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Structure, Microwave Dielectric Properties, and Low‐Temperature Sintering of Acceptor/Donor Codoped Li 2 Ti 1− x (Al 0.5 Nb 0.5 ) x O 3 Ceramics
Author(s) -
Zhang Tianwen,
Zuo Ruzhong,
Zhang Jian
Publication year - 2016
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/jace.14055
Subject(s) - materials science , sintering , analytical chemistry (journal) , dielectric , ceramic , phase (matter) , scanning electron microscope , acceptor , microstructure , atmospheric temperature range , mineralogy , metallurgy , composite material , chemistry , physics , optoelectronics , organic chemistry , chromatography , meteorology , condensed matter physics
The structure, microwave dielectric properties, and low‐temperature sintering behavior of acceptor/donor codoped Li 2 TiO 3 ceramics [Li 2 Ti 1− x (Al 0.5 Nb 0.5 ) x O 3 , x = 0–0.3] were investigated systematically. The x‐ray diffraction confirmed that a single‐phase solid solution remained within 0 < x ≤ 0.2 and secondary phases started to appear as x > 0.2, accompanied by an order–disorder phase transition in the whole range. Scanning electron microscopy observation indicated that the complex substitution of Al 3+ and Nb 5+ produced a significant effect on the microstructural morphology. Both microcrack healing and grain growth contributed to the obviously enhanced Q × f values. By comparison, the decrease of ε r and τ f values was ascribed to the ionic polarizability and the cell volume, respectively. Excellent microwave dielectric properties of ε r ~ 21.2, Q × f ~ 181 800 GHz and τ f ~ 12.8 ppm/°C were achieved in the x = 0.15 sample when sintered at 1150°C. After 1.5 mol% BaCu(B 2 O 5 ) additive was introduced, it could be well sintered at 950°C and exhibited good microwave dielectric properties of ε r ~ 20.4, Q × f ~ 53 290 GHz and τ f ~ 3.6 ppm/°C as well. The cofiring test of the low‐sintering sample with Ag powder proved its good chemical stability during high temperature, which enables it to be a promising middle‐permittivity candidate material for the applications of low‐temperature cofired ceramics.