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Physics Research InternationalVolume 2010 2010, Article ID 120672, 9 pages

Research Article

Physics Department, Faculty of Science, King Faisal University, P.O. B 400, Al-Hassa 31982, Saudi Arabia

Physics Department, Faculty of Science, Assiut University, Assiut 71516, Egypt

Received 3 October 2009; Revised 28 December 2009; Accepted 10 February 2010

Academic Editor: Ali Hussain Reshak

Copyright © 2010 A. Sedky and E. El-Suheel. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A comparative study between effects of Mn and Al on the properties of ZnO varistor sintered at 1200 is investigated by XRD, SEM hardness, and I-V measurements. Although both Mn and Al do not influence the well-known peaks related to wurtzite structure of ZnO ceramics, some other unknown peaks could be formed at higher doping content . Also, the shape and size of grains are clearly different for both dopants. Average crystalline diameters, deduced from XRD analysis, are between 42 nm and 62 nm, which are 50 times lower than those obtained from SEM micrographs, while the oxygen vacancies deduced from EDAX analysis, are gradually decreased by doping content for both dopants. Interestingly, the values of breakdown field, nonlinear coefficient and barrier height are found to be higher in Mn samples as compared to Al samples, while the opposite is reported for leakage currents, hardness, and electrical conductivities. The values of are changed from 2.67 V-cm to 41.67 V-cm for Al, and from 1928 V-cm to 6571 V-cm for Mn. The conductivity of Al samples is higher than that of ZnO, and it is nearly 103–105 times the conductivity of Mn samples. These results are discussed in terms of the difference of magnetic moment and valence state between these two additives.

Autor: A. Sedky and E. El-Suheel

Fuente: https://www.hindawi.com/


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