%0 Journal Article
%A Schmidt, Rainer
%A Brinkman, Andrew W.
%T ac hopping admittance in spinel manganate negative temperature coefficient thermistor electroceramics
%D 2008
%@ 0021-8979
%U https://hdl.handle.net/20.500.14352/51556
%X In this work, the ac admittance of a thick film nickel manganate spinel negative temperature coefficient thermistor ceramic system containing a glass phase is investigated. The dominating relaxation process is a grain boundary (GB) effect and has been investigated comprehensively. We present double-logarithmic plots of the specific admittance σ' vs ω   and (σ'/σ_(dc)) vs ω, and specific impedance z vs −z"/ω and [(ρ_(dc)/z')−1] vs ω, in order to characterize GB charge transport. Using the complex admittance notation (σ*), an unusually low Jonscher exponent of frequency ~0.007 was obtained and the GB relaxation displayed close to ideal behavior.
%~