Thermal conductivity of Zn doped CoFe2O4 ferrites

A series of samples of the type Co_1-xZn_xFe₂O₄ (x = 0.0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8 and 1.0) was prepared as ceramics. The existence of a single phase was confirmed by x-ray studies. The thermal conductivity and specific heat were measured at temperatures ranging from 100°C to 200°C. The thermal conductivity had a minimum value at x = 0.4, caused by maximum scattering of thermal phonons which arose from the change of crystal size and excess of lattice vacancies. The phonon frequency was estimated to have an optimum value at x = 0.4, resulting from maximum porosity which disturbs the propagation of the thermal waves.