| A novel method for improving the microstructure and electrical properties of Pr6O11-based ZnO varistors |
Salem A. S. Qaid1
, M. A. A. Issa1, A. M. Hassib1, Bandar Ali Al-Asbahi1, E. M. Abuassaj2, Abdullah Ahmed Ali Ahmed3 |
1Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
2Department of Physics, North Maharashtra University, Jalgaon 425001, India
3Center for Hybrid Nanostructures (CHyN) and Fachbereich Physik, Universität Hamburg, 20146 Hamburg, Germany |
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Received: December 10, 2021; Revised: May 1, 2022 Accepted: May 31, 2022. Published online: July 18, 2022. |
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| ABSTRACT |
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The effects of different synthesis routes and sintering temperatures on the microstructures and electrical properties of ceramic varistors (composed of ZnO doped with Pr6O11, Co3O4, Cr2O3, and Nd2O3) were investigated. Two types of samples were prepared according to the milling approach (single-mill or double-mill). Remilling the calcined powder material reduced the required sintering temperature by 100 °C, improved the microstructure of the ceramic, and enhanced the nonlinear properties of the varistor. Though the different sintering temperatures and average grain sizes, both types were reach ≈ 98% of the theoretical density. The highest nonlinear coefficient value was ≈ 26.5, obtained from the first sample of the double-mill batch. As the sintering temperature increased, the nonlinearity diminished rapidly in the case of single-mill samples compared to double-mill ones. Similar behavior was noted for the varistor (breakdown) voltage. The thermionic emission behavior at the pre-breakdown region and the conduction mechanism through Schottky barriers were applied to fi nd further electrical parameters. |
| Key words:
ZnO varistors · Ceramic semiconductors · Sintering temperature · Non-linear coefficient |
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