Multilayer Chip Inductor Applications Research Articles

A comprehensive study on structural, magnetic and dielectric properties of Ni0.3Cu0.3Zn0.4Fe1.8Cr0.2O4 nanoparticles synthesized by sol-gel auto combustion route

Ni0.3Cu0.3Zn0.4Fe1.8Cr0.2O4 (NCZF) ferrite nanoparticles (NPs) were prepared by sol-gel auto-combustion route. As obtained NCZF powder NPs from sol-get auto combustion route were divided into four parts equally. A non-calcinated part of NCZF NPs was considered as SS1 sample, whereas the three separated parts of NCZF NPs were calcinated at 400°C, 600°C and 800°C, accordingly and were considered as SS2, SS3 and SS4 samples, respectively. X-ray diffraction (XRD) patterns of as-prepared samples were used to evaluate the microstructure parameters. The obtained crystallite sizes were found to be 25, 26.5, 23.4 and 28.1 nm for SS1, SS2, SS3, and SS4 samples, respectively. Transmission electron microscopy images of samples exhibit the spherical shape particles. Average particle size was found to be 6.18, 8.24, 12.7, and 17.14 nm from particles size distributions of SS1, SS2, SS3 and SS4 samples, respectively. The saturation magnetization MS(45.96, 49.84, 48.84 and 50.01 (emu/g), coercivityHC(41.40, 43.00, 44.06, and 43.69 Oe), and remanant magnetization Mr(2.00, 1.85, 1.88 and 1.92 emu/g) were determined from M-H analysis of as-prepared samples. Surface analysis of SS2, SS3 and SS4 samples were examined by X-ray photoemission spectroscopy. Dielectric properties and real value of electric modulus of SS4 sample were reduced drastically as-compared to SS2 sample. Frequency dependent conductivity and impedance of SS4 sample was enhanced as-compared to SS2. Outstanding structural, dielectric and electric, and magnetic properties of NCZF NPs can be used for the multi-layer chip inductor applications.

Structural and Magnetic Properties of Copper-Substituted Nickel–Zinc Nanoparticles Prepared by Sol-Gel Method

Soft ferrite materials of high magnetic permeability and lower losses, essential to multilayer chip inductor applications, require stringent processing conditions to enable the materials with the desired characteristics. Copper-substituted Ni–Zn nanoferrite was processed through the sol-gel technique using polyvinyl alcohol as a chelating agent to control the particle size. The structural parameters and magnetic properties were examined by X-ray diffraction, field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy and vibrating-sample magnetometer techniques respectively. FESEM images showed the formation of anisotropic structures like nanorods, nanoflower bouquet and nanofibres with copper substitution. The occupancy of copper ions towards octahedral sites has been ascertained by DC resistivity measurements, whereas the magnetic properties have been discussed based on cation distribution. The observed high values of magnetic permeability and DC resistivity suggest that the Ni–Zn ferrite system yields useful electromagnetic properties for smaller concentrations of copper substitution.

Magnetic, Electric and Optical Properties of Mg-Substituted Ni-Cu-Zn Ferrites

The Ni0.25−x Mg x Cu0.30Zn0.45Fe2O4 (x = 0.00 mol, 0.05 mol, 0.10 mol, 0.15 mol, 0.20 mol and 0.25 mol) magnetic oxide system was prepared by a sol–gel auto--combustion method using glycine as a fuel. X-ray diffraction study reveals the formation of pure spinel lattice symmetry along with the presence of a small fraction of unreacted Fe2O3 phase as a secondary phase due to incomplete combustion reaction between fuel and oxidizer. The lattice constant (a) was found to decrease with the increase of Mg2+ content; the average crystallite size (D) is observed in the range of 26.78–33.14 nm. At room temperature, all the samples show typical magnetic hysteresis loops with the decrease of magnetic moment (n B) of Ni-Cu-Zn ferrites with the increase of Mg2+ content. The intrinsic vibrational absorption bands for the tetrahedral and octahedral sites of the spinel structure were confirmed by infrared (IR) spectroscopy. The optical parameters such as refractive index (η), velocity of IR waves (v) and jump rates (J 1, J 2, J) were studied and found to be dependent on the variation of the lattice constant. The Curie temperature (T c) of Ni-Cu-Zn mixed ferrite was found to decrease with Mg2+ addition. The composition x = 0.15 mol.% with a low dielectric loss tangent of 2% seems to have potential for multilayer chip inductor applications at a wide range of frequencies.

Comparative Study of Structural, Electrical, and Magnetic Behaviour of Ni-Cu-Zn Nanoferrites Sintered by Microwave and Conventional Techniques

Ni0.8-xCuxZn0.2Fe2O4 spinel type ferrite nanoparticles have been synthesized by citrate precursor method. These nanoparticles were then given heat treatment using microwave and conventional sintering techniques. Various characterizations using X-ray powder diffraction (XRD), scanning electron microscope (SEM), LCR meter, and B-H loop tracer were carried out on the sintered specimens. The XRD spectra of these ferrites confirmed the formation of spinel structure. The average crystallite size calculated using Scherrer’s formula was found to be in the nanometer range, its value varying from 33 nm to 39 nm. Microwave sintered samples exhibited superior electrical and magnetic behaviour over their conventionally sintered counterparts. Feasibility of low temperature synthesis and promising properties will render these ferrites suitable for multilayer chip inductor applications.

Effect of Cu2+ substitution on structural and magnetic properties of Ni–Zn ferrite nanopowders

In this study copper substituted nickel–zinc ferrite powders with the general composition Ni0.6−xCuxZn0.4Fe2O4 (x = 0, 0.05, 0.1, 0.15, 0.2, and 0.25) were prepared via auto-combustion sol–gel method. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy, Mossbauer spectroscopy, vibrating sample magnetometer (VSM) and superconducting quantum interference device analysis were carried out in order to characterize the structural and magnetic properties of particles. The XRD results confirmed the formation of single phase spinel ferrite particles for all of the samples. The results of FTIR analysis indicated that the there are two main frequency bands, namely, the high frequency band observed at ~577 cm−1 and the low frequency band observed at ~450 cm−1. These two bands correspond to the intrinsic vibrations of tetrahedral and octahedral Fe3+–O2− complexes, respectively, and are the characteristics of all the ferrite materials. The size of particles was around 80–800 nm. The VSM results revealed that with an increase in the amount of copper in ferrites, the saturation magnetization increased. Saturation magnetization increased to 97 emu/g for x = 0.05 at room temperature and increased to 261 emu/g for x = 0 and 0.05 at 2 K. The results indicated that the powder is suitable for the application in multilayer chip inductor due to its low temperature sinterability and good magnetic properties.

Study of electrical and dielectric behavior of Tb+3 substituted Y-type hexagonal ferrite

A series of Y-type hexa-ferrites with composition, Ba2Zn2TbxFe12−xO22 (0⩽x⩽0.1), were synthesized by the sol–gel auto-combustion technique. The X-ray powder diffraction technique was employed to confirm the formation of Y-type phase. The dispersion in dielectric constant, dielectric loss, and σac with frequency shows that the dispersion at low frequencies is due to Maxwell–Wagner type of interfacial polarization in general and the hopping of charge carrier between Fe2+ and Fe3+ ions. The substitution of Tb+3 inhibit the valence exchange of Fe+2 and Fe3+ and therefore the dielectric permittivity decreased. The DC resistivity increased from 7.29×107 to 4.73×108Ωcm with increasing Tb-contents due to the unavailability of Fe3+ ions at octahedral sites. The enhanced resistivity of Y-type hexa ferrites makes them suitable candidates for multi-layer chip inductor applications.

Bi2O3 liquid phase assisted and Mn substituted permeability and magnetic properties of Ni-Cu-Zn ferrite for multilayer chip inductor application

In the present work, low-temperature fired MnxNi0.5−xCu0.25Zn0.25Fe2O4 + Bi2O3 (x = 0.0 to 0.45) was synthesized by the sol-gel auto combustion technique at a temperature of 1073 K. Bi2O3 (with 2 wt. %) was used as a sintering aid for improving the density, microstructure and lowering the sintering temperature of Mn-Ni-Cu-Zn ferrites. Synthesized samples were investigated for their structural, magnetic, and electrical properties such as density, porosity, saturation magnetization, and permeability as a function of Mn2+ substitution. Permeability and saturation magnetization were found to increase with the replacement of Ni2+ with Mn2+. Bulk density of 4.5 g/cm3 was observed for Mn-Ni-Cu-Zn ferrite with Bi2O3 additives which is greater than that of pure Mn-Ni-Cu-Zn ferrite (4.1 g/cm3). Saturation magnetization of NiCuZn ferrite increased from 37 to 63 emu/g with increase in Mn2+ substitution. Mn substituted NiCuZn ferrite shows higher complex permeability (μ′ = 672) than that of the pure NiCuZn ferrite (μ′ = 433). Curie temperature determined from temperature dependent permeability data shows that Tc attains maximum value of 707 K.

SOFT MAGNETIC PROPERTIES OF Mg0.7-xNi0.3ZnxFe2O4 FERRITES SYNTHESIZED BY SOL-GEL AUTO-COMBUSTION TECHNIQUE WITHOUT POST-PREPARATION THERMAL TREATMENT

Single phase nanocrystalline soft magnetic Mg 0.7-x Ni 0.3 Zn x Fe 2 O 4, ferrites with x = 0.0 − 0.7 were prepared by sol gel auto-combustion method. X-ray diffraction confirms the formation of single phase nano-crystalline cubic spinel ferrites with average grain diameter ranging between 12.9 nm to 23.9 nm. Formation of the ferrite phase without subsequent heat treatment makes sol-gel auto combustion technique especially suitable and economical for the large scale industrial production of the nano-crystalline ferrites for multilayer chip inductor applications (MLCI). Both, lattice parameter and X-ray density shows a linear increase with increasing Zn 2+ concentration, attributed to the difference in ionic radii and density of Mg and Zn . Increase in Zn content enhances the soft magnetic behavior, exhibiting linear decrease of coercivity from 122.34 Oe to 72.45 Oe, explained by increase of density with Zn addition. The maximum magnetization (Mmax)increases up to 0.106 Tesla (for x = 0.4) and. then decreases with increase of Zn content, discussed on the basis of increase of the occupancy of A-site in spinel ferrite by non-magnetic Zn 2+ ion.

Microwave sintering of iron deficient Ni–Cu–Zn ferrites for multilayer chip inductors

This study was aimed at the low temperature synthesis of iron deficient samples of Ni–Cu–Zn ferrite using the microwave sintering technique. The samples were sintered at 950 °C for 30 min. Microstuctural and structural analyses were carried out using a scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The lattice parameter was found to increase with increasing nickel concentration. The porosity calculated using X-ray density and measured density also shows a decreasing behavior with increasing nickel concentration. The variation of saturation magnetization was studied as a function of nickel concentration. All the compositions indicate that they are ferrimagnetic in nature. Initial permeability plotted against temperature at 10 kHz showed a sharp drop at Curie transition temperature and values observed at transition are found to be dependent on the nickel concentration. The dielectric constant, dielectric loss tangent and ac conductivity of all samples were measured at room temperature as a function of frequency. These parameters decrease with increase in frequency for all of the samples. The present ferrites are well suitable for the application in multilayer chip inductor due to its low temperature sinterability, good magnetic properties and low loss at high frequency.

Influence of copper substitution on magnetic and electrical properties of MgCuZn ferrite prepared by microwave sintering method

Polycrystalline MgCuZn ferrites with chemical formula Mg 0.50-xCu xZn 0.50Fe 2O 4 ( x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) were prepared by microwave sintering method. These powders were calcined, compacted and sintered at 950 °C for 30 min. Structural, microstructural and elemental analyses were carried out using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectrometry (EDS), respectively. The lattice parameter is found to increase with increasing copper content. A remarkable densification is observed with the addition of Cu ions in the ferrites. The sintered ferrite was characterized for initial permeability, dielectric constant and dielectric loss tangent and ac conductivity measurements. The temperature variation of the initial permeability of these samples was carried out from 30 °C to 200 °C. The dielectric constant, dielectric loss tangent and ac conductivity have been measured in the frequency range of 100 Hz to 1 MHz. Initial permeability and dielectric constant were found to increase and dielectric loss decreased with Cu substitution for Mg, up to x = 0.20. The ferrite powder prepared is suitable for the application in multilayer chip inductor due to its low-temperature sinterability, good magnetic properties and low loss at high frequency.

Influence of zinc substitution on magnetic and electrical properties of MgCuZn ferrite nanocrystalline powders prepared by sol–gel, auto-combustion method

The ferrite compositions Mg 0.80− x Cu 0.20Zn x Fe 2O 4 with x = 0.5, 0.55, 0.60 and 0.63, were synthesized through nitrate–citrate gels auto-combustion method. The autocatalytic nature of the combustion process has been studied by thermal analysis (DTA and TG) of the dried gels. The as-burnt powders were calcined at 800 °C for 1 h and then pressed ferrite parts were sintered at 900 °C for 4 h. The as-burnt powders and calcined powders were characterized with respect to phase identification, grain size and lattice parameter determination using X-ray diffraction. The sintered ferrites have been investigated for their electrical and magnetic properties such as saturation magnetization, initial permeability, AC-resistivity, dielectric constant, dielectric loss tangent as a function of zinc content. The initial permeability, saturation magnetization, dielectric constant and dielectric loss were found to increase and AC-resistivity was decreased with Zn substitution for Mg. The powder prepared is suitable for the application in multilayer chip inductor due to its low-temperature sinterability, good magnetic properties and low loss at high frequency.

Characterization of nanocrystalline NiCuZn ferrite powders synthesized by sol–gel auto-combustion method

The ferrite compositions Ni0.8−xCu0.2ZnxFe2O4 with x = 0.5, 0.55 and 0.6, were synthesized through nitrate–citrate gel auto-combustion method. The autocatalytic nature of the combustion process has been studied by thermal analysis (DTA and TG) of the dried gels. The powders were calcined at 700 °C/2 h and then pressed ferrite parts were sintered at 900 °C/4 h. The ferrite was characterized with respect to phase identification, crystallite size and lattice parameter determination using X-ray diffraction. As-burnt powders showed the presence of crystalline cubic spinel ferrite with about 19–22 nm crystallite sizes. The densification characteristic of the powder was investigated using TMA. The sintered ferrite was characterized for permeability, saturation magnetization, relative loss and ac resistivity measurements. The permeability and magnetization were found to increase and magnetic loss, ac resistivity were decreased with Zn substitution for Ni. The powder is suitable for the application in multilayer chip inductor due to its low temperature sinterability, good magnetic properties and low loss at high frequency.

Sintering characteristics and magnetic properties of NiCuZn ferrites for MLCI applications

We proposed and experimentally verified that nanocrystalline ferrite particles (NFPs) additive was effective on improving the densification behavior and magnetic properties of the NiCuZn ferrites for multilayer chip inductor (MLCI) applications. The NFPs, which have high surface free energy, spread around the micron-sized ferrite particles (MFPs) and increased contacting area and inter-diffusion of the particles. As a result, densification behaviors of the samples were improved. The sample with 30 wt% NFPs additive exhibited the highest initial permeability when sintered at 900 °C. It was mainly attributed to relatively larger grain size and higher sintering density, and no other sintering aids with different chemical composition were added. Q-factor increased monotonously with the content of NFPs, which was attributed to the decrease of grain size and increase of sintering density. The MLCIs made by the ferrite with 30 wt% NFPs also exhibited better properties than that made by the ferrite with 1.5 wt% Bi 2O 3 due to less diffusion of Ag electrode to ferrite and higher initial permeability.

Preparation of ultrafine silver powder using ascorbic acid as reducing agent and its application in MLCI

The preparation of ultrafine silver powder with chemical reduction method was investigated. Ascorbic acid was employed as reducing agent. Reaction of AgNO 3 with ascorbic acid gives polyhedron monodispersed ultrafine silver powder. Effect of reaction temperature on particles was studied. The average congeris sizes ( D 50) reduces linearly from 3.1 μm to 1.0 μm as the reaction temperature increases from 20 °C to 60 °C. The silver powder having excellent dispersibility and different size was prepared through different pH value or different dosage surfactant. The TG/DTA of silver was discussed with thermal analyzer. As-prepared silver powder was applied in ferrite multi-layer chip inductor (MLCI). The silver end termination has high adhesion strength, excellent solderability and solder leaching resistance behavior.

Copper ions influence on the physical properties of a magnesium-zinc ferrite

The effect of Cu substitution on the properties of magnesium-zinc ferrites sintered at low temperature were investigated. The densification of MgCuZn ferrite is dependent upon Cu concentration in the composition of Mg 0.5 − x Cu x Zn 0.5Fe 2O 4 + 0.5MgO. The sintered ferrite with a density of about 4.5 g/cm 3 and the electrical resistivity greater than 10 8 Ω cm was obtained at relatively low sintering temperature (1050°C), for x = 0.3. This sintering condition is suitable for multilayer chip inductor application.

Low Temperature Sintered Ni-Zn-Cu Ferrite

The low temperature sintering of Ni-Zn-Cu ferrite has been investigated by usual ceramic technique. The sintering density and the permeability of the sintered ferrite were strongly affected by the size of the starting oxide powders and the pro-sintering temperature. It was most effective to utilize fine particles of iron oxide and to calcine at about 800°C for the preparation of high permeability ferrite. The sintered ferrite with a density greater than 4.5g/cc and the permeability at 10MHz greater than 200 was obtained at relative low sintering temperature (about 900°C). This condition is suitable for multilayer chip inductor application.