Microwave sintering of Ni–Zn ferrites: comparison with conventional sintering

Ni1−xZnxFe2O4 with x=0.0–1.0 in steps of 0.2 have been densified to >95% of theoretical both by conventional and microwave sintering procedures. Comparison studies were performed on these samples sintered at 1275 °C for 30 min. Microstructural study revealed large, but fewer pores in the microwave sintered specimens and small, but substantially more pores in the case of conventionally sintered specimens. Magnetic properties measurements showed lower coercivity and higher magnetization values for microwave sintered specimens. Lower coercivity values observed in microwave sintered specimens are attributed to larger grain size and higher magnetization values may be explained by the contribution of the ‘microwave field’ to the ‘uncoupling spin effect’. Most significantly samples sintered in a microwave field, generally, showed lower dielectric constant values compared with the samples sintered conventionally, making microwave sintering particularly suitable for high frequency applications.