Dip-coated hydrotungstite thin films as humidity sensors

Abstract

Abstract. Thin films of a hydrated phase of tungsten oxide, viz. hydrotungstite, have been prepared on glass substrates by dip-coating 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.

Microstructural analysis and electrical conductivity of hexagonal WO3 thin films during annealing

“…9c), we suppose that the conductivity of tungsten oxide films is governed by the non-stoichiometry of WO 3 considered as an n-type semiconductor and we assume that the non-stoichiometry originates only from oxygen vacancies of WO 6 octahedra. Results of WO 3 thin film conductivities and their interpretation as non-stoichiometries originating from surface oxygen vacancies are compatible with many similar works which have been carried out in the fields of WO3 thin films as sensing materials for the detection of atmosphere pollutants [25][26][27][28][29][30][31].…”

Synthesis, Separation and Electrical Properties of WO3-xNanopowders via Partial Pressure High Energy Ball-Milling

“…The conductivity further increases and the value of activation energy of WO 2.7 NP is about 0.28(3) eV which corresponds to n-type semiconductor-like behavior. Results of WO 3 NPs conductivities and their interpretations as non-stoichiometric (process A) and hydrate (process B) originates from oxygen vacancies and are compatible with similar works that have been carried out in study of WO 3 thin films as a sensing material for detection of atmosphere pollutants [25][26][27][28][29][30][31].…”

In situ HT‐XRD Study on the Formation of Hexagonal Ammonium Tungsten Bronze by Partial Reduction of Ammonium Paratungstate Tetrahydrate

“…[1][2][3] Among the possible constituents of "tungsten blue oxide" (an X-ray amorphous phase, WO 3 , WO 2.9 , WO 2.72 , WO 2 and tungsten bronzes [1,2,[4][5][6][7] ), hexagonal ammonium tungsten bronze may have an important role in the doping process because of its ion-exchange property. [4,5,8,9] Furthermore, for applications in electrochromic devices, [1,[10][11][12][13][14] humidity [15,16] and gas sensors [17][18][19][20][21] as well as secondary batteries, [22] metastable tungsten oxides and oxide bronzes have attracted much attention in the past decades due to their open-tunnel structures. [1,2,23,24] Hexagonal ammonium tungsten bronze is an interesting member of tion of the title compound has been discussed.…”