Microstructural and compositional aspects of ZnO-based varistor ceramics prepared by direct mixing of the constituent phases and high-energy milling
Abstract
ZnO-based varistor samples were prepared by the direct mixing of the constituent phases (DMCP) and sintering at 1100 degrees C for 2 h. The influence of the starting powder mixture's composition - the amounts of the pre-reacted varistor compounds and their composition - and its preparation, either with or without mechano-chemical activation (MCA), on the microstructure, phase composition and electrical characteristics of the varistor samples was studied. It showed that MCA improved the density and microstructural homogeneity of the varistor samples. MCA strongly affected the grain growth: it enhanced the nucleation of inversion boundaries (IBs) in the ZnO grains and the IBs-induced grain-growth mechanism resulted in uniform grain growth and hence a microstructure with smaller ZnO grains and a narrower grain size distribution. The final phase composition of the samples prepared by the DMCP method mainly depended on the presence of varistor dopants that can prevent the formation of the p...yrochlore phase, especially Cr2O3, while MCA can affect it mostly by providing a homogeneous distribution of those dopants. The DMCP varistor samples prepared with MCA had much better Current-voltage characteristics than the samples of the same composition prepared from unactivated powders.
Keywords:
varistors / microstructure-final / high-energy milling / electrical propertiesSource:
Ceramics International, 2008, 34, 6, 1495-1502Publisher:
- Elsevier Sci Ltd, Oxford
DOI: 10.1016/j.ceramint.2007.04.003
ISSN: 0272-8842
WoS: 000257538200023
Scopus: 2-s2.0-44649113992
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Institution/Community
Institut za multidisciplinarna istraživanjaTY - JOUR AU - Bernik, Slavko AU - Branković, Goran AU - Rustja, S. AU - Žunić, Milan AU - Podlogar, Matejka AU - Branković, Zorica PY - 2008 UR - http://rimsi.imsi.bg.ac.rs/handle/123456789/245 AB - ZnO-based varistor samples were prepared by the direct mixing of the constituent phases (DMCP) and sintering at 1100 degrees C for 2 h. The influence of the starting powder mixture's composition - the amounts of the pre-reacted varistor compounds and their composition - and its preparation, either with or without mechano-chemical activation (MCA), on the microstructure, phase composition and electrical characteristics of the varistor samples was studied. It showed that MCA improved the density and microstructural homogeneity of the varistor samples. MCA strongly affected the grain growth: it enhanced the nucleation of inversion boundaries (IBs) in the ZnO grains and the IBs-induced grain-growth mechanism resulted in uniform grain growth and hence a microstructure with smaller ZnO grains and a narrower grain size distribution. The final phase composition of the samples prepared by the DMCP method mainly depended on the presence of varistor dopants that can prevent the formation of the pyrochlore phase, especially Cr2O3, while MCA can affect it mostly by providing a homogeneous distribution of those dopants. The DMCP varistor samples prepared with MCA had much better Current-voltage characteristics than the samples of the same composition prepared from unactivated powders. PB - Elsevier Sci Ltd, Oxford T2 - Ceramics International T1 - Microstructural and compositional aspects of ZnO-based varistor ceramics prepared by direct mixing of the constituent phases and high-energy milling EP - 1502 IS - 6 SP - 1495 VL - 34 DO - 10.1016/j.ceramint.2007.04.003 ER -
@article{ author = "Bernik, Slavko and Branković, Goran and Rustja, S. and Žunić, Milan and Podlogar, Matejka and Branković, Zorica", year = "2008", abstract = "ZnO-based varistor samples were prepared by the direct mixing of the constituent phases (DMCP) and sintering at 1100 degrees C for 2 h. The influence of the starting powder mixture's composition - the amounts of the pre-reacted varistor compounds and their composition - and its preparation, either with or without mechano-chemical activation (MCA), on the microstructure, phase composition and electrical characteristics of the varistor samples was studied. It showed that MCA improved the density and microstructural homogeneity of the varistor samples. MCA strongly affected the grain growth: it enhanced the nucleation of inversion boundaries (IBs) in the ZnO grains and the IBs-induced grain-growth mechanism resulted in uniform grain growth and hence a microstructure with smaller ZnO grains and a narrower grain size distribution. The final phase composition of the samples prepared by the DMCP method mainly depended on the presence of varistor dopants that can prevent the formation of the pyrochlore phase, especially Cr2O3, while MCA can affect it mostly by providing a homogeneous distribution of those dopants. The DMCP varistor samples prepared with MCA had much better Current-voltage characteristics than the samples of the same composition prepared from unactivated powders.", publisher = "Elsevier Sci Ltd, Oxford", journal = "Ceramics International", title = "Microstructural and compositional aspects of ZnO-based varistor ceramics prepared by direct mixing of the constituent phases and high-energy milling", pages = "1502-1495", number = "6", volume = "34", doi = "10.1016/j.ceramint.2007.04.003" }
Bernik, S., Branković, G., Rustja, S., Žunić, M., Podlogar, M.,& Branković, Z.. (2008). Microstructural and compositional aspects of ZnO-based varistor ceramics prepared by direct mixing of the constituent phases and high-energy milling. in Ceramics International Elsevier Sci Ltd, Oxford., 34(6), 1495-1502. https://doi.org/10.1016/j.ceramint.2007.04.003
Bernik S, Branković G, Rustja S, Žunić M, Podlogar M, Branković Z. Microstructural and compositional aspects of ZnO-based varistor ceramics prepared by direct mixing of the constituent phases and high-energy milling. in Ceramics International. 2008;34(6):1495-1502. doi:10.1016/j.ceramint.2007.04.003 .
Bernik, Slavko, Branković, Goran, Rustja, S., Žunić, Milan, Podlogar, Matejka, Branković, Zorica, "Microstructural and compositional aspects of ZnO-based varistor ceramics prepared by direct mixing of the constituent phases and high-energy milling" in Ceramics International, 34, no. 6 (2008):1495-1502, https://doi.org/10.1016/j.ceramint.2007.04.003 . .