic peak occurs after aging at temperature below the Curie point, indicating the gradual stability of the ferroelectric phase after cooling from the high-temperature para-electric phase. The relationship between the Curie- Weiss law fitting parameters and the nature of the ferroelectric transition is modified for the filled tungsten bronzes.Ferroelectric transitions in filled tungsten bronze ceramics Sr4R2Ti4Nb6O30, Sr5RTi3NbT030 （R=La, Nb, Sm ＆ Eu） and Ba4Nd2Ti4Nb6030 are investigated with differential scanning calorimetry （DSC） and the Curie- Weiss law fitting to the dielectric constant. The magnitude of the Curie Weiss constant C - 105 suggests displacement-type ferroelectric transition in the present compounds. The large AT difference between dielectric maximum temperature Tm and Curie-Weiss temperature To） values indicate the difficult formation of ferroeleetric domains or polar nanoregions in the present compounds and also the characteristics of the first order ferroelectric transition. Three categories are suggested for the ferroelectric transition in the above tungsten bronzes. The ferroelectric transition exhibits large thermal hysteresis. According to the DSC results, gradual recovery of the endothermic peak occurs after aging at temperature below the Curie point, indicating the gradual stability of the ferroelectric phase after cooling from the high-temperature para-electric phase. The relationship between the Curie- Weiss law fitting parameters and the nature of the ferroelectric transition is modified for the filled tungsten bronzes.

分 类 号：TQ174[化学工程—陶瓷工业] TQ174.758[化学工程—硅酸盐工业]