A study of NTC thermistor fabrication from yarosite mineral had been carried out. Raw yarosite mineral was solved using HCl solution, precipitated using NH4OH and heated at calcination temperature of 700oC for 2 hours. Purified powder and raw yarosite mineral were pressed with pressure of 3.9 ton/cm2 into pellets and sintered at 1100-1300oC in air for 1 hour. The sintered pellets were evaluated using XRD, optical microscope and SEM. Resistivity-temperature characteristic (R-T curve) was determined through measurement of resistivity at various temperatures (room temperature to 100oC). Thermistor pellets made of raw yarosite had a very low density because of its large particle size and of high concentration impurities. Thermistor constant derived from R-T urves showed that the yarosite and the processed powder have a good potential for NTC thermistors due to their relatively high thermistor constant (6220oK for yarosite ore and 2396oK for processed yarosite). However, the room temperature resistivity of the thermistors was very high where the room temperature resistivity of the termistors made from ore yaroste was much higher than that of the termistors made from processed one. XRD data showed that all of the pellets sintered at 1100-1300oC had matrix of Fe2O3 (hematite, hexagonal structure). The data of density, microstructure and electrical properties showed that the thermistors from processed yarosite sintered at 1100oC fit market requirements.Key words : thermistor, NTC, yarosite, electrical characteristics.
P3TkN – BATAN Bandung
P3TkN – BATAN Bandung
