Silica Additions and the Performance of PTC Thermistors

Abstract:

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A series of PTC thermistors, based on BaTiO3, doped with Ca, Mn and Y, were prepared with additions of SiO2 at levels of 0, 1, 2 and 3 at. %. The effect of the SiO2 additions and cooling rate on microstructural development and bulk performance were characterised using a combination of SEM, EBSD, and R-T experiments. It was found that the addition of SiO2 increased grain size marginally, and decreased sample density by reducing the amount of grain-grain contact. The addition of SiO2 also modified the distribution of grain boundary types by systematically decreasing the proportion of low-Σ grain boundaries within the microstructure. Electrical behaviour was modified by adding SiO2 or increasing the sample cooling rates; in both cases there was an increase in ρ25 and a decrease in ρmax, with ρmax also being displaced to higher temperatures.

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Periodical:

Edited by:

P. VINCENZINI

Pages:

2362-2370

DOI:

10.4028/www.scientific.net/AST.45.2362

Citation:

C. Leach et al., "Silica Additions and the Performance of PTC Thermistors", Advances in Science and Technology, Vol. 45, pp. 2362-2370, 2006

Online since:

October 2006

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$35.00

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