Effects of lead oxide on zinc oxide varistor ceramics

Date

3-2006

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Marvin U. Herrera

Abstract

The effects of lead oxide (PbO) on the physical, structural, thermal and electrical characteristics of zinc oxide varistor ceramics were surveyed in this study. PbO was added to two ZnO systems in varying concentrations of 1mol%, 5mol% and 10mol%. The first system was made up of only ZnO while the second system is the ZnO-Bi2O3- Sb2O3 system. Results show that the addition of PbO decreases the systems' melting points. Due to the lowered melting point, the grain boundaries fuse together during the sintering process. This leads to increased grain size of the samples. Doping with a small amount of PbO to the systems causes the grains to become disordered. This results to an increase in porosity. However, as more PbO is added, the grains become more fused together, producing less grain boundaries per unit area. This leads to a decrease in the porosity of the samples. In the ZnO system, adding 5mol% PbO to the ceramic creates the necessary grain boundaries for ZnO to become a varistor. The dopant also increases the conductivity of ZnO and the upturn region of the ZnO-PbO varistors. PbO had a minimal effect on the nonlinear coefficient and breakdown voltage of the device. In the ZnO-Bi203-Sb203 system, doping with PbO decreased the conductivity of the upturn regions of the samples. It decreased the nonlinear region of the varistors. It also increased the nonlinear coefficient and breakdown voltage of the device.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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