Papers by Keyword: ZnFe₂O₄

Abstract: This study aims to determine the magnetic properties and structural properties of zinc ferrite (ZnFe₂O₄) material with the sonochemichal synthesis method. The sonochemichal method was obtained by sonication lasting for 30 minutes with the addition of 100 ml of 10 M NaOH. ZnFe₂O₄ material was sintered with temperature variations of 950°C, 1050°C, and 1150°C with a holding time of 2 hours. Phase identification revealed that the cubic phase structure of zinc ferrite is franklinite and also obtained crystal size results with values ​​of 70.58 – 84.71 nm. Morphological identification revealed that the ZnFe₂O₄ material had an irregular cubic shape and the highest agglomeration was at ZnFe₂O₄ temperature of 950°C. Identification of functional groups using FTIR characterization resulted in the wavelength range of 400-600cm^-1 having basic lattices of Fe-O and Zn-O which occupy tetrahedral and octahedral positions, respectively. Magnetic identification uses VSM characterization which results that the sample is softmagnetic and gets several Mr, Ms, and Hc values. ZnFe₂O₄ with a sintering temperature of 1150°C in this study has the potential to be used as a microwave device.

Abstract: ZnFe₂O₄ nanomaterials were prepared using a solid-state reaction method using high energy milling (750 rpm) for 30 hours and calcined at 1000°C for 5 hours. The characterizations used include XRD, SEM, VSM, and VNA. The measurement results show that the sample has a single phase with a cubic structure. The surface morphology of heterogeneous samples with a particle size of 250-400 nm shows magnetic performance with Ms 2.38 emu/g and Hc 11.29 kOe. The sample also can absorb electromagnetic waves in the frequency range of 2-18 GHz with a minimum RL value of ~-18.79 dB at a frequency of 3.66 GHz, while RL ~-13.32 dB has a bandwidth of 0.9 GHz.

Abstract: Electroceramic with high magnetic properties such as ZnFe₂O₄ is widely used in many electronic device applications. One of the major drawbacks of electroceramic is the difficulty in molding and processing into desired shapes due to its brittle nature. Flexible electroceramic with the superior process and mold abilities can be made by mixing magnetic ceramic with a flexible matrix, for instance, rubber. In this present study, the aims were to produce ZnFe₂O₄ loaded epoxidized natural rubber (ENR 25) as well as to determine its electrical and curing properties. The magnetic ceramic of ZnFe₂O₄ was blended with ENR 25 at different loadings varying from 0 to 120 parts per hundred of rubber (phr) in an interval of 20. The properties of produced composites include scorch time, cure time, torque and dielectric properties were characterised. The results demonstrated that the increase of ZnFe₂O₄ concentration in ENR 25 leads to a significant increase in the dielectric constant from 4.94 to 5.62 at 1.15 MHz, and decrease in the dielectric loss curves of the composites start from 0.0827 to 0.0586. Furthermore, the results of curing property studies exhibited an increasing pattern of the composite torques, starting from 1.43 to 1.76 dN.m.

Abstract: Nanocrystalline spinel zinc ferrite ZnFe₂O₄ thin film has been studied and synthesized via the electrodeposition-anodization process. Electrodeposited ZnFe₂ alloys were obtained from aqueous sulphate bath. The resulted alloys were electrochemically oxidized in strong alkaline solution (1 M KOH) at room temperature to the analogous hydroxides. The electroanodized ZnFe₂ alloy film was annealed in air at 400 °C for 2 h to get the required zinc ferrite. The electrochemical factors controlling of the electrodeposition of ZnFe₂ alloys such as the bath temperature, agitation, the current density were studied and optimized. The crystal structure, crystal size and microstructure of the produced ferrites were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The deposited film was mainly composed of ZnFe₂O₄ based on XRD studies. The produced film had a spinel structure and the crystallite size was 4.9 nm. SEM micrograph of the resulted zinc ferrite particles shows compact crystallites shapes and agglomerated chains with smallest semicircular particles like morphology.

Abstract: Zinc ferrites (ZnFe₂O₄) nanoparticles were successfully prepared by the simple co-precipitation method. The effects of calcination temperature and the amount of surfactant on the microstructure of zinc ferrite products were studied. The products were characterized with X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and UV-Vis diffuse reflectance spectroscopy (DRS). The XRD results confirmed the formation of a cubic spinel structure in all samples. The SEM results revealed that surfactant molecules play a crucial role to control the microstructure of the samples. All samples showed extended absorptions in the visible region. The photocatalytic results indicated that ZnFe₂O₄ enhanced the photocatalytic activity with increased calcination temperature. In addition, the ZnFe₂O₄ prepared by addition of high concentrations of surfactant gave the highest photocatalytic activity. The synthesized ZnFe₂O₄ can be recovered by applying an external magnetic field.

Abstract: Electrochemical sensors based on tubular yttria-stabilized zerconia (YSZ) with the spinel-type oxide as a sensing-electrode (SE), which is prepared by sol-gel method, were fabricated and examined for NO₂ detection in the temperature range 450~500°C. The results show that ZnFe₂O₄, shows extreme sensitivity to NO₂. The EMF varies linearly as a function of the concentration of NO₂ (0 ~ 463 ppm) at 500 °C.

Abstract: The ZnFe₂O₄ nanometer powders were prepared by EDTA sol-gel method. The samples were characterized by DTA, FT-IR, XRD techniques. The preparation process, the best heat-treatment temperature and the electrochemical performance had been studied. The results show that the spherical nanometer powders can be obtained and the best heat-treatment temperature is 900°C. The particle size is about 10nm and Ea is 0.88 eV.

Abstract: The nanoscale magnetic composite powders BaFe12O19-ZnFe2O4 were prepared by two-step citrate sol-gel, with analytically pure Fe(NO3)3、Zn(NO3)2 and Ba(NO3)2 as the main materials. The XRD, TEM and VSM were used to analyze the structure, feature and magnetic property of the nano-powder. The results show that the same presoma is calcined in 600°C、650°Cand 700°C obtained BaFe12O19-ZnFe2O4，XRD display for both pure phase, do not contain any mixed phase。The higher the temperature, the content of magnetoplumbite phase increased, corresponding the content of spinel phase low。By hysteresis loop of composite powde BaFe12O19- ZnFe2O4 can see, simple substance BaFe12O19 magnetoplumbite phase has the wasp waist shaped hysteresis loop，simple substance ZnFe2O4 spinel phase has superparamagnetism，but the nanoscale composite powders BaFe12O19-ZnFe2O4 has rectangular hysteresis loop。

Abstract: ZnFe2O4 powders are synthesized by solid phase method and used to make sensing electrode. Electrochemical cells are prepared with an oxygen ionic conductor (Y2O3-stabilized ZrO2: YSZ) with a semiconducting oxide (ZnFe2O4) electrode. Pt is used as the counter electrode. The devices shows promising NO2 sensing performance at 450, 550 and 650oC.The electromotive force (EMF) value of the ZnFe2O4/YSZ/Pt sensor increases with the increasing of concentrations of NO2 in N2.

Abstract: The effects of sintering temperature on the structural and electrical transport properties of nanocrystalline zinc ferrites are reported. The zinc ferrites were prepared by WOWS sol-gel synthesis route. The prepared sample was sintered at temperatures 500°C, 700°C and 900°C respectively for 2 h. X-ray Diffraction (XRD) technique was used to describe the structural properties. The crystallite size, lattice parameters and porosity of samples were measured from the analysis of XRD data. The average crystallite size for each sample was measured using the Scherrer formula by considering the most intense (3 1 1) peak. The dielectric constant (ε), dielectric loss tangent (tan ) and AC electrical conductivity of nanocrystalline Zn ferrites are investigated as a function of frequency and sintering temperature. All the electrical properties are explained in accordance with MaxwellWagner model and Koops phenomenological theory.