Importance of oxygen atmosphere to recover the ZnO-based varistors properties

• Published in: Journal of materials science Vol. 41; no. 19; pp. 6221 - 6227
• Main Authors: RAMIREZ, M. A, SIMOES, A. Z, BUENO, P. R, MARQUEZ, M. A, ORLANDI, M. O, VARELA, J. A
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.10.2006; Springer Nature B.V
• Subjects: Applied sciences; Bismuth oxides; Bismuth trioxide; Building materials. Ceramics. Glasses; Ceramic industries; Ceramics; Chemical industry and chemicals; Conductors, resistors (including thermistors, varistors, and photoresistors); Degradation; Electronic devices; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Electrotechnical and electronic ceramics; Exact sciences and technology; Grain boundaries; Heat treatment; Materials science; Nonlinearity; Oxygen; Technical ceramics; Varistors; Zinc oxide; Scanning electron microscopy; Oxygen; Behavior in operation; Electrical properties; Recovery(properties); Experimental study; X ray diffraction; Oxide ceramics; Varistance; Oxidizing atmosphere; Degradation; Zinc oxide; Electroceramics
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-006-0589-3

A methodology to recover the non-ohmic properties of ZnO based varistors after degradation with long and short duration pulses was proposed in this work. The basic idea consists in submitt the degraded ceramics at different temperatures and oxygen flows. Thermal treatment at 900 °C for 2 h with oxygen flow of 15 l/h allowed to obtain better non-linear coefficient (α = 52.5) compared to the standard sample. Rietveld refinement showed that with the thermal treatment, the oxygen species and the β-Bi2O3 phase, lost in the degradation process, are recovered in the grain boundary.