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Vol.52, No.12, 1017 ~ 1024, 2014
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| Title |
| Defects and Electrical Properties of ZnO-Co3O4-Cr2O3 with Sintering Temperature |
| 홍연우 Youn Woo Hong , 김유비 You Bi Kim , 이영진 Young Jin Lee , 김세기 Sei Ki Kim , 백종우 Jong Hoo Paik , 조만호 Man Ho Jo |
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| Abstract |
| The defects and origin of the good varistor properties in the ZnO-Co3O4-Cr2O3 system were investigated by admittance spectroscopy, I-V characteristics, and impedance and modulus spectroscopy. Two kinds of defects were detected, but (0.27 eV) was identified as a major donor level by admittance spectroscopy. The ZnO grain resistivity of ~0.4 Ωcm was calculated but somewhat increased with sintering temperature. J-E characteristics with varistor behavior was seen in this system while the nonlinear coefficient α changed from 9 to 92 with sintering temperature. The single potential barrier of 0.64-1.01 eV at the grain boundary region was confirmed by impedance and modulus spectroscopy. The origin of a good varistor behavior in ZnO-Co3O4-Cr2O3 would be due to the formation and stabilization of a double Schottky barrier by the redox reaction of Co ions and the existence of small Cr ions in the grain boundaries. |
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| Key Words |
| electronic materials, ZnO varistor, sintering, defects, grain boundary |
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