Microstructure dependent thermophysical properties of Ni-Zn ferrite BaTiO3functionally graded ceramics

The purpose of this work was to examine the microstructure dependent thermo physical properties of a mixture of two materials. These were a dielectric powder based on BaTiO3 and a magnetic Ni-Zn ferrite. The thermophysical pro perties of the ceramics were studied as a function of the dielectric volume fraction in the magnetic powder. For the thermal expansion coefficient, th e 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 per colation thresholds were found and a fourth-order polynome fitted all the e xperimental data of the thermomechanical properties. (C) 1999 Kluwer Academ ic Publishers.