Magnetic properties of Ni-Zn ferrites prepared by microwave sintering method

Abstract

The effect of zinc ion substitution for nickel on structural and magnetic properties of NiZn ferrites is reported. The spinel ferrite system Ni 1-x Zn x Fe 2 O 4 with x0 0.2, 0.3, 0.4 and 0.5 was prepared by microwave sintering method. The uniaxially pressed samples were sintered at various temperatures such as 900°C, 1000°C and 1100°C for 30 min. X-ray diffraction patterns of the samples indicate the formation of single-phase cubic spinel structure. SEM micrographs show that grain size increases with increasing zinc content and sintering temperature. The elemental composition of these ferrites was analyzed by EDS. Lattice constant increases with increase in zinc content, obeying Vegard's law. The effect of composition and sintering temperature on initial permeability as the function of frequency and temperature was studied. The initial permeability of NiZn ferrite increases greatly with increasing Zn content and sintering temperature. The dependence of initial permeability with respect to temperature shows the decrease in the Curie point with increase in zinc content, is the normal behavior of ferrites. The relative loss factor ðtan d μ i = Þ of the order of 10 −2 to 10 −5 in the frequency range from 100 Hz to 1 MHz indicates that the prepared ferrites have relatively high purity.

Microwave Sintering of Nanocrystalline Ni1−xZnxFe2O4 Ferrite Powder and Their Magnetic Properties

“…Compared with the initial permeability of conventional‐sintered samples, the difference in initial permeability value is attributed to larger density and grain size observed in microwave‐sintered samples. The average grain size of a microwave‐sintered sample at 1170°C for 30 min is about four times that of the conventional‐sintered sample at 1200°C for 120 min, and it is less than that of microwave‐sintered samples by using solid‐state synthesized Ni 1−x Zn x Fe 2 O 4 ferrite powder . Larger grains consist of a high concentration of domain walls, and minimal energy is sufficient to move domain walls.…”

“…The average grain size of a microwave-sintered sample at 1170°C for 30 min is about four times that of the conventional-sintered sample at 1200°C for 120 min, and it is less than that of microwave-sintered samples by using solid-state synthesized Ni 1Àx Zn x Fe 2 O 4 ferrite powder. 27 Larger grains consist of a high concentration of domain walls, and minimal energy is sufficient to move domain walls. The initial permeability is a result of the easy reversal of domain wall displacement in the direction of the applied magnetic field.…”

Development of Metal Matrix Composites Using Microwave Sintering Technique

“…Microwave sintering has attained global acceptance because of superior benefits over the traditional sintering techniques. The characteristic (Figure 1) of microwave heating is basically different from conventional heating [6]. For conventional heating, an external heating element is used for heat generation and then it transferred to the test materials through convention, conduction, and radiation.…”

Characterization and Electromagnetic Studies on NiZn and NiCuZn Ferrites Prepared by Microwave Sintering Technique

“…Figure 1 shows the experimental settings in the microwave oven. The general configuration of the microwave furnace has been described elsewhere [11]. The NiZn and NiCuZn ferrites with the respective compositions of Ni 0.40 Zn 0.60 Fe 2 O 4 and Ni 0.35 Cu 0.05 Zn 0.60 Fe 2 O 4 were prepared using the microwave sintering method.…”