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Title: Giant dielectric response and low dielectric loss in Al{sub 2}O{sub 3} grafted CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

This study sheds light on the effect of alumina on dielectric constant and dielectric loss of novel CaCu{sub 3}Ti{sub 4}O{sub 12} composite ceramics. Alumina, at several concentrations, was deposited on the surface of CaCu{sub 3}Ti{sub 4}O{sub 12} particles via sol-gel technique. The dielectric constant significantly increased for all frequencies and the dielectric loss substantially decreased for low and intermediate frequencies. These observations were attributed to the change in characteristics of grains and grain boundaries. It was found that the insulating properties of the grain boundaries are improved following the addition of Al{sub 2}O{sub 3}. The relative density of CaCu{sub 3}Ti{sub 4}O{sub 12}/Al{sub 2}O{sub 3} composite ceramics decreased compared to the pure CaCu{sub 3}Ti{sub 4}O{sub 12} and the grain size was greatly changed with the alumina content affecting the dielectric properties. With the addition of alumina into CaCu{sub 3}Ti{sub 4}O{sub 12}, tighter interfaces formed. The 6%- and 10%-alumina ceramics showed the minimum dielectric loss and the maximum dielectric constant, respectively. Both the dielectric constant and loss tangent decreased in the 20%-alumina ceramic due to the formation of CuO secondary phase. It was revealed that Al serves as an electron acceptor decreasing the electron concentration, if Al{sup 3+} ions substitute for Ti{supmore » 4+} ions, and as an electron donor increasing the electron concentration, if Al{sup 3+} ions substitute for Ca{sup 2+} ions. We established a processing-microstructure-properties paradigm which opens new avenues for novel applications of CaCu{sub 3}Ti{sub 4}O{sub 12}/Al{sub 2}O{sub 3} composite ceramics.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ; ; ; ;  [4]
  1. School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)
  2. (ZONA), Johannes Kepler University, Altenberger Straße 69, 4040 Linz (Austria)
  3. Intel Corporation, IMO-RA, RA2, Hillsboro, Oregon 97124 (United States)
  4. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)
Publication Date:
OSTI Identifier:
22413211
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 9; 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; ALUMINIUM IONS; ALUMINIUM OXIDES; BINDING ENERGY; CALCIUM COMPOUNDS; CALCIUM IONS; CERAMICS; COMPOSITE MATERIALS; CONCENTRATION RATIO; COPPER COMPOUNDS; COPPER OXIDES; DIELECTRIC MATERIALS; GRAIN BOUNDARIES; GRAIN SIZE; INTERFACES; PERMITTIVITY; SOL-GEL PROCESS; SURFACES; TITANATES; TITANIUM IONS; VALENCE