The Effect of Sintering Temperature on Electrical Characteristics of Fe_2TiO_5/Nb_2O_5 Ceramics for NTC Thermistor

摘要

A study on the fabrication of Iron Titanium Oxide (Fe_2TiO_5) ceramics for negative temperature coefficient (NTC) thermistors has been carried out, in order to know the effect of sintering temperature on the electrical characteristic of 1.0 % mole Nb_2O_5 doped Fe_2TiO_5 ceramics.These ceramics were made by mixing commercial powders of Fe_2O_3, TiO_2 and Nb_2O_5 with proportional composition to produce Fe_2TiO_5 based ceramic. The raw pellet was sintered at 1000 °C, 1100 °C and 1200 °C temperature for 2 hours in air. Analysis of the micro structure and crystal structure were performed by using a scanning electron microscope (SEM) and x-ray diffraction (XRD) respectively. XRD spectra showed that the crystal structure of all ceramics of Fe_2TiO_5 made at various sintering temperatures are orthorhombic. The SEM images showed that the grain size of pellet ceramics increase with increasing sintering temperatures. From electrical resistances data that was measured at temperature 30-300 °C, it is found that the value of thermistor constant (B), activation energy (E_a), thermistor sensitivity (a) and room temperature resistance (R_(RT)) decreases with respect to the increasing of sintering temperature. The fabricated Fe_2TiO_5 ceramics have thermistor constants (B= 6394-6959 K). This can be applied as temperature sensor, and will fulfill the market requirement.