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Gas sensing properties of 1-D ZnO obtained by hydrothermal process

G. TELIPAN1,* , L. PISLARU-DANESCU1, V. MARINESCU1, P. PRIOTEASA1, G. ZARNESCU1

Affiliation

  1. National Institute for Electrical Engineering ICPE-CA, Splaiul Unirii 313, sector 3, Bucharest, Romania

Abstract

ZnO was obtained by hydrothermal process using Zn(CH3COO)2x2H2O like precursor and cationic surfactant tetra-n-buthylammonium bromide-TBAB. The molar ratio surfactant/Zn precursor was 0.6. The gel obtained was stirring for 24 hours and transferred to an autoclave for 3 days at the 1000C. The obtained powder was calcined at 500oC for 2 hours and pressed in the disc form with the dimensions 6x1 mm at 2 tone force/cm2. For the sensor fabrication, the disc was mounted on the transistor ambasis. TGA of the uncalcined sample under air static and 10oC/min heating rate, showed the loss of the water below 81.8 ºC and surfactant loss started at 164-186.3 ºC being completely removed at about 450 ºC. X-ray diffraction was effected on the calcined powder where was obtained a cristalline structure type hexagonal wurtzite with lattice constants a=0.324982 nm and c=0.520661 nm, crystal domain size is estimated to be 48.9 nm using Debye-Scherrer. The N2 adsorption desorption isotherm shows that the powder calcined ZnO is composed by the mesopores and micropores. The specific surface area determinated by BET method was 6 m2/g. ZnO disc was scanned using white light interferometry technique and the profilograms show the maximum surface peaks are around 27 μm and maximum valleys dimensions are 24 μm. The average roughness that exists on all selected areas was 2 μm. The sensor was tested in dynamic regime in the conditions: the flow of 300 cm3/min CO2 at the 25, 50 and 70oC gas testing chamber temperature and was measured the voltage values in function of the time. The maximum voltage values obtained were 320 mV, 430 mV and 245 mV corresponding for 25, 50 and 70oC respectively and after 6, 4 and 5 minutes gas exposure..

Keywords

Semiconductor oxide, Zinc oxide, Thermal analysis, BET isotherms, Gas sensing properties.

Citation

G. TELIPAN, L. PISLARU-DANESCU, V. MARINESCU, P. PRIOTEASA, G. ZARNESCU, Gas sensing properties of 1-D ZnO obtained by hydrothermal process, Optoelectronics and Advanced Materials - Rapid Communications, 5, 6, June 2011, pp.643-647 (2011).

Submitted at: March 12, 2010

Accepted at: June 9, 2011