A study on temperature dependent dielectric relaxation behaviour and conduction mechanism of La and Ti co-doped bismuth ferrite.

A series of La and Ti co-doped bismuth ferrite ceramics have been synthesized using the modified sol–gel approach and their crystal structures were verified using X-ray diffraction. Complex impedance analysis has been used to examine the conduction mechanisms and microscopic dielectric relaxations in all of these materials. To examine the behaviour of the dielectric constant's dispersion, the modified Debye's function has been utilized. The dielectric characteristics of each sample have been described using the brick-layer model. In order to understand the conduction mechanism, relaxation period and activation energies, Arrhenius equation and Jonscher's power law were used. The dc conductivity (σDc) decreases significantly by increasing the co-doping percentage of La and Ti which indicates that the dielectric properties of the BFO is improved by the co-doping. The Jonscher's power law fitting parameters indicate that the correlated barrier hopping (CBH) conduction model is followed in all the co-doped samples. Moreover, Electric modulus spectroscopy and the observed values of activation energies suggests the localized and long-range relaxation processes, which are basically non-Debye type relaxation processes. The minimum value of dielectric loss factor was obtained for 10% of La and Ti co-doping. The observed trend in values of activation energies also suggests that the best dielectric properties are obtained for the 10% of La and Ti co-doping in BFO and it retain high dielectric constant up to higher temperature. [ABSTRACT FROM AUTHOR]