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Characterization and Microwave Dielectric Properties of M 2+ Nb 2 O 6 Ceramics
Author(s) -
Pullar Robert C.,
Breeze Jonathan D.,
Alford Neil McN.
Publication year - 2005
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2005.00458.x
Subject(s) - columbite , analytical chemistry (journal) , ceramic , microstructure , materials science , dielectric , permittivity , mineralogy , temperature coefficient , sintering , pyrochlore , barium oxide , oxide , phase (matter) , chemistry , metallurgy , composite material , optoelectronics , organic chemistry , chromatography
This paper details the investigation of the quality factor ( Q ), dielectric permittivity (ɛ r ) and temperature coefficient of resonant frequency (τ f ) of the TE 01δ mode of the columbite binary niobate ceramics, with the formula MNb 2 O 6 where M= 2+ cation, in relation to their degree of sintering, microstructure and phase composition. The ceramics were made from a mixed oxide preparative route and fired over a range of temperatures from 800° to 1400°C, and most formed the columbite structure. A comprehensive study was made of the niobates containing the transition metal cations M=Mn 2+ , Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ , and the group II metal cations M=Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ . All columbite niobates were found to have ɛ r between 17 and 22 and negative τ f values between –45 and –76 ppm/°C, and ZnNb 2 O 6 , MgNb 2 O 6 , CaNb 2 O 6 , and CoNb 2 O 6 had high Q f values of 84 500, 79 600, 49 600, and 41 700 GHz, respectively. The Q f of MgNb 2 O 6 was found to rise to over 95 000 GHz when heated at 1300°C for 50 h.