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
- Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand)
- Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand)
- National Metal and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani 12120 (Thailand)
- School of Physics, Institute of Science, Suranaree University, Nakhon Ratchasima 30000 (Thailand)
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 nature 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.
- OSTI ID:
- 22285138
- Journal Information:
- Materials Research Bulletin, Vol. 48, 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); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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