高等学校化学学报

高等学校化学学报 ›› 2004, Vol. 25 ›› Issue (7): 1218.

• 研究简报 • 上一篇    下一篇

类钙钛矿新铌酸盐Ba5LaTi2Nb3O18的合成、结构与介电特性

方亮, 张辉, 孟范成, 洪学鹍, 刘韩星, 袁润章   

  1. 武汉理工大学材料复合新技术国家重点实验室, 武汉 430070
  • 收稿日期:2003-08-26 出版日期:2004-07-24 发布日期:2004-07-24
  • 通讯作者: 方 亮(1970年出生),男,博士,教授,博士生导师.从事无机功能材料的合成、结构与性能研究.E-mail:fangliang001@263.net E-mail:fangliang001@263.net
  • 基金资助:

    国家自然科学基金(批准号:50002007);教育部重大科学研究项目(批准号:0201);国际衍射数据中心(ICDD);Grant-in-Aid基金(批准号:02-05,02-40)资助

Synthesis, Structure and Dielectric Properties of a New Pervoskite-related Niobate Ba5LaTi2Nb3O18

FANG Liang, ZHANG Hui, MENG Fan-Cheng, HONG Xue-Kun, LIU Han-Xing, YUAN Run-Zhang   

  1. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
  • Received:2003-08-26 Online:2004-07-24 Published:2004-07-24

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摘要： 为满足现代通信技术小型化、集成化与高可靠性的迫切要求,探索具有高介电常数、低介电损耗与低温度系数的微波介电材料引起了材料科学、化学、物理和电子科学等领域科学工作者的广泛关注,并已开发出复合钙钛矿结构的Ba(Mg1/3Ta2/3)O3、Ba(Zn1/3Ta2/3)O3和钨青铜结构的Ba6-3xLn8+2x·Ti18O54及Ba2Ti9O20等实用化的高性能材料[1～7].这类材料均由氧八面体共顶连接,而且氧八面体内(B位)、外(A位)阳离子比例等于或略大于1,由此,我们推测在B位与A位阳离子比例略小于1的类钙钛矿结构中也极有可能存在具有优良介电性能的新材料,因此对通式为AnBn-1O3n(n=5,6,7,8)的系列新化合物进行了系统的合成、结构与介电性能研究[8,9].本文报道在BaO-La2O3-TiO2-Nb2O5体系中合成的具有5层类钙钛矿结构的新铌酸盐Ba5LaTi2Nb3O18,发现该材料具有较好的介电性能.

Abstract: A New Niobate Ba5LaTi2Nb3O18 was synthesized by a high temperature solid state reaction in the BaO-La2O3-TiO2-Nb2O5 system. The chemical compositions, crystal structure, microstructure, density and melting point of the new compound were characterized by EPMA, XRD, SEM, DTA and so on. Ba5LaTi2Nb 3O18 crystallizes the rhombohedral system with unit cell parameters a=0 573 25(2) nm, c=4 213 9(2) nm, and space group R3m, Z=3. The structure may be described as five (Nb,Ti)O6 octahedra corner-sharing along c axis to form perovskite layer connected by Ba atoms. The Ba5LaTi2Nb3O18 ceramic exhibits a high dielectric constant of 80.5, low dielectric loss of 6.5×10-4 and small temperature coefficient of dielectric constant of -78×10-6 K-1 at 1 MHz due to its close structure and relative high dielectric polarizabilities of Ba2+, La3+, Ti4+ and Nb5+. Ba5LaTi2Nb3O18 might be a suitable candidate of high εr microwave dielectric ceramics.

Key words: Niobate, Perovskite-related structure, Dielectric property

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