Lanthanum Oxide Doping for Superior Breakdown Voltage in Praseodymium-Based SnO ₂ Varistors for High-Voltage Protection

Abstract

In this study, the effect lanthanum oxide (La<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>) doping has on the electrical and physical properties of tin oxide $\left(\mathrm{SnO}_{2}\right)$-based praseodymium oxide $\left(\mathrm{Pr}_{2} \mathrm{O}_{3}\right)$-varistors is investigated. Varistor samples with varying La<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> content were fabricated via the solid-state reaction method and characterized for their microstructure, electrical performance, and thermal stability. The results indicate that lanthanum oxide doping is critical for controlling grain size, grain morphology, and the amount of barrier layer produced at grain boundaries, which in turn affects varistor features such as breakdown voltage and the nonlinear coefficient. The lanthanum doping also affected the sintering behaviour and thermal stability of the samples. The findings provide valuable insight into the mechanisms by which L<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> alters the grain-boundary chemistry and electronic transport in $\mathrm{SnO}_{2}-\mathrm{Pr}_{2} \mathrm{O}_{3}$ systems, offering a practical pathway to engineer varistors with superior surge protection performance.