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ISSN : 1225-0562(Print)
ISSN : 2287-7258(Online)
Korean Journal of Materials Research Vol.29 No.10 pp.586-591
DOI : https://doi.org/10.3740/MRSK.2019.29.10.586

Doping Effect of Yb2O3 on Varistor Properties of ZnO-V2O5-MnO2-Nb2O5 Ceramic Semiconductors

Choon-Woo Nahm
Department of Electrical Engineering, Dongeui University, Busan 47340, Republic of Korea
Corresponding author
E-Mail : cwnahm@deu.ac.kr (C.-W. Nahm, Dongeui Univ.)

Abstract

This study describes the doping effect of Yb2O3 on microstructure, electrical and dielectric properties of ZnO-V2O5- MnO2-Nb2O5 (ZVMN) ceramic semiconductors sintered at a temperature as low as 900°C. As the doping content of Yb2O3 increases, the ceramic density slightly increases from 5.50 to 5.54 g/cm3; also, the average ZnO grain size is in the range of 5.3-5.6 μm. The switching voltage increases from 4,874 to 5,494 V/cm when the doping content of Yb2O3 is less than 0.1 mol%, whereas further doping decreases this value. The ZVMN ceramic semiconductors doped with 0.1 mol% Yb2O3 reveal an excellent nonohmic coefficient as high as 70. The donor density of ZnO gain increases in the range of 2.46-7.41×1017 cm−3 with increasing doping content of Yb2O3 and the potential barrier height and surface state density at the grain boundaries exhibits a maximum value (1.25 eV) at 0.1 mol%. The dielectric constant (at 1 kHz) decreases from 592.7 to 501.4 until the doping content of Yb2O3 reaches 0.1 mol%, whereas further doping increases it. The value of tanδ increases from 0.209 to 0.268 with the doping content of Yb2O3.

초록

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