Development of nanocrystalline Mn-Zn ferrites for high frequency transformer applications

Microwave-Hydrothermal (M-H) method has been successfully used for the synthesis of nanocrystalline Mn-Zn ferrites which are used for high-frequency applications. As synthesized powders were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The nanopowders were annealed at 600 °C/20 min using the microwave sintering method. The frequency dependence of dielectric constant (ε′) was measured in the range of 10 Hz-1.3 GHz and initial permeability (μ_i) was measured in the range of 10 Hz-1 MHz. The total power loss (P_t) was measured on the annealed samples at 100 kHz and 200 mT condition. Conductor-embedded-ferrite transformers were fabricated and output power (P_o), efficiency (η) and temperature rise (ΔT) were measured at sinusoidal voltage of 25 V at 1 MHz. The transformer efficiency (η) was found to be high and surface rise of temperature (ΔT) is very low.