Structural ordering and dielectric properties of Ba3CaNb2O9-based microwave ceramics

• Published in: Ceramics international Vol. 42; no. 16; pp. 18087 - 18093
• Main Authors: Rodrigues, J.E.F.S., Castro, P.J., Pizani, P.S., Correr, W.R., Hernandes, A.C.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2016
• Subjects: 1:2 ordered perovskite; Ba(Ca1/3Nb2/3)O3; Cation ordering; Dielectric resonator; Microwave dielectric properties; Cation ordering; Ba(Ca1/3Nb2/3)O3; Dielectric resonator; 1:2 ordered perovskite; Microwave dielectric properties
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2016.08.113

Ba3CaNb2O9 is a 1:2 ordered perovskite which presents a trigonal cell within the D3d3 space 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 = 15,752GHz; τf ~ 278ppm°C−1.