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The Lowered Dielectric Loss and Grain‐Boundary Effects in La ‐doped Y 2/3 Cu 3 Ti 4 O 12 Ceramics
Author(s) -
Liang Pengfei,
Chao Xiaolian,
Wang Fang,
Liu Zhanqing,
Yang Zupei
Publication year - 2013
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.12644
Subject(s) - grain boundary , dielectric , relaxation (psychology) , materials science , analytical chemistry (journal) , dielectric loss , electrical resistivity and conductivity , grain size , ceramic , doping , conductivity , mineralogy , chemistry , composite material , microstructure , electrical engineering , psychology , social psychology , optoelectronics , chromatography , engineering
The effects of La concentration on the electrical conductivity and electric modulus of Y 2/3− x La x Cu 3 Ti 4 O 12 ceramics (0.00 ≦ x ≦ 0.20) were investigated in detail. Proper amount of La substitution in Y 2/3− x La x Cu 3 Ti 4 O 12 ceramics made the dielectric loss decreased. When x = 0.10, Y 2/3−0.10 La 0.10 Cu 3 Ti 4 O 12 ceramics exhibited the highest grain‐boundary resistance (0.893 MΩ) and the lowest dielectric loss (about 0.025 at 1 kHz), meanwhile the samples exhibited a relatively high dielectric constant above 6000 over a wide frequency range from 40 Hz to 1 MHz. The decreased dielectric loss was attributed to the enhanced grain‐boundary resistance. With the increase in La concentration, the dielectric relaxation behaviors correlated with the grain‐boundary effects were significantly enhanced. By La doping, the activation energies for the conduction in grain boundaries were slightly depressed, and the activation energies for the relaxation process in grain boundaries were slightly changed. Based on the activation values, it can be concluded that the doubly ionized oxygen vacancies V O ∙ ∙had substantial contribution to the conduction and relaxation behaviors in grain boundaries.