Humidity sensing characteristics of hydrotungstite thin films

Authors: Kunte, G.¹; Shivashankar, S.¹; Umarji, A.²

Source: Bulletin of Materials Science, Volume 31, Number 6, November 2008 , pp. 835-839(5)

Publisher: Springer

Buy & download fulltext article:

Price: $47.00 plus tax (Refund Policy)

Abstract:

Thin films of the hydrated phase of tungsten oxide, hydrotungstite (H₂WO₄·H₂O), have been grown on glass substrates using a dip-coating technique. The b-axis oriented films have been characterized by X-ray diffraction and scanning electron microscopy. The electrical conductivity of the films is observed to vary with humidity and selectively show high sensitivity to moisture at room temperature. In order to understand the mechanism of sensing, the films were examined by X-ray diffraction at elevated temperatures and in controlled atmospheres. Based on these observations and on conductivity measurements, a novel sensing mechanism based on protonic conduction within the surface layers adsorbed onto the hydrotungstite film is proposed.

Keywords: Tungsten oxide; hydrotungstite; humidity sensor; selectivity; protonic conduction

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s12034-008-0133-y

Affiliations: 1: Materials Research Centre, Indian Institute of Science, Bangalore, 560 012, India 2: Materials Research Centre, Indian Institute of Science, Bangalore, 560 012, India, Email: umarji@mrc.iisc.ernet.in

Publication date: 2008-11-01