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The effect of TiO 2 on the microstructural and electrical properties of low voltage varistor based on (Sn,Ti)O 2 ceramics
Author(s) -
Leite D. R.,
Cilense M.,
Orlandi M. O.,
Bueno P. R.,
Longo E.,
Varela J. A.
Publication year - 2010
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200925304
Subject(s) - varistor , materials science , dopant , scanning electron microscope , grain boundary , breakdown voltage , ceramic , schottky barrier , analytical chemistry (journal) , doping , oxide , composite material , microstructure , mineralogy , voltage , optoelectronics , metallurgy , electrical engineering , chemistry , diode , chromatography , engineering
SnO 2 ·CoO·Nb 2 O 5 ceramics doped with TiO 2 have been prepared by a conventional oxide method which focuses its application on low voltage varistors. The dopant was added in 0.5 and 1.0% molar concentrations, and the samples were investigated by X‐ray diffraction, scanning electron microscopy, current vs . voltage, and impedance measurements. The electron microscopy results showed an increase in the mean grain size of ceramics with the addition of TiO 2 , which is related to the effect of the dopant on the matrix. The electrical characterization showed that the addition of TiO 2 in 1 mol% provides a system with a good nonlinear coefficient (8.7) and a breakdown electrical field of 617 V/cm. These results indicate that this composition can be applied as a low voltage varistor. The impedance data showed that the voltage barrier at the grain boundary is a back‐to‐back Schottky‐type, and it was demonstrated that the addition of TiO 2 does not significantly modify the barrier.