Spinel Lattice Research Articles

Synthesis Techniques of Nickel Substituted Cobalt Ferrites – An Investigative Study Using Structural Data

Structural properties of nickel-substituted cobalt ferrite nano-particles Ni x Co 1-x Fe 2 O 4 (x=0.2,0.8) synthesized using two different methods, namely combustion and co-precipitation are studied. The structural parameters of Nickel-substituted Cobalt ferrite nano-particles confirm the formation of nano-sized particles of cubic spinel structure. Lattice parameters, density, particle size and inhomogeneity are determined while Attenuated total reflectance (ATR-IR) spectroscopy and scanning electron microscope images are studied. The ATR-IR spectra show transmission peaks, in the range around 600cm -1 and 400 cm -1 which respectively arise from tetrahedral and octahedral interstitial sites in the spinel lattice and found cationic exchanges between the lattices of these sites. The studies reveal that the sol–gel auto combustion method can be preferred to the co-precipitation method for producing single phase nano particles with smaller crystallite size

Effect of cation ratio on microstructure and optical absorbance of magnesium aluminate spinel

This work is pertaining to the synthesis of fine magnesium aluminate spinel (MgAl2O4) powders of varied trivalent:bivalent cation ratio along line of homogeneity of the solid solution (MgO. xAl2O3, x = 1, 1.25, 1.50, 1.75, and 2) via gel combustion method. Magnesium- and aluminum- nitrate were used as the oxidants in combustion reaction fuelled by urea in combination with stoichiometric formaldehyde solution acting as reductant. Synthesized powders were characterized in terms of microscopic analysis and optical absorbance measurements. The cation ratio, through a change in gel structure influences the nature of crystallization of the product, while on the other hand does not affect grain shapes and sizes. Distinct enhancement in both absorption intensity and the corresponding estimated energy band gap has been observed against increasing excess than stiochiometric alumina concentrations. Evaluated optical band gaps were widened in proportion to the Al: Mg ratio which may be attributed to Burstein-Moss effect in consequence of substitutional insertion of introduced Al3+ ions in spinel lattices.

Correlating the size and cation inversion factor in context of magnetic and optical behavior of CoFe2O4 nanoparticles.

Herein, the size dependent behavior of cobalt ferrite nanoparticles was investigated using synchrotron radiation based techniques. Scanning electron micrographs revealed the enhancement of particle/crystallite size with increase of annealing temperature. Moreover, the shape of these particles also changed with increase of crystallite size. Saturation magnetization increased with increase of crystallite size. The higher saturation magnetization for larger crystallite size nanoparticles was attributed to a cation distribution similar to that of bulk CoFe2O4. The optical band-gap of these nanoparticles decreased from 1.9 eV to 1.7 eV with increase of crystallite size. The enhancement of the optical band-gap for smaller crystallites was due to phenomena of optical confinement occurring in the nanoparticles. Fe L Co L-edge near edge extended X-ray absorption fine structure (NEXAFS) measurements showed that Fe and Co ions remain in the 3+ and 2+ state in these nanoparticles. The results obtained from Fe & Co K-edge X-ray absorption near edge structure (XANES)-imaging experiments further revealed that this oxidation state was possessed by even the crystallites. Extended X-ray absorption fine structure (EXAFS) measurements revealed distribution of Fe and Co ions among tetrahedral (A) and octahedral (B) sites of the spinel structure which corroborates the results obtained from Rietveld refinement of X-ray diffraction patterns (XRD). X-ray magnetic circular di-chroism (XMCD) measurements revealed negative exchange interaction among the ions situated in tetrahedral (A) and octahedral (B) sites. Theoretical and experimental calculated magnetic moments revealed the dominancy of size effects rather than the cation redistribution in the spinel lattice of CoFe2O4 nanoparticles.

Enhancement of red emission assigned to inversion defects in ZnAl2O4:Cr3+ hollow spheres

ZnAl2O4:Cr3+ hollow spheres composed of secondary nanoparticles with single spinel phase were fabricated using carbon templets. Monitoring the emission of 687 nm, two wide excitation bands attributed to the electrons of Cr3+ transiting from 4A2g (4F) → 4T1g (4F) and 4A2g (4F) → 4T2g (4F) were observed. The broad excitation band at about 397 nm was asymmetric and consisted of two peaks, indicating that there was a trigonal distortion existing in the lattices. The intensity of all emitting peaks revealed sharp increasing trend with the sintering temperature increase, and the intensity of emission at 698 nm assigned to inversion defects was more intense than that of emission at 687 nm assigned to octahedral Cr3+ ions in the undistorted spinel lattice. The samples with higher synthesized temperature revealed longer decay time, and the relative weightage of shorter decay time component decreased with the increase of sintering temperature, indicating that the surface defects decreased.

Oxidation of lean methane over cobalt catalysts supported on ceria/alumina

Cobalt (30 %wt.) oxide catalysts supported over ceria-modified (3–18 %wt.) alumina supports were examined for the combustion of lean methane. The prepared samples were characterised by wavelength dispersive X-ray fluorescence, N2 physisorption, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, temperature-programmed reduction with hydrogen and temperature-programmed reaction with methane. A significant enhancement of the activity was evidenced with respect to the catalyst supported over bare alumina, with an optimal cerium loading of 12 %wt. and a resultant T50 value of 480 °C. The ceria modification was found to induce a dual positive effect on the performance of the cobalt catalysts. On one hand, it acted as a physical barrier between deposited cobalt and alumina, thus inhibiting the cobalt-alumina interaction and the subsequent cobalt aluminate formation. On the other hand, the insertion of cerium ions in the spinel lattice led to a distortion of the structure that in turn resulted in an enhanced mobility of the oxygen species. The optimised catalyst exhibited a relatively good thermal stability for prolonged reaction time intervals (150 h) under dry conditions. The presence of water vapour markedly affected the catalytic performance although this negative effect was partially reversible.

Characterization of the In Situ‐Formed Oxide Layer at the Steel Melt/Carbon‐Bonded Alumina Interface

The surface structure development of the in situ‐formed oxide layer on carbon‐bonded alumina refractory samples immersed in liquid 42CrMo4 steel at a temperature of 1650 °C is studied. The surface morphology is characterized using areal parameters such as the developed interfacial area ratio Sdr, the texture aspect ration Str, the arithmetic mean peak curvature Spc, the density of peaks Spd, and the maximum height Sz defined in ISO 25178‐2:2012 and on the basis of own defined parameters using laser‐optical measured line profiles of the surface's height. The development of the surface morphology is found to be independent of the oxygen content of the steel melt at immersion time. The formed crystal structures are based on alumina and an (Al, Fe, Mg, Mn)‐containing spinel. The spinel's lattice parameters are found to vary between 8.0367 and 8.1194 Å corresponding to oxygen contents of the steel melt between 30 and 85 ppm.

Synthesis, characterization of Mg/Mn substituted Ni-Zn ferrites and mechanism of their visible light photo catalysis of Methylene Blue and Rhodamine B dyes under magnetic influence

Rare earth doped spinel ferrites belonging to the series Ni0.6Zn0.2Me0.2GdxFe2-xO4 (where Me = Mg/Mn, x = 0/0.06) were synthesized by sol-gel method. The characterizations of the prepared samples were performed using X-rayDiffraction (XRD), High Resolution Transmission Electron (HRTEM) Microscopy, Vibrating Sample Magnetometry (VSM), X-ray Photoelectron Spectroscopy (XPS) and Open aperture z-scan technique. The XRD patterns confirm the crystallization of the ferrites in cubic form with spinel structure. The average crystallite size calculated using Debye–Scherrer’s equation is in 10–20 nm range. The HRTEM images reveal the formation of spherically shaped agglomerated nanoparticles. The magnetic parameters such as remanence magnetization (Mr), coercivity (Hc) and saturation magnetization (Ms) were obtained from the hysteresis curves. The samples show better optical limiting parameters than reported which make them promising materials for non-linear applications requiring low limiting thresholds. Owing to their low band gaps ferrites can be efficiently used for the photo catalysis of organic dyes with visible solar energy which constitutes a major portion of sunlight. Ferrites have an added advantage by virtue of their spinel lattice which makes available extra catalytic sites. In the present work, the photocatalytic activity under visible sunlight irradiation was explored from the degradation of Methylene Blue (MB) and Rhodamine B (RhB) dyes. Higher photocatalytic efficiency was exhibited by magnesium containing samples. Near total decolouration of dye solution subjected to magnetic separation has not been reported before. The improvement in photocatalytic degradation efficiency is due to the adsorption followed by effective separation and prevention of photo generated electron-hole pair recombination for a longer period by these ferrites. To further aid the degradation, H2O2 was added as precursor to the reactive mixture which increases the formation of hydroxyl radical (OH·).

Structure-Function Correlation: Engineering High Quantum Yields in Down-Shifting Nanophosphors.

Lanthanides are routinely incorporated into quantum dots to act as down-shifting and up-converting phosphors in display and lighting applications due to their high photoluminescence quantum yields (PLQY). Recent efforts in the field have demonstrated that trivalent lanthanide, Ln(III), incorporated into ZnAl2O4 spinel nanocrystals can achieve PLQYs of 50% for down-shifting nanophosphors using earth abundant materials. The high PLQY is surprising as the Al(III) site in a spinel is centrosymmetric, which should lead to poor performance for these nanophosphors. However, spinels are prone to formation of an admixture of inverse and normal spinel lattices when the cation size ratio is not optimal. Such behavior can produce local cation disorder that can influence the phosphor performance. Herein, we describe the use of Tb(III) as an optical probe to evaluate the fractional population of the inverse and normal spinel structures within TbxZnAl2-xO4. The experimental data exhibits a Tb(III) concentration dependent change in the fractional population that results in a maximum PLQY of 37% with 3.56% Tb(III) incorporation. A decrease in the degree of inversion (cation disorder) leads to larger amounts of the cubic Fd3m phase resulting in the observed photoluminescence behavior. The correlation of NMR, pXRD, and optical methods provides direct insight into the high PLQY behavior for this class of nanophosphor.

Dependance of lanthanum ions on structural, magnetic and electrical of manganese based spinel nanoferrites

Lanthanum doped manganese spinel nanoferrites (MnLaXFe2-XO4) with X = 0.00, 0.02, 0.04, 0.06 and 0.08 were fabricated by sol-gel method. The cubic phase was confirmed by using X-ray diffraction technique. FESEM revealed that the prepared samples attain highly stable spherical morphology. Energy dispersive X-ray spectra confirm the presence of Manganese (Mn), Lanthanum (La), Iron oxide (Fe) and oxygen (O) element in desired proportion. Ultra-violent diffuse reflectance spectroscopy shows that absorbance spectra were inversely proportional to band gap energy. Room temperature magnetic hysteresis curves expose the ferromagnetic behavior with decreases of saturation (Ms) and increases of coercivity (Oe). The origin of ferromagnetism in La3+ doped manganese nanoferrites were elaborated with reverence to the allocation of Mn2+ and Fe3+ ion within the spinel lattice. An impedance spectroscopy of the samples were analyzed in the frequency ranges from 0 to 7 MHz at room temperature reveals the resistance of the grains and grain boundary were found to increase with La3+ ion. The dielectric constant and loss tangent decreases with increases of frequency. The obtained results confirm that the prepared samples were useful for better radiation-absorption properties.

57Fe Mössbauer study of high-yield CuFe2O4 nanoparticles produced by the levitation-jet aerosol technique with post-synthesis annealing

Pseudo-spherical cubic-shaped nanoparticles of spinel ferrite CuFe2O4 have been prepared using a two-stage process. At first, an evaporation of levitating copper–iron drop into mix of helium–air gas flow took place, which resulting in copper ferrite-based powders. Then, such powders were additionally oxidized trough the heterogeneous auto-wave combustion in open air. We studied the effect of performing the synthesis in either an air or a helium environment on the phase composition of nanoparticles, and how the use of a post-synthesis annealing step modifies this, using room temperature 57Fe Mossbauer spectroscopy. By applying this technique, we are able to distinguish between the normal (non-magnetic) and inverse cubic (magnetic) phases of CuFe2O4, which is usually inaccessible using X-ray diffraction, as well as quantifying their relative amounts within each sample. Furthermore, we have been able to quantify trace amounts of the tetragonal CuFe2O4, phases that are typically obscured by line-broadening effects within our X-ray diffraction data, which indicates that annealing using a propane flame can also cause a cubic to tetragonal distortion in the crystal structure of the spinel lattice. Finally, by combining our Mossbauer parameters, which are sensitive to the Fe-containing phases only, with X-ray diffraction data, which are sensitive to all phases, we report on the full phase composition for the first time for nanoparticles produced via this synthesis route.

Steam reforming of ethylene over manganese-chromium spinel oxides

A series of Mn-Cr-O spinel catalysts of different stoichiometry was synthesized using a sol-gel method and characterized using X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, N2 and H2O adsorption, and H2-temperature programmed reduction. The introduction of extra Mn to stoichiometric MnCr2O4 led to Mn3+ substitution in the spinel lattice of Mn1.5Cr1.5O4 whereas excess Cr in Mn0.5Cr2.5O4 formed Cr2O3. Ethylene steam reforming at atmospheric total pressure and 873 K over the Mn-Cr-O spinel catalysts was nearly first order in ethylene, negative order in water and zero order in excess dihydrogen. The reaction kinetics were consistent with a Mars-van Krevelen type mechanism. Whereas Cr2O3 was nearly inactive for ethylene steam reforming, Mn3O4 was substantially more active than the spinel catalysts, but Mn3O4 deactivated significantly upon in situ reduction to MnO. The spinel catalysts were therefore more active and structurally stable for ethylene steam reforming than either of the pure metal oxides.

Influence of Ce3+ substitution on the structural, electrical and magnetic properties of Zn0.5Mn0.43Cd0.07Fe2O4 spinel ferrites

In this paper, the effect of Ce3+ ions addition on the microstructure, electrical and magnetic behaviour of Cadmium doped Mn–Zn ferrites was investigated. A series having composition Zn0·5Mn0·43Cd0·07Fe2-yCeyO4 (y = 0.0–0.7) was synthesized by wet chemical route. X-Ray Diffraction (XRD) analysis showed that prepared particles having size in nano-regime having cubic spinel structure with preferred (311) plane. Weakening of (311) plane intensity and emergence of secondary phase with Ce3+ ion concentration verified the substitution of Ce3+ ions in the spinel lattice of ferrite. The crystallite size varied between 46.4 and 67 nm as the concentration of Ce3+ ions increased from x = 0.0–0.7. Temperature and composition dependent electrical resistivity and activation energy values were calculated by current-voltage (I–V) characteristics in the temperature range 423–823 K by two probe method. It was observed that DC Resistivity and activation energy of synthesized nanoparticle ranges between109 to ~1010 Ohm cm and 11.78–2.56 eV respectively with increasing the concentration of Ce3+ ions. MH curves of prepared samples showed the paramagnetic nature of spinel feerites. The reported data suggested that these particles promising candidates for high-frequency applications.

Sc-doping induced cation-disorder in LiNi0.5Mn1.5O4 spinel leading to improved electrochemical performance as cathode in lithium ion batteries

Ni/Mn disordered LiNi0.5Mn1.5O4 spinel is the most promising cathode material for lithium ion batteries due to its high energy and power densities. However, the Ni/Mn disorder coupled with high Mn3+ content and concomitant formations of NiO/LiyNi1-yO impurities deteriorate its electrochemical performances. To overcome this issue, Sc-doped disordered spinel LiNi0.5Mn1.44Sc0.06O4 without NiO/LiyNi1-yO impurities has been synthesized. Infrared spectroscopy, magnetic measurements and cyclic voltammetry results reveal the increase in Ni/Mn disordering of LiNi0.5Mn1.44Sc0.06O4 than pristine spinel which decreases the charge transfer resistance and enhances the electrochemical performances. The XPS spectrum of LiNi0.5Mn1.44Sc0.06O4 exhibits Sc2p3/2 (402.3 eV) and Sc2p1/2 (406.5 eV) bands confirming the presence of Sc3+ in the spinel lattice. Sc-doped spinel delivers an initial discharge capacity 131 mAhg−1 with 88% columbic efficiency at 0.1C rate. Under similar condition, the undoped spinel yields only 123 mAhg−1 with 81% columbic efficiency. In addition, cycling stability of the doped spinel has increased dramatically with increase in the C-rate. At 5C, it exhibits a specific capacity of 102 mAhg−1 with 98% capacity retention even after 1000 cycles. Furthermore, it demonstrates excellent rate capability due to enhanced lithium-ion diffusion kinetics. The improved performance of the spinel can be attributed to the stabilization of the cation disordered structure. Thus, the Sc-doped spinel could be a potential cathode material for lithium ion batteries for electric vehicle applications.

Production of hydrogen by methane dry reforming over ruthenium-nickel based catalysts deposited on Al2O3, MgAl2O4, and YSZ

In this work, monometallic (1 wt% of Ru or 5 wt% of Ni) and bimetallic catalysts (1 wt% Ru-5 wt.% Ni) deposited on alumina (Al2O3), magnesium aluminate spinel (MgAl2O4), and yttria-stabilized zirconia (YSZ) were prepared by wet impregnation. The synthesis method of MgAl2O4 was optimized and a well crystallized phase with high specific surface area was obtained by using wet impregnation, as a simple and low cost route, at 800 °C for 2 h.The catalytic activity was compared at atmospheric pressure and 750 °C toward methane dry reforming (DRM) reaction with a molar ratio CH4/CO2 = 1/1 and a Weight Hourly Space Velocity (WHSV) of 60.000 mL g−1.h−1.Catalytic activity classification was obtained as the following: Ni/MgAl2O4 > Ru-Ni/Al2O3 > Ru-Ni/MgAl2O4 > Ru-Ni/YSZ > Ni/Al2O3 > Ni/YSZ > Ru/Al2O3 > Ru/YSZ » Ru/MgAl2O4. Between the different catalysts, 5 wt% Ni/MgAl2O4 catalyst exhibited excellent catalytic activity for DRM. Furthermore, this catalyst was found to be very stable without any deactivation after 50 h under reacting mixture with a low carbon formation rate (3.58 mgC/gcat/h). Such superior activity and stability of MgAl2O4 supported Ni catalyst is consistent with characterization results from BET, XRD, TPR, CO-pulse chemisorption and CHNS analysis. It can be due to a strong interaction between Ni and MgAl2O4 leading to the incorporation of Ni into the spinel lattice and the formation of oxygen vacancies offering a benefit for DRM reaction.Furthermore, it seems that the addition of ruthenium onto Ni/MgAl2O4 decreases the interaction between Ni and the spinel leading to a decrease in the catalyst performance. On the other side, the addition of ruthenium on Ni/Al2O3 leads to an increase in the catalyst stability and efficiency by inhibiting the formation of poorly active phase NiAl2O4 already observed in TPR.

Effect of Pr3+-doping on the structural, elastic and magnetic properties of Mn–Zn ferrite nanoparticles prepared by solution combustion synthesis method

Abstract Ferrite nanoparticles are currently used for important applications in the field of medical particularly, target-directed medicine and cancer treatment. Keeping this in mind, in the present work we prepared Pr3+ doped Mn0.5Zn0.5Fe2O4 nanoparticles by combustion route. The crystallinity and structure were confirmed by XRD. The Elastic properties are estimated by using FTIR data and reveals that variation of elastic constants has been interpreted in terms of strength of inter-atomic bonding and electronic configuration of the cations involved in the samples. Further variation of stiffness constants, Poison's ratio, elastic constants, longitudinal and transverse wave velocity is studied with respect to Pr3+content. Significant influence is observed in elastic values due to the addition of larger ionic radii of Pr3+ in spinel lattice. The intensity of magnetization, remanence, and coercivity was found to be decreasing with increasing Pr3+ concentration. Hence these samples are potential candidates for medical applications i.e. magnetic resonance imaging.

Structural, electrical and magnetic properties of cobalt ferrite with Nd3+ doping

A systematic study on the influence of Nd3+ substitution on structural, magnetic and electrical properties of cobalt ferrite nanopowders obtained by sol–gel auto-combustion route was reported. The formation of spinel phase was confirmed by X-ray diffraction (XRD) data, and percolation limit of Nd3+ into the spinel lattice was also observed. Fourier transform infrared spectroscopy (FTIR) bands observed ≈ 580 and ≈ 390 cm−1 support the presence of Fe3+ at A and B sites in the spinel lattice. The variation in microstructure was investigated by scanning electron microscopy (SEM), and the average grain size varies from 5.3 to 3.3 µm. The substitution of Nd3+ significantly affects the formation of pores and grain size of cobalt ferrite. Room-temperature saturation magnetization and coercivity decrease from 60 to 30 mA·m2·g−1 and 19.9–17.8 mT, respectively, with Nd3+ substitution increasing. These decreases in magnetic properties are explained based on the presence of non-magnetic nature of Nd3+ concentration and the dilution of super-exchange interaction in the spinel lattice. The room-temperature direct-current electrical resistivity increases with Nd3+ concentration increasing, which is due to the unavailability of Fe2+ at octahedral B sites.

Surficial Structure Retention Mechanism for LiNi0.8Co0.15Al0.05O2 in a Full Gradient Cathode.

A LiNi0.8Co0.15Al0.05O2 (NCA) solid battery was assembled by coupling an NCA cathode with a polyvinylidene fluoride (PVDF)/Li6.75La3Z1.75Ta0.25O12 (LLZTO) composite polymer electrolyte and a Li anode. A NiO-like phase transition is regarded as the reason for interface impedance, which leads to drastic capacity fading during cycling. A gradient cathode with excessive addition of Li6.75La3Zr1.75Ta0.25O12 was fabricated at the cathode/electrolyte interface to overcome the increased impedance. Using high-resolution transmission electron microscopy and electron energy loss spectra, the formation of a unique localized cation migration (LCM) region was confirmed on the NCA surface. The formation of an LCM region hindered further distortion and enhanced the capacity retention of the spinel lattice.

Spectroscopic investigation on tetrahedral Co2+ in thin-film CoFe2O4

CoFe2O4 has been attracting attention for its ferrimagnetism applicable to spin transfer, resonance imaging, drug delivery etc. CoFe2O4 thin films were synthesized on Si(100) substrates by using a sol–gel deposition process. The CoFe2O4 specimen produced by post-annealing in air at 800 °C showed flat surface and polycrystalline grains with no secondary phase. The specimen exhibited magnetic hysteresis curve with magnetization up to 415 emu/cm3 and coercivity of 1.7 kOe. Such a large magnetization implies migration of a number of Co2+ ions from octahedral to tetrahedral sites of the spinel lattice. The distribution of Co2+ ions among tetrahedral and octahedral sites of CoFe2O4 was estimated by curve-fitting analysis on the Raman scattering spectrum of the specimen. The result suggests 30% of the Co2+ ions residing in the tetrahedral sites. The coexistence of Co2+ ions in both tetrahedral and octahedral sites of CoFe2O4 was also detectable by using Co 2p X-ray photoelectron spectroscopy.

Effect of Zn–Cr substitution on the structural, magnetic and electrical properties of magnesium ferrite materials

The ferrite having the general chemical formula Mg1-xZnxFe2-xCrxO4 (x = 0.0, 0.1, 0.3, 0.5 and 0.7) prepared by the solid state technique. The XRD analysis depicted the presence of single phase cubic spinel structure. They showed an increasing trend of lattice parameter with the expansion of the spinel lattice which resulted from the partial incorporation of larger radii. The FT-IR absorption bands are observed at 590 and 430 cm−1 for tetrahedral and octahedral location. These bands are shifting toward 604.7 and 474.15 cm−1 for Zn–Cr substitution due to the change in Me–O covalence. DC electrical resistivity has found to show the highest magnitude 107 Ω cm at x = 0.1, decreases with further increase in content. The hysteresis curves measured at 300 K demonstrate the coercivity and it varies from 146.33 to 9.427 Oe for increasing the content which confirms decreasing the grain size as well as soft ferrimagnetic material.

Design of zinc ferrite thin films with excess tetrahedrally coordinated Fe3+ ions and their magnetic interactions

In the present work, zinc ferrite thin films on glass substrates were grown using radio-frequency sputtering method in oxygen environment at base pressure of 2 × 10−6 Torr. As-grown films were annealed at 200 °C for 1, 3 and 5 h. X-ray diffraction study envisaged the existence of peaks corresponding to (311) and (440) planes of cubic spinel structure. Both the lattice parameter and crystallite size increased with annealing time leading to crystal perfection with annealing time. Fourier transform infrared spectroscopic study showed presence of bands corresponding to metal-oxygen vibrations in the spinel lattice. Fe K-edge extended X-ray absorption fine structure (EXAFS) measurements revealed that the tetrahedral site occupancy of Fe3+ ions are 1.2 for as-grown zinc ferrite thin film. This occupancy is 1.18, 1.12 and 1.09 for annealing times of 1, 3 and 5 h, respectively. These observations were supported by Zn K-edge EXAFS investigations. X-ray magnetic circular dichroism measurements performed for these films show negative exchange interaction among the Fe3+ ions situtated at different sites. Thus, zinc ferrite thin films having excess occupancy at tetrahedral site was successfully designed on glass substrate.