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Title: High Schottky barrier at grain boundaries observed in Na{sub 1/2}Sm{sub 1/2}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics

Graphical abstract: - Highlights: • NSCTO exhibits a high ε′ of 7.0–8.4 × 10{sup 3} and low tan δ of 0.030–0.041. • NSCTO exhibits a high E{sub b} of ∼2208 V cm{sup −1} and large α of 15.6. • Giant ε′ response is attributed to the electrically heterogeneous microstructure. • High Φ{sub b} values at grain boundaries are found to be 0.925–0.964 eV. • Formation of a potential barrier at grain boundaries is caused by Schottky effect. - Abstract: The dielectric properties and nonlinear current–voltage characteristics of Na{sub 1/2}Sm{sub 1/2}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics prepared by a conventional solid state reaction method were investigated. Na{sub 1/2}Sm{sub 1/2}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics exhibited a high dielectric permittivity of 7.0–8.4 × 10{sup 3} and low loss tangent (tan δ∼0.030–0.041). Non-Ohmic properties with a high breakdown voltage of ∼2208 V cm{sup −1} and large nonlinear coefficient of 15.6 were observed in Na{sub 1/2}Sm{sub 1/2}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics. Using complex impedance analysis, Na{sub 1/2}Sm{sub 1/2}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics were shown to be electrically heterogeneous consisting of semiconducting grains and insulating grain boundaries. Giant dielectric properties were described based on the electrically heterogeneous microstructure. X-ray photoelectron spectroscopy analysis suggested that the semiconductive naturemore » of grains may be related to the presence of Cu{sup +} and Ti{sup 3+}. The formation of an electrostatic potential barrier at the grain boundaries of Na{sub 1/2}Sm{sub 1/2}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics was suggested to be caused by the Schottky effect. Interestingly, high electrostatic potential barriers at grain boundaries in Na{sub 1/2}Sm{sub 1/2}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics were calculated and found to be 0.925–0.964 eV.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand)
  2. Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand)
  3. (INRC), Khon Kaen University, Khon Kaen 40002 (Thailand)
  4. National Metal and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani 12120 (Thailand)
  5. School of Physics, Institute of Science, Suranaree University, Nakhon Ratchasima 30000 (Thailand)
Publication Date:
OSTI Identifier:
22285138
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 48; Journal Issue: 10; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CERAMICS; COPPER IONS; DIELECTRIC MATERIALS; GRAIN BOUNDARIES; PERMITTIVITY; SCHOTTKY EFFECT; TITANIUM IONS; X-RAY PHOTOELECTRON SPECTROSCOPY