聚合物热解法制备高击穿场强CaCu_(3)Ti_(4)O_(12)陶瓷的微观结构及介电性能

Microstructure and Dielectric Properties of CaCu_(3)Ti_(4)O_(12) Ceramics with High Breakdown Strength Prepared via Polymer Pyrolysis

由于CaCu_(3)Ti_(4)O_(12)(CCTO)陶瓷表现出非欧姆特性,这些陶瓷有望用于储能电容器和过压保护装置等应用,然而一般制备的CCTO陶瓷样品击穿场强(E_(b))极低。为了提高CCTO陶瓷样品的E_(b),本文以硝酸铜、硝酸钙、二钛酸二异丙酯为原料,丙烯酸水溶液作为聚合单体,过硫酸铵水溶液作为引发剂,采用聚合物热解法制备了CCTO前驱体粉末,然后分别在1040、1060、1080℃烧结得到CCTO陶瓷样品,研究了不同烧结温度陶瓷样品的相结构、微观结构和介电性能。结果表明:在不同烧结温度下采用聚合物热解法制备的陶瓷样品在保持高介电常数的同时大幅提高了E_(b),在1060℃下烧结的陶瓷样品介质损耗降低,其E_(b)为11.45 kV/cm,介电常数和介质损耗因数分别为9110和0.03。在1060℃下烧结有利于样品晶粒正常生长,完善晶界及形成势垒。此外,晶粒的正常生长对陶瓷样品的介电常数有显著影响,晶界阻抗的增大有利于E_(b)的提高和低频介质损耗的降低。

CaCu_(3)Ti_(4)O_(12)(CCTO)ceramics have a promising application in energy storage capacitors and over voltage protection devices because of their non-Ohmic property.However,the breakdown strength(E_(b))of commonly prepared ceramic samples is extremely low.In order to increase the E_(b) of the CCTO ceramic,we prepared a CCTO precursor powder by polymer pyrolysis with copper nitrate,calcium nitrate,and diisopropyl dititanate as raw materials,aqueous acrylic acid as polymerization monomer,and aqueous ammonium persulfate as initiator.Then the CCTO ceramic samples were prepared through sintering at 1040,1060,and 1080℃,respectively.The phase structure,microstructure,and dielectric properties of the ceramic samples at different sintering temperatures were studied.The results show that the E_(b) of ceramic samples prepared by polymer pyrolysis at different sintering temperatures increases greatly while maintaining high dielectric constant.The dielectric loss of ceramic samples sintered at 1060℃ is reduced,and its E_(b) is 11.45 kV/cm,its dielectric constant and dielectric loss factor are about 9110 and 0.03,separately.Sintering at 1060℃ is beneficial to normal grain growth,improving the grain boundary and forming potential barrier.In addition,the normal grain growth has a significant effect on the dielectric constant of ceramic samples,and the increase of grain boundary impedance is beneficial to the increase of E_(b) and the decrease of low frequency dielectric loss.