Temperature-induced evolution of novel mixture-phased particles at the tips of SnO2 whiskers

Abstract

A mixture of Sn, In, and Ge powders was thermally evaporated to synthesize SnO2 whiskers. Elevation of the growth temperature from 800 degrees C to 900 degrees C contributed to the generation of mixture-phased particles at the tips of whickers, due to the change of the dominant growth mechanism from base-growth vapor-liquid-solid (VLS) to a tip-growth VLS process. We observed that the particles were comprised of a mixture of tetragonal SnO2, rhomboheclral In2O3, and hexagonal GeO2. The composite materials exhibited stable and reproducible sensing properties with respect to NO2 and CO.