Microstructure dependent thermophysical properties of Ni-Zn ferrite-BaTiO₃ functionally graded ceramics

The purpose of this work was to examine the microstructure dependent thermophysical properties of a mixture of two materials. These were a dielectric powder based on BaTiO3 and a magnetic Ni–Zn ferrite. The thermophysical properties of the ceramics were studied as a function of the dielectric volume fraction in the magnetic powder.

For the thermal expansion coefficient, the experimental results were compared with different theoretical models used for functionally graded materials. The percolation theory was found to be a good model for Ni-Zn ferrite–BaTiO3 functionally graded ceramics. Two percolation thresholds were found and a fourth-order polynome fitted all the experimental data of the thermomechanical properties.