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https://doi.org/10.3938/NPSM.67.1426
Effect of the Electrode Material and Process on the Electrical Properies in BaTiO$_3$
New Phys.: Sae Mulli 2017; 67: 1426~1431
Published online December 29, 2017;  https://doi.org/10.3938/NPSM.67.1426
© 2017 New Physics: Sae Mulli.

Gwangsu KIM, Sumin LEE, Yongjei LEE*

Department of Physics, Kunsan National University, Gunsan 54150, Korea
Correspondence to: tricon.lee@kunsan.ac.kr
Received September 29, 2017; Revised October 20, 2017; Accepted October 20, 2017.
cc This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
In the positive temperature coefficient (PTC) BaTiO$_3$ ceramics, the change in the electrical resistance and change factors according to the material and the process used for the electrode were investigated. The resistance change was proposed to be due to oxygen vacancies. The device resistance with a low-temperature liquid electrode (Ga-In, Ga-Al, In and Ga) is shown to be determined by the surface state of BaTiO$_3$, rather than by the work function of the electrode. The contributions of the resistance to the electrode diffusion and contact area were determined by using the heating temperature. The formation of oxygen vacancies due to the reduction process resulted in a decrease in the device resistance of 100 times or more and a decrease in the PTC characteristics, which had the greatest influence among the resistance change factors. This change in resistance by reduction can be explained as forming free electrons from oxygen vacancies, causing a resistance decrease and a lowering the potential barrier by compensating for the acceptor of the grain boundaries at temperatures above $T_C$.
PACS numbers: 81.15.Pq, 73.61.-r
Keywords: Positive temperature coefficient (PTC), BaTiO$_3$, Electrode, Oxygen vacancy


April 2018, 68 (4)
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