Thin films of a hydrated phase of tungsten oxide, viz. hydrotungstite, have been prepared on glass substrates by dipcoating
method using ammonium tungstate precursor solution. X-ray diffraction shows the films to have a strong
b
— axis orientation. The resistance of the films is observed to be sensitive to the humidity content of the ambient, indicating possible applications
of these films for humidity sensing. A homemade apparatus designed to measure the d.c. electrical resistance in response to
exposure to controlled pulses of a sensing gas has been employed to evaluate the sensitivity of the hydrotungstite films towards
humidity.
Keywords Tungsten oxide - hydrotungstite - humidity sensing