Crystal phase analysis of SnO{sub 2}-based varistor ceramic using the Rietveld method

A second addition of l mol% of CoO to a pre calcined SnO{sub 2}-based ceramic doped with 1.0 mol% of CoO, 0.05 mol% of Nb{sub 2}O{sub 5} and 0.05 mol% of Cr{sub 2}O{sub 3} promotes the appearance of a secondary phase, Co{sub 2}SnO{sub 4}, besides the SnO{sub 2} cassiterite phase, when the ceramic wa...

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Bibliographic Details
Published in:Materials characterization 2006-09, Vol.57 (3)
Main Authors: Moreira, M.L., Pianaro, S.A., Andrade, A.V.C., Zara, A.J.
Format: Article
Language:English
Subjects:
CERAMICS
CHROMATES
CHROMIUM OXIDES
COBALT IONS
CRYSTALS
DOPED MATERIALS
MATERIALS SCIENCE
MICROSTRUCTURE
NIOBATES
NIOBIUM OXIDES
PHASE STUDIES
SCANNING ELECTRON MICROSCOPY
TIN OXIDES
X RADIATION
X-RAY DIFFRACTION
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Summary:A second addition of l mol% of CoO to a pre calcined SnO{sub 2}-based ceramic doped with 1.0 mol% of CoO, 0.05 mol% of Nb{sub 2}O{sub 5} and 0.05 mol% of Cr{sub 2}O{sub 3} promotes the appearance of a secondary phase, Co{sub 2}SnO{sub 4}, besides the SnO{sub 2} cassiterite phase, when the ceramic was sintered at 1350 deg. C/2 h. This was observed using X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray techniques. Rietveld refinement was carried out to quantify the phases present in the ceramic system. The results of the quantitative analysis were 97 wt.% SnO{sub 2} and 3 wt.% Co{sub 2}SnO{sub 4}. The microstructural analysis showed that a certain amount of cobalt ion remains into cassiterite grains.
ISSN:1044-5803
1873-4189
DOI:10.1016/j.matchar.2006.01.012