The Influence of Doping with Transition Metal Ions on the Structure and Magnetic Properties of Zinc Oxide Thin Films (original) (raw)
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Key Engineering Materials, 2016
Zinc oxide thin films were deposited on glass substrate at a substrate temperature of 673K by spray pyrolysis method using different concentration of 0.0125M, 0.025M and 0.05M of Zinc acetate solutions. The effect of molar concentrations on structure, surface morphology and magnetic properties of ZnO films were investigated using x-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. All deposited films were polycrystalline in nature with hexagonal wurtzite structure having a preferential growth orientation along (101) plane. An improvement of crystallinity in the deposits with increasing concentration of sprayed solution was noticed. All deposit exhibit fibrous structure which increases with increase of precursor concentration solutions. At room temperature, all deposited films were shown diamagnetic character but when cooled to 5K, they have shown paramagnetic characteristics.
2014
In this study, Ni doped ZnO (Zn1-xNixO, x= 0.02, 0.04, 0.07) Diluted magnetic semiconductors (DMSs) thin films onto Si substrates by spin-coating method from a precursor solution containing zinc acetate dissolved in methanol. After deposition, these films were preheated at 3500C for five minute and then annealed at 5500C for three hour for crystallize. Scanning Electron microscopy (SEM) image shows the particle size with an average size of 250 nm. The analysis of X-ray diffraction (XRD) identified that the impurity phase is observed when the Ni content x reaches 0.07. With the increment of x, wurtzite structures degrade gradually. The magnetic properties are measured using Vibrating Sample Magnetometer (VSM) at room temperature; the Zn1-xNixO (x=0.07) thin film shows ferromagnetism. The magnetic moment depends on Ni concentration and increases continuously as Ni concentration increases.
Journal of Magnetism and Magnetic Materials, 2013
The presence of structural defects degrade the crystalline quality of ZnO:Mn thin films and affects the magneto-optical properties of ZnO:Mn thin films. The donor defects in ZnO, which are known to be the source of n-type conductivity in ZnO host matrix, play an important role in limiting the ferromagnetism to lower temperatures. A systematic study of structural, optical and magnetic properties was carried out with the primary focus on understanding the relationship between the defect concentration, material composition and ferromagnetic properties. Single phase ZnO:Mn thin films with wurtzite structure were grown under ambient argon-oxygen admixture to investigate the effect of stoichiometry and interstitial oxygen on magnetic properties. A consistent increase in crystallinity of ZnO:Mn thin films (without precipitation of Mn) with increasing argon-oxygen admixture gas pressure was observed. Extended near band edge (NBE) emission spectra with marked decrease in photoluminescence (PL) ratio in optical characterization revealed improved optical quality of ZnO:Mn thin films. Magnetic measurements revealed enhanced room temperature ferromagnetism (RTFM) in sample grown at optimum argonoxygen ambient pressure. The enhancement was directly related to maximal core level X-ray photoelectron spectroscopic peak of stoichiometric ZnO which, in turn, favors strong hybridization of Mn in the ZnO host matrix.
Investigation of the room temperature ferro-magnetism in transition metal-doped ZnO thin films
Applied Physics A, 2020
In the present work, we report the ferromagnetic (Fe, Ni) co-doped Zn 1-x-y Ni y Fe x O (y = 0.01 and x = 0.01, 0.03, 0.05) thin films fabricated through the RF magnetron sputtering on Silicon (400) substrate. Structural studies of prepared thin films through X-ray Diffraction (XRD) reveal the formation of a single-phased hexagonal structure of films. Atomic Force Microscopy (AFM) confirms the decrease in surface roughness with the increase in Fe doping. The optical band gap of the thin films analyzed through the UV-Vis spectroscopy suggests the appropriateness of prepared thin films to be utilized in optoelectronic devices. The magnetic study of these thin films confirmed the room temperature ferromagnetic (RTFM) behavior for prepared thin films. The observed magnetic behavior has been described in view of polaron percolation theory.
Structural and Magnetic Properties of Mn/Fe co-Doped ZnO Thin Films Prepared by Sol–Gel Technique
IEEE Transactions on Magnetics, 2014
Mn/Fe co-doped ZnO thin films are prepared by simple sol-gel and spin coating method. Five different sols with the change in concentration (1-5 wt%) of both Mn and Fe are synthesized. Molar ratio of Mn and Fe is kept constant, i.e., 1:1. Sols are spun onto glass and copper substrates by spin coating method followed by the post magnetic field annealing at 300°C for 1 h. Effect of Mn and Fe codoping on ferromagnetic properties of ZnO is reported in this paper. Structural and magnetic properties of as prepared and annealed samples are investigated by X-ray diffractometer (XRD) and vibrating sample magnetometer (VSM). Scanning electron microscope is used to study the surface morphology of co-doped films. XRD results show incorporation of Mn and Fe in the host lattice upto a dopant concentration of 4 wt%. However, small crystallites of Mn and Fe 2 O 3 are observed by increasing the dopant concentration to 5 wt%. VSM results indicate room temperature ferromagnetism in all samples without the presence of any secondary phases. Low value of shape anisotropy is observed in the case of Mn doped ZnO. However, no shape anisotropy is observed in the case of co-doped thin films. Moreover, Mn/Fe co-doped thin films show magnetic hysteresis equivalent to that of multilayered structure, indicating that such complex structures used in spintronic devices can be replaced by a single ZnO layer with codoping of Mn and Fe.
The effect of zinc doping on the structural and magnetic properties of Ni1−x Zn x Fe2O4
Journal of Materials Science, 2013
Nanoparticles of Ni 1-x Zn x Fe 2 O 4 (x = 0.0, 0.1, 0.3, 0.5, 0.7, and 1.0) were synthesized by the sol-gel autocombustion method using ethylenediamine tetra acetic acid as a complexion agent. The detailed analysis of X-ray diffraction revealed that the crystalline structure was cubic spinel and by increasing x, it underwent a phase transition from normal to inverse spinel. The crystal lattice constant was increased gradually with increasing zinc substitution from 0.8339 nm (x = 0.0) to 0.8443 nm (x = 1.0). Also, the average crystallite size, which is determined from Scherrer formula, was about 14-35 nm. The spinel phase formation was further monitored by the FTIR analysis. The vibration sample magnetometer data showed that by increasing Zn doping level up to x = 0.3, the magnetization was increased and it was decreased by further increase in x. This effect was discussed by metal cations distribution into the tetrahedral and octahedral sites. Also, the coercivity was decreased by increasing Zn content due to the decrease of magnetocrystalline anisotropy constant of the samples.
Journal of Alloys and Compounds, 2013
In this research, Zn 1Àx Mn x O (0 6 x 6 0.2) thin films were synthesized by sol-gel technique for ferromagnetic and paramagnetic responses at high and low temperatures. In this respect, the produced films were characterized through X-ray diffraction (XRD), scanning electron microscope (SEM), UV-vis spectrometer and superconducting quantum interference device (SQUID) magnetometer. Based on the characterizations and measurements, the influence of pH on the structural, optical and magnetic properties of a Zn 1Àx Mn x O thin films was scrutinized in detail. The analyzed results indicate that the films possess a good crystal quality and homogeneous, smooth surfaces with a pure hexagonal zincsite syn structure of ZnO without any Mn based phases. By increasing the Mn content, the films exhibited increase or decrease in both the c-axis lattice constant and fundamental band gap energy depending on their respective pH. It is clear that the Zn 1Àx Mn x O (x = 0.02 and 0.05) thin films prepared at pH of 4.6 exhibited both a ferromagnetic at high temperatures (100, 200, and 300 K) and a paramagnetic response at low temperature (5 K), whilst Zn 1Àx Mn x O (0.01 6 x 6 0.2) films prepared at pH value of 7.56 have paramagnetic behavior and antiferromagnetic contributions. The observed room temperature ferromagnetic behavior of the Zn 1Àx Mn x O (x = 0.02 and 0.05) thin films at pH of 4.6 may be related to the interaction between Mn doping and the oxygen vacancies, an oxygen-vacancy-stabilized metastable phase Mn 2Àx Zn x O 3Àd or clustering of Mn ions.
Structural and magnetic properties of chemically synthesized Fe doped ZnO
Journal of Applied Physics, 2009
We report on the synthesis of Fe-doped ZnO with nominal composition of Zn 0.99 Fe 0.01 O by using a coprecipitation method. X-ray diffraction and selective area electron diffraction studies reveal a single phase wurtzite crystal structure without any secondary phase. Field emission transmission electron microscopy measurements infer that Zn 0.99 Fe 0.01 O have nanorod-type microstructures. Magnetic hysteresis measurement performed at different temperatures show that Zn 0.99 Fe 0.01 O exhibits a weak ferromagnetic behavior at room temperature. A detailed investigation of the electronic and local structure using O K-, Fe L 3,2 near edge x-ray absorption fine structure suggests that Fe is substituting Zn in ZnO matrix and is in Fe 3+ state.
Structural; morphological; optical and magnetic properties of Mn doped ferromagnetic ZnO thin film
Applied Surface Science, 2012
The structural, optical and magnetic properties of the Zn 1-x Mn x O (0 < x < 0.05) thin films synthesized by sol-gel technique have been analyzed in the light of modification of the electronic structure and disorder developed in the samples due to Mn doping. The films are of single phase in nature and no formation of any secondary phase has been detected from structural analysis. Absence of magnetic impurity phase in these films confirmed from morphological study also. Increasing tendency of lattice parameters and unit cell volume has been observed with increasing Mn doping concentration. The incorporation of Mn 2+ ions introduces disorder in the system. That also leads to slight degradation in crystalline quality of the films with increasing doping. The grain size reduces with increase in Mn doping proportion. The band gaps shows red shift with doping and the width of localized states shows an increasing tendency with doping concentration. It is due to the formation of impurity band and trapping of Mn atoms, which leads to the generation of the defect states within the forbidden band. Photoluminescence (PL) spectra shows gradual decrease of intensity of exitonic and defect related peaks with increasing Mn doping. Defect mediated intrinsic ferromagnetism has been observed even at room temperature for 5at% Mn doped ZnO film. The strong presence of antiferromagnetic (AFM) interaction reduces the observed ferromagnetic moments.