Thongchai Panmatarith, Nibrosulhuda Hayeemayang, and Nipusanee Baka-lee

pp. 1113 - 1122

Abstract

The SnO₂+2CoO and SnO₂+Cr₂O₃
 materials were prepared by standard ceramic techniques and the
phase identified by XRD techniques. The PTC effect was tested. Both samples were applied as temperature
sensors. Sample 1 exhibited PTC effect from 25 to 110ºC and the positive temperature coefficient of the
resistance (α) was +18.2 %/ºC. The maximum resistance was 28.5 MΩ at 110ºC. Sample 2 exhibited PTC
effect from 35 to 85ºC and the positive temperature coefficient of the resistance (α) was +28.6 %/ºC. The
maximum resistance was 91.8 MΩ at 85ºC. The PTC effect was seen to have its origins in the resistance of
the grain boundary region. The PTC effect in both samples was discovered for the first time. The prepared
samples and temperature monitoring with a computer system can measure the temperature in the range
22ºC to 70ºC (sample 1) and 40ºC to 120ºC (sample 2). The working temperature of these sensors are near the
PTC region and they are very sensitive to heat.