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The purpose of this paper is to show how to obtain better response, selectivity and fast response and recovery from nanocrystalline ZnO‐based gas sensors as compared to conventional materials.

Nanocrystalline ZnO powders were prepared from the ultrasonic spray pyrolysis method. Aqueous solution of zinc acetate was atomized using ultrasonic atomizer. The aerosol generated was fed to the reaction furnace for pyrolysis. Nanocrystalline ZnO crystallites were collected using simple but novel trapping system. Thick film resistors of this powder were fabricated using screen printing technique.

As‐prepared powder was studied using X‐ray diffraction, transmission electron microscopy and scanning electron microscopy to know structure, size of nanocrystallites and microtopography, respectively. Absorption spectroscopy is used to determine the band gap energy. The gas‐sensing performance of this film was tested.

The sensor was found to be the most sensitive to NH₃. It gives better response, selectivity and fast response and recovery as compared to conventional materials‐based thick films.