Investigation of structural and electrical properties of silico-ferrite of calcium (SFC) in the Fe_2O_3-CaO-SiO_2 system synthesized by solid-state reaction

摘要

Silico-ferrite of calcium (SFC) was synthesized through a solid-state route. The phase purity of the sample was characterized by means of X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). X-ray absorption fine structure (XAFS) spectroscopic analysis was used to determine the structure, and the results showed that SFC possesses more Fe-O tetrahedral structure than similarly structured silico-ferrites of calcium and aluminum (SFCA) and verified the existence of a small amount of Fe2+ in SFC. Ac impedance spectroscopy was used to evaluate the electrical properties of SFC, and the results showed that SFC had the properties of a negative temperature coefficient (NTC) thermosensitive material, and indicated that Si4+ donor doping leads to free electrons during the synthesis of SFC. The correlated barrier hopping (CBH) mechanism was proposed for the ac conduction mechanism of SFC, and Si4+ donor-doped SFC exhibited high electronic conductivity at temperatures greater than 102 degrees C.