Preparation and application of SiO₂-TiO₂ porous glasses to humidity-sensor elements

Abstract

SiO₂-TiO₂ porous glasses were prepared from SiO₂-TiO₂-B₂O₃-Na₂O glasses by means of the phase-separation method. The performance as humidity-sensor elements were examined by the electric resistivity according to the relative humidity change. The porous glass containing 25 mass% of TiO₂ showed good performance in the machine processing and the sensibility of humidity.
The preparation at low phase-separation temperature (773K) gave the porous glasses with small diameter pores and large specific surface area. The electric resistivity extensively of them changed from 30 Ωm to 15 × 10⁶ Ωm with relative humidity change. Leaching the porous glass element in NaOHaq. shortened the response time without changing the electric resistivity.