Structural and Transport Properties of Fine CoTi-ZnBaM Hexagonal Ferrite

A series of polycrystalline samples of the system Ba1-xZn xCoxTixFe12-2xO19 (x = 0.0, 0.2, 0.4 and 0.6) were prepared by the usual ceramic technique. X-ray diffraction, thermal conductivity, thermoelectric power, drift mobility and phonon frequency were studied for the samples. The X-ray diffraction pattern confirms the presence single phase magnetoplumbite structure of substituted M ferrite samples. The thermal conductivity and thermoelectric power were determined at different temperatures for all the samples. The thermal conductivity coefficient, k, increases with increasing temperature due to the increasing in the number of photons, whereas the decreasing in, k, with increases doping ratio may be due to the formation of anion vacancies. The thermo-electric power measurements reveal the p-type semiconducting behavior of the samples. The increasing in drift mobility with temperature indicates that the hopping of electrons between Fe3+- Fe2+ and holes Co2+- Co3+ are activated by temperature as well as its concentration. So, it is presumed here that the conduction mechanism depends on the hopping of localized charge carriers. Due to the less value of activation energy (less than 0.3 e V) small polaron hopping can be ruled out from conduction process. Thermoelectric power data indicated that the band conduction theory can be participating in the conduction mechanism. The phonon frequency was estimated to have an optimum value for higher substitution, due to the increase in phonon scattering.