Transport properties of Ti-Ni spinel ferrites

Polycrystalline ferrites with the composition TixNi(1 + x)Fe(2 - 2x) (0 <= x <= 0.625) were prepared by a double sintering ceramic method. Results of DC electrical resistivity, rho(DC), versus a temperature ensured that the samples possess a serniconcluctive character. Results of Seebeck coefficient S reveal that pure Ni ferrite is n-type semiconductor while the sample with x=0.625 is p-type semiconductor over the whole range of temperature. However, for other samples, 5 shows a transition from p-type to n-type semiconductor with increasing temperature. On the basis of rho(DC), S and rho(AC), the conduction mechanism of NiTi ferrite was determined. (C) 2015 Elsevier B.V. All rights reserved