Structure, infra-red, dielectric properties and conduction mechanism of Ti and Cu-Ti co-doped bismuth ferrite (BiFeO3): a comparison study

Multiferroic compositions BiFe0.90Ti0.10O3 and BiFe0.885Cu0.015Ti0.1O3 were synthesized by solid-state mixed oxide method. XRD studies confirmed rhombohedral crystal structure for both compositions while a little change in lattice parameters was observed with Cu-Ti co-doping. SEM analysis indicate that with co-doping comparatively smaller grains were evolved in the microstructure. Fourier-transform infrared spectroscopy (FTIR) was conducted to study absorption bands of different phases. High temperature A.C. conductivity (sigma(ac)) analysis revealed the hopping charge conduction mechanism. Impedance spectroscopy (IS) was employed from room temperature to 230 degrees C in 100Hz-1MHz frequency range to analyze dielectric properties. IS data indicated decline in impedance with increase in temperature and frequency which confirms negative temperature coefficient of resistance (NTCR) behavior. Owing to the resistance-temperature characteristics, these compositions are well suited for thermal sensor applications.