Electrical and humidity sensing properties of lead(II) tungstate-tungsten(VI) oxide and zinc(II) tungstate-tungsten(VI) oxide composites
Lead(II) tungstate and zinc(II) tungstate were prepared by a solution route and sintered at 973 K in the form of cylindrical discs. Experimental results on PbWO{sub 4} (PW) and WO{sub 3} (WO) composites for humidity sensing are described. Sintered polycrystalline discs of PbWO{sub 4} (PWWO-10), WO{sub 3} (PWWO-01), ZnWO{sub 4} (ZWWO-10) and composites of PW or ZW and WO in the mole ratios 8:2, 6:4, 4:6, 2:8 designated as PWWO and ZWWO-82, 64, 46 and 28, respectively and doped with 2 mol% of Li{sup +} were studied. The composites were subjected to dc conductance measurements over the temperature range 373-673 K in air atmosphere from which activation energies were determined. The activation energy values for dc conductance were found to be in the range of 1.09-1.30 eV. The composites were identified by powder XRD data. The scanning electron microscopy (SEM) studies were carried out to study the surface and pores structure of the sensor materials. The composites were subjected to dc resistance measurements as a function of relative humidity in the range of 5-98% RH, achieved by different water vapor buffers thermostated at room temperature. The sensitivity factor (S{sub f}=R{sub 5%}/R{sub 98%}) measured at 298 K revealed that PWWO-28 and ZWWO-46 composites have the highest humidity sensitivity factor of 17 615{+-}3000 and 2666{+-}550, respectively. The response and recovery time for these humidity sensing composites were good.
- OSTI ID:
- 20888040
- Journal Information:
- Materials Research Bulletin, Vol. 39, Issue 4-5; Other Information: DOI: 10.1016/j.materresbull.2003.12.014; PII: S002554080400008X; Copyright (c) 2004 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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