Microstructural influence on the broadband dielectric properties of BaTiO3-Ni0.5Zn0.5Fe2O4 core-shell dcomposites: Experiment and modeling

Dielectric measurements of core-shell BaTiO3-Ni0.5Zn0.5Fe2O4 ferroelectric-ferrimagnetic composites, sintered at two temperatures (1050 degrees C and 1150 degrees C), were performed in a broadband frequency range of 10Hz-1 THz at various temperatures of 100-500 K. The comparison of temperature dependences reveals a drastic change of permittivity as a function of sintering temperature, as a result of modifications induced on the microstructural parameters as grain size and density. Effective medium approach was used in order to better describe processes associated with the constituent composite phases. Complex specific resistivity coupled with Maxwell-Wagner-Hashin-Shtrikman model allowed to associate lower frequency processes with grain boundary effects. We concluded that the main factor influencing the electrical properties of core-shell composites is the structure and interfaces, instead of the constituent materials themselves. (C) 2015 AIP Publishing LLC.