Showing papers by "Dragan Uskoković published in 1990"
15 citations
TL;DR: In this paper, the structure of ZnO varistors prepared by different chemical methods was studied by the electronic paramagnetic resonance (EPR) method, and the presence of Mn2+ ions in both ZnOs and electroconductive phase was used as a sensitive "probe" for the analyses of structural changes which occur during sintering.
Abstract: The structure of ZnO varistors prepared by different chemical methods was studied by the electronic paramagnetic resonance (EPR) method. The presence of Mn2+ ions in both ZnO lattice and electroconductive phase was used as a sensitive “probe” for the analyses of structural changes which occur during sintering of ZnO varistors. Potential mechanisms which can contribute to the formation of resonant lines were considered. The concentration of paramagnetic centres was quantitatively analysed. The variation of EPR signals of Mn2+ ions in ZnO phase was registered as a function of the chemical methods used for the preparation of powders only when samples were sintered at lower temperatures and non-linear characteristics of varistor ceramics had not yet been reached. At higher sintering temperatures EPR signals of Mn2+ ions in electroconductive phase differed only in the case of powders obtained by NaOH coprecipitation.
5 citations
TL;DR: In this paper, the changes occurring in the structure of shock-compacted amorphous Ni 78 P 22 powder in the pressure range 50 −150 kbar were studied and the minimum porosity (≈2.5%) was obtained at 70 kbar.
1 citations