Structural ordering and dielectric properties of Ba3CaNb2O9-based microwave ceramics

1-s2.0-S0272884216314213-main

J.E.F.S. RodriguesP.J. CastroP.S. PizaniW.R. Correr and A.C. Hernandes

Ceramics International Volume 42, Issue 16, December 2016, Pages 18087–18093
http://dx.doi.org/10.1016/j.ceramint.2016.08.113

Ba3CaNb2O9 is a 1:2 ordered perovskite which presents a trigonal cell within the D3d3space group. Dense ceramics of Ba3CaNb2O9 were prepared by the solid-state reaction route, and their microwave dielectric features were evaluated as a function of the sintering time. From Raman spectroscopy, by using group-theory calculations, we were able to recognize the coexistence of the 1:1 and 1:2 ordering types in all samples, in which increasing the sintering time tends to reduce the 1:1 domain, leading to an enhancement of the unloaded quality factor. We concluded that this domain acts as a lattice vibration damping, consequently raising the dielectric loss at microwave frequencies. The best microwave dielectric parameters were determined in ceramics sintered at 1500 °C for 32h: ε′ ~ 43; Qu×fr = 15,752 GHz; τf ~ 278 ppm °C−1.

 

Amanda Murgo
Sobre Amanda Murgo 134 Artigos
Educadora do Laboratório de Difusão Científica (LaDiC) do Grupo Crescimento de Cristais e Materiais Cerâmicos (CCMC/IFSC/USP) no âmbito das ações de Difusão Científica do CDMF. Assessora de Comunicação do CCMC/LaDiC/CDMF desde 2010. Bacharel em Filosofia pela Universidade Federal de São Carlos com estágio no Projeto "História da Ciência e Meio Ambiente - as demandas por energia através da História" (CCMC/IFSC/USP/CDMF) de abril de 2013 a julho de 2014. Atua ministrando cursos de Educação Ambiental em escolas de Rede Básica de Ensino e Educadores com a temática pelo CDMF até os dias atuais.