Study of the behaviour of the dielectric constant in Cu,Fe:BaTiO_3

作     者：Alioune OUEDRAOGO Kalifa PALM Issaka OUEDRAOGO Guy CHANUSSOT 

作者机构：Laboratory of Applied Organic Chemistry and Physics UFR/SEA University of Ouagadougou BP 7021 Ouagadougou Burkina Faso Laboratory of Dielectrics University of Dijon 21000 Dijon France) 

出 版 物：《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 (浙江大学学报（英文版）A辑（应用物理与工程）)

年 卷 期：2008年第9卷第3期

页      面：429-434页

核心收录：

学科分类：0810[工学-信息与通信工程] 081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 070301[理学-无机化学] 0812[工学-计算机科学与技术（可授工学、理学学位）] 

主　　题：电容率 铜 化合物 晶体 

摘      要：In this work we study the behaviour of the dielectric constant of BaTiO3 single crystals doped with Cu and Fe for different ion percentages, particularly, the influence of these heterovalent substitutions on the ferroelectric-paraelectric phase transition whose temperature is found at Tc=120 °C for pure samples. The dielectric constant ε in terms of temperature shows that the Curie temperature decreases when the quantity of impurities increases and presents a broadening and flattering of the maxi-mum of ε(T) within higher values, with the transition becoming more and more diffuse. It is interesting to have a material with very high permittivity (high-k) because of its capacity to store an important quantity of electric charges. The ε anisotropy and the Curie-Weiss law are also verified with a good ratio between the slopes of ε-1(T) from both sides of the transition, leading to a Curie constant:C=13×104 K for BaTiO3:1.6%Fe in the polar phase. BaTiO3 is a displacive ferroelectric going through a first-order phase transition. The substitutions have an effect on the dynamics of the perovskite lattice. They induce charges transfer to Ti and a diminution of elastic forces in BaTiO3. Then we discuss the fact that the maximum of permittivity does not depend on the phase transition but on the nature of the material.