Sol-gel processed iron oxide-silica nanocomposite films as room-temperature humidity sensors

Iron oxide-silica nanocomposite films have been fabricated using sol-gel process and spin coating technique. Iron oxide and silica were segregated. As Si content in the films increase, the films were more compact. The iron oxide films calcined at 400 °C were hematite (α-Fe2O3), but in the presence of silica, iron oxide is composed of hematite and magnetite. The response of iron oxide to humidity is improved tremendously in the presence of small amount of silica. The films containing 90:10 Fe:Si show the highest sensitivity. The response is fast and reversible at the operating temperature of 30 °C.