Improved dielectric properties of the CaCu sub(3)Ti sub(4)O sub(12) composites using BaTiO sub(3)-coated powder as precursor

A high dielectric loss and a large leakage current of CaCu sub(3)Ti sub(4)O sub(12) (CCTO) ceramics could be greatly suppressed by using BaTiO sub(3) (BTO)-coated CCTO powder as precursor. BTO-coated CCTO precursors with 5, 10, and 15 mol% BTO relative to CCTO were prepared by a sol-gel process and...

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Bibliographic Details
Published in:Journal of alloys and compounds 2014-10, Vol.610, p.594-599
Main Authors: Kim, Hui Eun, Choi, Soon-Mi, Hong, Youn-Woo, Yoo, Sang-Im
Format: Article
Language:English
Subjects:
Barium titanates
BOUNDARIES
CERAMICS
COATINGS
COPPER OXIDE
DIELECTRIC CONSTANT
Dielectric loss
ELECTRICAL PROPERTIES
Grain boundaries
INSULATION (ELECTRICAL)
Leakage current
PHASES
POWDERS
Precursors
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Summary:A high dielectric loss and a large leakage current of CaCu sub(3)Ti sub(4)O sub(12) (CCTO) ceramics could be greatly suppressed by using BaTiO sub(3) (BTO)-coated CCTO powder as precursor. BTO-coated CCTO precursors with 5, 10, and 15 mol% BTO relative to CCTO were prepared by a sol-gel process and a subsequent calcination at 850 [degrees]C for 3 h in pure oxygen gas atmosphere. All samples were sintered at 1060 [degrees]C for 12 h in air. Compared with pure CCTO sample of [varepsilon] sub(r) ~ 52, 000 and tan delta ~ 0.38 at 100 kHz, all CCTO composite samples exhibited significantly reduced dielectric losses and leakage currents. Among all CCTO composite samples, the sample using 5 mol% BTO-coated CCTO powder exhibited the most improved properties of the dielectric loss (tan delta ~ 0.04 up to 100 kHz) and the leakage current (less than 1% up to DC field of ~1 kV/cm) although a large suppression in its dielectric constant ([varepsilon] sub(r)~6000 up to 100 kHz) was unavoidable. This improvement is mainly attributed to a relatively uniform distribution of the second phases such as Ba sub(4)Ti sub(12)O sub(27) and CaTiO sub(3) at the CCTO grain boundary, which were formed by the chemical reaction between CCTO and BTO during the sintering process.
ISSN:0925-8388
DOI:10.1016/j.jallcom.2014.04.215