Oxide nanopowders from the low-temperature processing of metal oxide sols and their application as gas-sensing materials

摘要

SnO_2, TiO_2, and In_2O_3 sols were prepared by a chemically modified sol-gel process. By injecting the sols into a solution of two components at 160℃ in non-solvothermal conditions, differently crystallized products were obtained, which were finally crystallized and purified by heat-treatments at 500℃. The heat-treatments did not result in remarkable grain growth, as shown by X-ray diffraction and transmission electron microscopy. The mean crystallite size in the heat-treated powders was found to range from 3.5 nm for In_2O_3 to 8.5 nm for TiO_2. Drop-coating of the powders onto alumina substrates allowed the fabrication of gas-sensing devices. The SnO_2 and In_2O_3 based devices were tested to NO_2, displaying outstanding responses even at temperatures as low as 100℃, and fast responses and recovery times.