Porous zeolite ceramics was fabricated by firing the powder and examined in terms of humidity sensor characteristics at elevated temperatures. The following results are obtained.
(1) The suitable firing temperature for the zeolite powder is found to be in the range of 500° to 700°C in view of the existing phase and the sample strength.
(2) Although the humidity sensitivity at 400°C was small comparing with that at R. T., the hysteresis of the impedance at 400°C on increasing and subsequently decreasing the humidity became negligibly small.
(3) The response time could also be significantly reduced by heating the sample at 400°C comparing with that at R. T.