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Dielectric relaxation and giant dielectric constant of Nb‐doped CaCu 3 Ti 4 O 12 ceramics under dc bias voltage
Author(s) -
Liu Peng,
He Ying,
Zhou Jianping,
Mu Chunhong,
Zhang Huaiwu
Publication year - 2009
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200824277
Subject(s) - dielectric , materials science , ceramic , analytical chemistry (journal) , doping , grain boundary , biasing , relaxation (psychology) , capacitance , condensed matter physics , grain size , high κ dielectric , mineralogy , composite material , voltage , microstructure , electrical engineering , electrode , chemistry , optoelectronics , psychology , social psychology , physics , engineering , chromatography
CaCu 3 Ti 4– x Nb x O 12 ( x = 0, 0.01, 0.08, 0.2) ceramics were fabricated by a conventional solid‐state reaction method. The ceramics showed the body‐centered cubic structure without any foreign phases and the grain size decreases with Nb doping. Two Debye‐type relaxations were observed for the Nb‐doped samples at low frequency and high frequency, respectively. The complex electric modulus analysis revealed that the surface layer, grains and grain boundaries contributed to the dielectric constant. The low‐frequency dielectric constant relative to the surface layer decreased to a minimum and then increased with the dc bias voltage at 100 Hz, which were well explained in terms of a model containing two metal oxide semiconductors in series, confirming the surface layer in the ceramics. The shift voltage V B corresponding to the minimal capacitance increased with increase of the composition x . (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)