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Title: Room temperature magnetic and dielectric properties of cobalt doped CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

CaCu{sub 3}Ti{sub 4−x}Co{sub x}O{sub 12} (x = 0, 0.2, 0.4) ceramics were prepared by a conventional solid state reaction, and the effects of cobalt doping on the room temperature magnetic and dielectric properties were investigated. Both X-ray diffraction and energy dispersive X-ray spectroscopy confirmed the presence of Cu and Co rich phase at grain boundaries of Co-doped ceramics. Scanning electron microscopy micrographs of Co-doped samples showed a striking change from regular polyhedral particle type in pure CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) to sheet-like grains with certain growth orientation. Undoped CaCu{sub 3}Ti{sub 4}O{sub 12} is well known for its colossal dielectric constant in a broad temperature and frequency range. The dielectric constant value was slightly changed by 5 at. % and 10 at. % Co doping, whereas the second relaxation process was clearly separated in low frequency region at room temperature. A multirelaxation mechanism was proposed to be the origin of the colossal dielectric constant. In addition, the permeability spectra measurements indicated Co-doped CCTO with good magnetic properties, showing the initial permeability (μ′) as high as 5.5 and low magnetic loss (μ″ < 0.2) below 3 MHz. And the interesting ferromagnetic superexchange coupling in Co-doped CaCu{sub 3}Ti{sub 4}O{sub 12} was discussed.
Authors:
; ;  [1] ;  [2]
  1. School of Energy Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731 (China)
  2. School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China)
Publication Date:
OSTI Identifier:
22409977
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CALCIUM COMPOUNDS; CERAMICS; COBALT; CONCENTRATION RATIO; COPPER COMPOUNDS; DOPED MATERIALS; FREQUENCY DEPENDENCE; GRAIN BOUNDARIES; MAGNETIC PROPERTIES; MHZ RANGE; PERMITTIVITY; RELAXATION LOSSES; SCANNING ELECTRON MICROSCOPY; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0273-0400 K; TITANATES; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY