Vol. 96, Issue 9, September 2008, pp.42-46

Morphological and Humidity Sensing Studies of WO₃ Mixed with ZnO and TiO₂ Powders

^*N. K. Pandey, Anupam Tripathi, Karunesh Tiwari, Akash Roy, Amit Rai,

Priyanka Awasthi, Aradhana Mishra, ¹Alok Kumar

Sensors and Materials Research Laboratory

Department of Physics, University of Lucknow, Lucknow-226007

¹Geological Survey of India, Lucknow

*E-mail: nkp1371965@rediffmail.com, nkp1371965@yahoo.co.in

Received: 17 August 2008   /Accepted: 19 September 2008   /Published: 30 September 2008

Abstract: This paper reports resistive type humidity sensing properties of composite powder of WO₃, ZnO and TiO₂ taken in the ratio of 8:2:1. Tungsten oxide powder has been obtained by oxidizing Tungsten powder (Lobachemie, 99 % pure) at 600 ⁰C. 250 mg of ZnO (qualigens, 99% pure) and 125 mg of TiO₂ (qualigens, 98% pure) have been mixed with 1 gram of WO₃. Pellet of this powder mixture has been made at pressure of 3 tones for half an hour. The pellet has been annealed at temperatures of 300 ⁰C, 400 ⁰C and 500 ⁰C. Humidity sensing application of pellet has been studied in a specially designed chamber. Standard solution of potassium sulphate has been used as humidifier and potassium hydroxide as de-humidifier. Variation in resistances has been noted using Sinometre (MΩ range,VC 9808). Relative humidity is measured using standard hygrometer (Huger, Germany). It has been observed that as relative humidity increases, there is decrease in the resistance of the pellet. After annealing of sample at each temperature, it has been exposed to humidity in the chamber. The mean sensitivity of the pellet is calculated for each annealing temperature. It has been observed that as annealing temperature increases from 300 ⁰C to 500 ⁰C, mean sensitivity increases. This composite material carries a good scope for the development of resistive type humidity sensor.

Keywords: WO_3, ZnO, Hygrometer, Sinometre, Annealing, TiO₂

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