A catalytic combustion type gas sensor using a positive temperature coefficient (PTC) thermistor, which shows a sharp resistance change around curie temperature (Tc), was investigated for detection of H2 gas. Donor-doped barium titanate (Ba0.998La0.002TiO3) was prepared through solid state reaction and oxalic decomposition methods. La-doped BaTiO3 obtained by the oxalic decomposition method showed excellent PTC properties because of the formation of fine particles, as compared with that prepared with the solid state reaction method. The resulting sensor device showed a fairly high H2 sensitivity in the range of 100 to 1000 ppm.
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