NiZn Ferrite Thin Films Research Articles

Optimization of visible photoluminescence emission from Ni-Zn ferrite thin films

Ni-Zn ferrite films with different thicknesses were prepared by the spray method, aiming to study the relationship between the annealing effect in an oxygen rich environment and the structural, optical properties and photoluminescence emission. X-ray diffraction (XRD) analysis used with Rietveld refinement showed that all prepared samples had a single spinel phase structure. Likewise, the Fourier transform infrared (FTIR) spectra confirmed the phase formation of Ni-Zn ferrites by appearing in both of the two characteristic absorption bands which are related to the tetrahedral and octahedral sites. For annealed thin film samples of Ni-Zn ferrite, the atomic force microscope (AFM) surface morphology exhibits pinning structure on the surface in nanoscale height, whereas for un-annealed samples, there are hills and valleys cover a broad region. The different electronic transitions were estimated from the UV-visible transmission spectrum. Strong photoluminescence (PL) intensity in the visible range was observed under the excitation of UV radiation. The intensity of the PL signal was strongest at a film thickness of 750 nm then decreased for higher thicknesses. This could be interpreted by using proposed energy level structures based on the transmission spectrum of the investigated samples. The strong PL intensity introduces the samples as a direct optical detector for UV radiation.

Effects of aqueous ethanol solutions on the structural and magnetic properties of NiZn ferrite thin films prepared by spin-spray deposition

Although substrate wettability greatly impacts deposition processes using the spin-spray technique, there are few substrates suitable for the deposition of spin-sprayed ferrite thin films. To tune substrate wettability without changing the type of substrate, we demonstrate a Ni0.17Zn0.52Fe2.31O4 ferrite film deposited by the spin-spray technique on a 0.2 mm glass substrate with 0–5% aqueous ethanol solutions. All samples showed (222) preferential orientation and triangular grain morphology. The effects of aqueous ethanol solutions on the microstructure and magnetic properties of ferrite thin films were also investigated. When the ethanol volume percent concentration equaled 3%, the columnar morphology of the microstructure was most evident and the saturation magnetization and the real permeability reached their maximum values. Because of the shape anisotropy of the columnar structure, the coercivity of the parallel magnetic field increased, whereas the coercivity of the perpendicular magnetic field decreased. First-order inversion curve measurements revealed that ethanol-containing ferrite thin films had a more uniform grain size.

The impact of solvent tanδ on the magnetic characteristics of nanostructured NiZn-ferrite film deposited by microwave-assisted solvothermal technique

Nanostructured Ni-Zn ferrite (NZF) thin films, deposited by a CMOS-compatible microwave-assisted solvothermal deposition (MAS-D) process, exhibit ‘far-from-equilibrium’ distribution of cations in the spinel structure, and thus, exciting magnetic properties. Solvents with different dielectric loss-tangents, such as ethanol (tanδ≈0.94), 1-decanol (tanδ≈0.1), and benzyl alcohol (tanδ≈0.67), were mixed in five judiciously-chosen proportions – ED35 (ethanol:1-decanol=3:5; tanδ≈0.51), ED33 (tanδ≈0.63), EB25 (tanδ≈0.66), EB35 (tanδ≈0.70), and EB33 (tanδ≈0.74) – to study the impact of effective tanδ on cation occupancy and the nature of magnetization in the resulting films. The maximum temperature attained during microwave irradiation (Tmax) and the heating rate (∆T/trise) increase as the effective tanδ of the solvent mixture increases, which in effect leads the Ni atoms to migrate towards equilibrium lattice sites. Unlike bulk NZF, where all Ni atoms occupy octahedral sites (B-sites), the films reported here exhibit just 28% of Ni atoms in B-sites at best when deposited from the precursor solution EB25. At room temperature all films are superparamagnetic, while the maximum moment (MS=100 emu/cc) is observed in the film with the highest % of Ni atoms in B-sites. Thermoremanent magnetization (TRM) of the samples is studied and compared. Very high effective anisotropy constants (Keff=140 kJ/m3), and two-orders-of magnitude-higher inter-particle dipole moment (Edipole≈8×10-20 J @300 K) are observed in samples prepared from benzyl alcohol rather than 1-decanol – signifying the potential for tailoring magnetic properties by the choice of solvents in the MAS-D process.

Anisotropic growth and magnetic properties of nickel–zinc ferrite thin film by spin spray deposition

NiZn ferrite thin films with different compositions were prepared by spin spray deposition on an enhanced ultrasonic system and significant improvements in microstructure and magnetic properties of spin-sprayed thin-films were observed and explained. The formation of triangular grain morphology as a result of anisotropic growth was discussed based on a thin-film growth mechanism, and the preferred (222) anisotropic growth was deduced as the consequence of a uniform, fast-rate deposition of high-quality ferrite thin film by spin spray. First-order reversal curve measurement was adopted to investigate the grain size distribution of the abnormal microstructure. Moreover, a transition of magnetization mechanism took place along the increment of iron concentration which resulted in a larger permeability at high frequency. These findings provide a valuable reference for an in-depth understanding of spin spray deposition and an effective way to tune the performance of ferrite thin-film material.

Nanostructured Zn-Substituted Nickel Ferrite Thin Films: CMOS-Compatible Deposition and Excellent Soft Magnetic Properties

Nanostructured $\text{Ni}_x\text{Zn}_{1-x}$ Fe2O4 ( $x$ = 1, 0.5) films, about 1.5 µm thick on Si (100) substrates, were deposited using a low-temperature ( $A_{1g}$ vibration mode in Raman spectra of both films reveals a ‘‘far-from-equilibrium’’ crystallographic inversion induced by the MAS process. Its effect on the magnetic characteristics of the films is analyzed here. Both films exhibit in-plane ( $xy$ plane) isotropy with very low room-temperature coercivities, 25 Oe for NF and 35 Oe for ZNF, which is essential for high-frequency, soft magnetic applications. The presence of interparticular dipolar interaction in both films is confirmed from temperature-dependent magnetization measurements made under different dc bias fields. The CMOS-compatible ferrite processing and superparamagnetic Ni-ferrite and NiZn-ferrite thin films presented here can meet upcoming technological needs in on-chip integrated passive devices.

Fabrication and magnetic properties of Sol-Gel derived NiZn ferrite thin films for microwave applications

Fabrication and magnetic properties of Sol-Gel derived NiZn ferrite thin films for microwave applications

Microstructure and magnetic properties of Ni-Zn ferrite thin film synthesized using sol-gel and spin-coating technique

The nanocrystalline Ni-Zn ferrite thin film with the chemical formula Ni0.3Zn0.7Fe2O4 were deposited on glass substrate using sol-gel synthesis of metal nitrate aqueous solutions and spin-coating technique. Thin films of nickel-zinc ferrite have been prepared using spin-coating technique onto the ITO glass substrates. As-deposited films are annealed at 400, 500, 600 and 700 °C for 1 h. The Ni-Zn ferrite thin film with crystallite size of 20 nm has been successfully synthesized. The thickness of deposited films was below 300 nm and crystallite size was below 20 nm. The X-ray diffraction (XRD) analysis found the Ni-Zn thin films nanoferrite has a spinel cubic structure and lattice parameter of Fd3m. The crystallinity of the prepared Ni-Zn ferrite films increases as increase substrate temperature of a film deposition. Microstructures and chemical analysis by scanning electron microscopy and energy-dispersive spectroscopy showed that nanosized nickel-zinc ferrite particles with a diameter of 18.6 to 41.3 nm exist in the thin film. Magnetic properties of the Ni-Zn films have been characterised at room temperature, whereas the saturation magnetization M s. of the Ni-Zn films increase with increasing grain sizes. Maximum saturation magnetization M s. and coercivity H c are 3.42 emu/g and 16.54 Oe for thin films annealed at 500 and 700 °C, respectively. The M s. of the films shows a trend increasing and the H c value decreasing as increase the annealed temperature and the grain size of the Ni-Zn ferrite thin films. The conductivity decreases with increasing annealed temperature. It has been shown that the DC resistivity, saturation magnetization and coercivity of deposited films are influenced by annealing temperatures. The magnetic properties of Ni-Zn thin film with grain size of 18.6–41.3 nm shown a superparamagnetic behaviour were observed.

Dynamic magnetization of NiZn ferrite doped FeSiAl thin films fabricated by oblique sputtering

In this study, we comprehensively investigate the dynamic magnetic properties of FeSiAl-NiZnFeO thin films prepared by the oblique deposition method via a shorted microstrip perturbation technique. For the films with higher oblique angle and NiZn ferrite doping amount, there are two ferromagnetic resonance peaks observed in the permeability spectra, and both of the two peaks originate from FeSiAl. Furthermore, the magnetic anisotropy field HK of the ferromagnetic resonance peak at higher frequency is enhanced with increasing doping amount, which is interpreted in terms of the contribution of reinforced stress-induced anisotropy and shape anisotropy brought about by doping elements and oblique sputtering method. In addition, the thermal stability of the ferromagnetic resonance frequency fFMR of FeSiAl-NiZnFeO films with oblique angles of 35° and 45° with respect to temperature ranging from 300K to 420K is deteriorated with increasing ferrite doping amount, which is mainly ascribed to the influence of pair-ordering anisotropy and/or the reduction of the FeSiAl grain size.

Optical Properties of Spin-Deposited Nanocrystalline Ni-Zn Ferrite Thin Films Processed by Sol-Gel

Nano crystalline Zn-substituted Ni ferrite films with compositions of Ni1−xZnxFe2O4 (x = 0.25, 0.50, 0.75) were synthesized by sol–gel spin coating method. The synthesized films were characterized for their structural, morphology, optical, electric, and magnetic properties using x-ray diffraction, scanning electron microscope, UV-Vis spectrometer, two probe resistivity, and vibrating sample magnetometer techniques, respectively. The corresponding results indicate that zinc content has significant effect on physical, magnetic, and optical properties of the ferrite. X-ray diffraction studies of thin films showed that the samples have pure cubic spinel phase. The crystallite size is of the nanoparticles estimated using Debey-Scherrer’s method was found to be in the range of 10.27 to 14.97 nm. The lattice parameter was found to be increased from 8.35 to 8.40 A with increasing Zn2+ contents. The morphology of the thin films depicted the formation of well-developed nano-sized clusters with homogeneous and agglomerated. The optical absorption seen to be affected due to the presence of Zn in Ni-Zn ferrite thin films. Ni-Zn ferrite thin films possess small coercivity and remnant magnetization, which indicates the soft magnetic nature of the material. Electrical resistivity of the films decreases with increasing temperature, suggesting the semiconducting nature of the samples.

Influence of the interface on the magnetic properties of NiZn ferrite thin films treated by proton irradiation

In order to systematically investigate the influence of the interface on the magnetic properties, polycrystalline NiZn ferrite thin films were irradiated with 60keV proton in the dose range from 5×1012 to 5×1016ions/cm2. A non-destructive approach by proton irradiation was found to finely adjust the magnetic properties of polycrystalline NiZn ferrite thin films such as coercivity, perpendicular magnetic anisotropy as well as the effective g value. The coercivity is about 725Oe for high proton dose ferrite, which is twice larger than the unirradiated one. The ferromagnetic resonance measurements indicated that perpendicular magnetic anisotropy and the effective g value increase with the irradiation dose. Our finding indicates that all modifications of these magnetic properties were associated with the change of interface due to the diffusion and the stress induced by proton irradiation. The change of the effective g value is a result of lattice expansion and the decrease of the magnetic dipole interaction between the columnar grains. This work provides a feasible way to tailor the magnetic properties of thin films by ion irradiation and promotes investigations for the stability of magnetic thin film devices in space or unclear radiation environments.

Effect of experiment parameters on the structure and magnetic properties of NiZn-ferrite films

NiZn-ferrite thin films were deposited by radio frequency magnetron sputtering. The effects of sputtering pressure, substrate temperature, and annealing temperature on the structure and magnetic properties of the NiZn-ferrite thin films were investigated. The results revealed that the lower sputtering pressure was beneficial for the crystallization and grain growth of the NiZn-ferrite films, and the saturation magnetization and coercivity of the films monotonously decreased with increasing the sputtering pressure. Moreover, it was also suggested that a higher substrate temperature could improve the crystallinity and saturation magnetization of the thin films. Additionally, the saturation magnetization monotonously increased with increasing the annealing temperature, while the coercivity exhibited a minimum at an annealing temperature of about 600 °C. The change of saturation magnetization and coercivity as a function of sputtering pressure, substrate temperature and annealing temperature could be attributed to the varied crystallinity, grain size, cation distribution and the intrinsic stress of the films.

Growth behavior and RF/microwave properties of low temperature spin-sprayed NiZn ferrite

In our experiment, the influence of growth parameters of the spin-spray technique upon the microstructure and magnetic/microwave properties of NiZn spinel ferrite thin film was studied. By varying the pH value of precursor and oxidizer, the microstructure of NiZn ferrite thin film can be manipulated, further, bringing varying magnetic/microwave properties. High permeability μr′ > 200 at 0.5 GHz with low loss tanδm ~0.027 at 3–5 GHz range was achieved at precursor pH value of 4.6 and oxidizer pH value of 9.6. These magnetic/microwave properties are ideal for GHz range microwave application, for example, inductors, antennas, and electromagnetic interference suppression.

Effect of zinc doping on the structural and magnetic properties of nickel ferrite thin films fabricated by pulsed laser deposition technique

Abstract Zinc, as known as non-magnetic element, has been doped into nickel ferrite under thin film form to modify its structural and magnetic properties. Laser ablated Ni 1− x Zn x Fe 2 O 4 (0.0≤ x ≤0.5) thin films grown on R-cut Al 2 O 3 (0001) substrates using pulsed laser deposition (PLD) technique are single phase with (l l l) orientation, and they are strongly room temperature ferromagnetic. Compared to other Ni–Zn ferrite thin films we observed the enhancement in coercivity H c . Higher H c thin films can be used as potential candidates for modern miniaturization of electronic devices.

Numerical analysis of dominant loss parameters of ferrite thin films for conduction noise absorption in microstrip lines

The dominant power loss mechanism from conduction noise in a microstrip line was verified by investigating the effects of electrical conductivity and magnetic loss on noise reflection and transmission, and of power absorption in thin film absorbers (Ni-Zn ferrite thin film with high electrical resistivity, and electrically conductive ITO and Fe3O4 films). Using a simulation model of a microstrip line attached by thin films, the S parameters and power absorption were calculated for the frequency range from 0.05 to 3 GHz. Even if the film has a large value of magnetic loss due to ferromagnetic resonance, it is predicted that power dissipation by magnetic loss would be quite small, as was predicted for the Ni-Zn ferrite films. For the conductive and magnetic Fe3O4 thin film with similar magnetic loss dispersion, the contribution of magnetic loss to total power loss is also quite small. The values of S11, S21, and power absorption were almost the same as that for conductive ITO thin film of which the electrical resistivity was on the same order as that of the Fe3O4 thin film. The simulation of power absorption by the hybrid structure of ITO/Ni-Zn ferrite and ITO/Fe3O4 also supports this conclusion.

The Structure and Magnetic Properties of NiZn-Ferrite Films Deposited by Magnetron Sputtering at Room Temperature

NiZn-ferrite thin films were deposited onto silicon and glass substrates by radio frequency magnetron sputtering at room temperature. The effects of the relative oxygen flow ratio on the structure and magnetic properties of the thin films were investigated. The study results reveal that the films deposited under higher relative oxygen flow ratio show a better crystallinity. Static magnetic measurement results indicated that the saturation magnetization of the films was greatly affected by the crystallinity, grain dimension, and cation distribution in the NiZn-ferrite films. The NiZn-ferrite thin films with a maximum saturation magnetization of 151 emucm-3, which is about 40% of the bulk NiZn ferrite, was obtained under relative oxygen flow ratio of 60%.

ChemInform Abstract: Microwave Magnetic Properties of Soft Magnetic Thin Films

AbstractReview: 35 refs.

Structure and static magnetic properties of Zr-substituted NiZn ferrite thin films synthesized by sol–gel process

Zr-substituted NiZn ferrite thin films, Ni0.5Zn0.5ZrxFe2−xO4 (0⩽x⩽0.2), were synthesized by sol–gel process. The structure and magnetic properties of Ni0.5Zn0.5ZrxFe2−xO4 ferrite thin films have been investigated. The diffraction peak shifted towards the lower angle and the lattice parameter increased with Zr substitution. The average grain size of Zr-substituted NiZn ferrtie thin films increased with Zr substitution. The saturation magnetization gradually increased with the increase of Zr substitution when x⩽0.10, and decreased when x>0.10. Meanwhile, the coercivity initially decreased with the increase of Zr substitution when x⩽0.10, and increased when x>0.10.

Grain growth kinetics and magnetic properties of NiZn ferrite thin films

This paper focuses on the grain growth kinetics described by tradition phenomenological rate equation through nonlinear fitting of grain sizes for Ni 0.5Zn 0.5Fe 2O 4 ferrite thin films. The grain growth exponent n, which matches with normal grain growth, equals to 2.43 at 600 °C, and the process is controlled by anomalous solute drag which effects on the grain boundary mobility. As the annealing temperature rises from 700 °C to 900 °C, correspondingly the n goes up from 3 to 4, indicating that volume diffusion happens. The activation energy for grain growth are 22.75, 42.52, 56.32 and 85.54 kJ/mol from 600 °C to 900 °C, respectively, they are much smaller than that of the NiZn ferrite bulk. The effects of annealing temperature on the magnetic properties, phase structure and microstructure are investigated. The coercivity of NiZn ferrite thin films is mainly discussed via stress model.

Numerical analysis on thickness effect of magnetic thin films on conduction noise absorption in microstrip line

Noise absorbing properties of two kinds of magnetic thin films (one is electrically conductive Co-Zr-O granular thin film and the other is Ni-Zn ferrite thin film with high electrical resistivity) are analyzed by the finite element method (FEM) with various film thicknesses. For the Ni-Zn ferrite film with high electrical resistivity (∼2 × 10 2 Ωm), a low reflection parameter (S11) value is predicted, and the value does not significantly change with increased film thickness up to 10 μm. However, the transmission parameter (S21) is reduced with increased film thickness due to increased power absorption by magnetic loss. For the Co-Zr-O thin films with low electrical resistivity (∼1.6 × 10−5 Ωm), however, reflection signal is increased with increased film thickness due to diminished sheet resistance of the thin film. Transmission loss is not very sensitive to the thickness of the conductive film. Large power absorption is, therefore, predicted for conductive film of smaller thickness. It is concluded that film thickness is an important control parameter for the achievement of a highly absorptive thin film with increased electrical conductivity.

Structure and magnetic properties of Co-substituted NiZn ferrite thin films synthesized by the sol–gel process

Co-substituted NiZn ferrite thin films, Ni0.5Zn0.5CoxFe2−xO4 (0≤x≤0.2), were synthesized by the sol–gel process. The structure and magnetic properties of Ni0.5Zn0.5CoxFe2−xO4 ferrite thin films have been investigated. The diffraction peak shifted towards the lower angle and the lattice parameter increased with Co substitution. There is little influence of Co substitution on the microstructure of NiZn ferrite thin films. The saturation magnetization gradually increases with the increase in Co substitution when x≤0.10, and decreases when x>0.10. Meanwhile, the coercivity initially decreases with the increase in Co substitution when x≤0.10, and increases when x>0.10.