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Microstructural and electrical properties of varistors prepared from coated ZnO nanopowders

Shojaee, S. A ; Sharif University of Technology | 2010

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  1. Type of Document: Article
  2. DOI: 10.1007/s10854-009-9959-3
  3. Publisher: 2010
  4. Abstract:
  5. This paper describes a solution-based technique for fabrication of varistor grade composite nanopowders. The method consists of coating major varistor dopants on the surface of the ZnO nanoparticles. As a result, a homogenous mixture of dopants and ZnO nanoparticles will be achieved. TEM results indicated that a composite layer of dopants with the average particle size of 9 nm on the surface of ZnO nanoparticles has been successfully prepared. Sintering of the coated powders was performed in temperatures as low as 850 °C and final specimens with average particle size of 900 nm and density of 98.5% were achieved. In comparison to conventional mixing, varistors prepared from coated nanopowders exhibited superior electrical properties and microstructure homogeneity. The improvement of electrical properties can be attributed to small grain size, homogenous distribution of dopants and elimination of large Bi-Pockets. In addition, the processing route of schottky barrier formation is quite different from what is generally considered as the method of barrier formation in ZnO grain boundaries
  6. Keywords:
  7. Average particle size ; Barrier formation ; Coated powders ; Composite layer ; Electrical properties and microstructure ; Electrical property ; Homogenous mixtures ; Micro-structural ; Nano powders ; Processing Route ; Schottky barriers ; Small grain size ; TEM ; ZnO ; ZnO nanoparticles ; Grain boundaries ; Grain size and shape ; Nanoparticles ; Nanostructured materials ; Schottky barrier diodes ; Sintering ; Varistors ; Zinc oxide ; Electric properties
  8. Source: Journal of Materials Science: Materials in Electronics ; Volume 21, Issue 6 , June , 2010 , Pages 571-577 ; 09574522 (ISSN)
  9. URL: http://link.springer.com/article/10.1007%2Fs10854-009-9959-3