Coalescence growth mechanism of inserted tin dioxide belts in polycrystalline SnO2-based ceramics

Abstract

SnO 2-based varistors have been considered promising technological devices. However their practical application is usually stated as limited to high voltage circuits based on the high breakdown electric field exhibited by these ceramics. Recently, authors have shown that the insertion of one-dimensional (1D) SnO 2 belts allows overcoming this limitation. In this work, we present a detailed study of the growth mechanism of the belts inside varistors using electron microscopy techniques. We were able to show that mass transport has an intrinsic dependence on the sintering time and requires similar crystalline structure between the belts and the matrix. Dual beam and high-resolution transmission electron microscopy techniques permitted determining that 3D growth of belts occurs by coalescence.

The Influence of Holding Time on the Microstructure Evolution of Mg–10Zn–6.8Gd–4Y Alloy during Semi-Solid Isothermal Heat Treatment

“…The prerequisite for coalescence is that the sizes of two adjacent grains are different, so that the larger grains absorb the smaller ones when the grain boundary is dissolving. Likewise, if there is a low crystallographic disorientation between the adjacent grains, this can also trigger coalescence [19,20]. The systems that have high values of the solid-liquid interfacial energy coarsen by Ostwald ripening.…”