Fe-doped ZnO Research Articles

Iron(II)-induced defect luminescence and deconvolution of ferromagnetic and paramagnetic behaviour in Zn(1-x)FexO (x = 0.01, 0.03, 0.05) nanoparticles

Zn(1-x)FexO (x = 0.00, 0.01, 0.03, 0.05) nanoparticles (NPs) were prepared by co-precipitation method and the wurtzite phase was confirmed by x-ray diffraction (XRD). The average crystallite size changes from 36 nm to 26 → 23→22 nm as the Fe-doping level varies from 0 to 1% → 3% → 5 % and the lattice strain increases concomitantly. The pristine ZnO NPs exhibit well-defined peak at 370 nm in the UV–vis absorption spectra which gets broadened on Fe-doping. The photoluminescence (PL) spectra of the pristine ZnO NPs shows a dominant excitonic peak at 390 nm. On Fe(II)-doping, new PL peaks at 449, 490 and 525 nm appear that are attributed to Zn-interstitials (Zni), oxygen vacancies (VO) and Zn vacancies (VZn), respectively. For all the Fe-doped ZnO NPs, M vs H plots have a complex non-saturating appearance indicating combination of ferromagnetic (FM) and paramagnetic (PM) behaviors. The subtraction of PM contribution revealed the FM curves with saturation magnetization (Ms). On going from 1% to 5% Fe-doping, the Ms values increase substantially by 39 times (0.00361 → 0.1398 emu/g) whereas the paramagnetic susceptibility, χP, increased 35 times (0.28 × 10−6 → 9.72 × 10−6 emu g−1 Oe−1).

Optical Characterization of Ferric-Doped ZnO Thin Film Deposited By Chemical Bath Deposition Method

Fe-doped ZnO holds numerous potential uses in devices such as UV light emitters, piezoelectric transducers, transparent electronics in solar cells, and bright windows as an II-VI semiconductor material. This study looked into the band gap, surface characteristics, optical transmittance, and absorbance of ZnO thin films with Fe doping in different pH conditions such as 8, 9, and 10. The films were prepared using the chemical bath deposition (CBD) method at 350 °C on a glass substrate. The samples were characterized using UV-visible spectroscopy and scanning electron microscopy (SEM). The SEM images of the undoped samples exhibited a lack of cracks, but the doped samples displayed visible cracks due to the presence of Fe in the films. ZnO thin-film surface shape is altered by pH and Fe doping variations. There is a tendency for the films' visual transmission to decrease when the pH rises. The absorbance for all samples increases in the UV and declines in the visible. Fe doping causes the optical band gap Eg to drop. The band gap of both doped and undoped samples reduces when pH rises.

Mössbauer and magnetic studies of Fe-doped ZnO nanoparticles prepared by solution co-precipitation method

A series of Zn[Formula: see text]FexO ([Formula: see text], 0.015, 0.045, 0.075) nanoparticles were synthesized using the solution co-precipitation method, and their structural and property characteristics were investigated. X-ray diffraction (XRD) analysis revealed that all Zn[Formula: see text]FexO samples exhibited a hexagonal wurtzite crystal structure with the P63mc space group. The introduction of Fe doping led to a slight lattice distortion in the samples. The morphology of the nanoparticles, including polydispersion and agglomeration, as well as the presence of the second phase ZnFe2O4, was examined by scanning electron microscope (SEM) and transmission electron microscope (TEM). UV–Vis diffuse reflectance spectroscopy demonstrated that the band gap of Zn[Formula: see text]FexO lies between 3.152 and 3.163[Formula: see text]eV. With the increase in Fe ion doping, the band gap shows a slight decreasing trend. Mössbauer spectroscopy revealed that iron ions in the nanoparticles existed in a trivalent state and exhibited two different configurations: One involved iron replacing zinc without creating a vacancy, while the other involved iron substituting zinc with a vacancy. The ferromagnetic nature of the Fe-doped samples can be attributed to the exchange interaction between two Fe[Formula: see text] ions mediated by the F-center mechanism.

Influence of thermal treatment and Fe doping on ZnO films by ultrasonic spray pyrolysis

Zinc Oxide and Fe-doped ZnO films (1, 2, 3 %) were deposited onto glass substrates by ultrasonic spray pyrolysis. Then, the films were thermally treated at 500 °C for 2 h. Findings revealed that both Fe doping and thermal treatment changed film properties. Films presented hexagonal wurtzite structures without any secondary phases for all films. The preferential orientation (002) changed to dominant growth directions (100) and (002) according to the doping concentration and thermal treatment. The grain size of the ZnO nanogranules decreased after Fe doping and also thermal treatment. The optical transparency was found maximum of 77 % in the visible region. 3 % Fe doping and thermal treatment caused the reduction in the optical band gap values to 3.18 eV. Fourier transform infrared spectroscopy analysis presented the Z-O stretching, CH vibration, and OH stretching bonds. Shifting in the peak position indicated the Fe+2 ion substitution. Photoluminescence analyses revealed the reduced emission intensity with the effect of thermal treatment. Photocatalytic performance tests showed improved degradation efficiency after the films were thermally treated. Especially among Fe-doped films, thermally treated 1 % Fe-doped ZnO film showed a significant increment after as-deposited ones. Consequently, it has been uncovered that thermal treatment and Fe doping significantly influence the investigated film properties.

Shell-Fe/ZnO: A recyclable catalyst with Fe-doped ZnO shell structure for photocatalytic oxidative degradation of tetracycline hydrochloride

In this work, a solvothermal approach was employed to load Fe and Zn elements onto processed diatom frustules, and Shell-Fe/ZnO composite photocatalyst was prepared through high-temperature annealing. The prepared Shell-Fe/ZnO composite demonstrated a degradation efficiency of 96.56 % towards TC-HCl within 120 min. Shell-Fe/ZnO was characterized using TGA, XRD, SEM, EDS. TEM, XPS and UV–vis DRS. Furthermore, the study also explored potential influencing factors such as pH, TC-HCl concentration and catalyst dosage. The results indicated that Shell-Fe/ZnO composite exhibits remarkable structural stability and reproducibility in practical applications. Burst experiments demonstrated that both components O2- and h+ contributed to the decomposition of TC-HCl. The verification of burst experimental results was supported by TOC testing and first-order kinetic modeling.The renewable nature of diatom frustules and the ferromagnetic properties of Fe reduced the production and usage costs of the catalyst, paving the way for the development of sustainable, highly efficient, and recyclable catalysts, thereby providing a novel direction for the photochemical degradation of TC-HCl.

Preparation and characterization of Fe-ZnO cellulose-based nanofiber mats with self-sterilizing photocatalytic activity to enhance antibacterial applications under visible light.

Bacterial infections and antibiotic resistance have posed a severe threat to public health in recent years. One emerging and promising approach to this issue is the photocatalytic sterilization of nanohybrids. By utilizing ZnO photocatalytic sterilization, the drawbacks of conventional antibacterial treatments can be efficiently addressed. This study examines the enhanced photocatalytic sterilizing effectiveness of Fe-doped ZnO nanoparticles (Fe-ZnO nanohybrids) incorporated into polymer membranes that are active in visible light. Using the co-precipitation procedure, Fe-ZnO nanohybrids (Fe x Zn100-x O) have been generated using a range of dopant ratios (x = 0, 3, 5, 7, and 10) and characterized. The ability to scavenge free radicals was assessed and the IC50 value was calculated using the DPPH test at different catalytic concentrations. PXRD patterns showed a hexagonal wurtzite structure, which indicated that the particle size of the nanohybrid decreased as the dopant concentration rose. It was demonstrated by UV-vis diffuse reflectance experiments that the band gap of the nanohybrid decreased (redshifted) with Fe doping. The photocatalytic activity under sunlight increased steadily to 87% after Fe was added as a dopant. The Fe 5%-ZnO nanohybrid exhibited the lowest IC50 value of 81.44 μg mL-1 compared to ZnO, indicating the highest radical scavenging activity and the best antimicrobial activity. The Fe 5%-ZnO nanohybrid, which is proven to have the best photocatalytic sterilization activity, was then incorporated into a cellulose acetate polymer membrane by electrospinning. Disc diffusion assay confirmed the highest antimicrobial activity of the Fe 5%-ZnO nanohybrid incorporated electrospun membrane against Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), and Candida albicans (ATCC 10231) under visible light. As a result, Fe 5%-ZnO nanofiber membranes have the potential to be employed as self-sterilizing materials in healthcare settings.

Electrochemical detection of tryptophan in fish and pharmaceutical supplement at glassy carbon electrode modified with Fe doped ZnO nanoparticle

AbstractThe co‐precipitation approach was employed in this study to create Fe doped ZnO (Fe‐ZnO) nanoparticles (NPs). To characterize the synthesized NPs, Ultra violet‐Visible (UV‐Vis) spectroscopy, X‐ray diffraction (XRD), fourier transform infrared (FT‐IR), scanning electron microscopy (SEM), and Brunauer‐Emmett‐Teller (BET) were used. Here, a novel electrochemical approach for the detection of tryptophan (Trp) using a glassy carbon electrode modified with Fe‐ZnO NPs (Fe‐ZnO/GCE) is demonstrated. The research findings revealed that Fe‐ZnO/GCE enhanced the electron transfer rate of Trp oxidation. The sensitivity of Trp detection using Fe‐ZnO/GCE in phosphate buffer solution (PBS) at pH 64.0 was significantly improved compared to bare GCE due to the electrocatalytic activity of Fe‐ZnO NPs. Fe‐ZnO/GCE exhibited a linear response with Trp concentrations ranging from 0.1 to 150 μM with the limit of detection (LOD) is 0.089 μM (3σ/m) and limit of quantification (LOQ) about 0.3 μM (10σ/m) using linear sweep voltammetry (LSV). The Fe‐ZnO/GCE sensor was also effectively used to detect Trp in African catfish and multivitamin tablets. Trp analysis in real samples exhibited good recovery values of 89.60 to 99.15 %, demonstrating the accuracy and practicality of the method.

Synthesis of Ethylene Carbonate by Urea Transesterification Using Zeolitic Imidazolate Framework Derived Fe-Doped ZnO Catalysts.

The development of environmentally friendly and efficient methods for the synthesis of ethylene carbonate (EC) is crucial for advancing carbon capture, utilization, and storage technologies. Herein, we present the synthesis of EC through the transesterification of urea with ethylene glycol (EG) using a zeolitic imidazolate framework (ZIF) derived Fe-doped ZnO catalyst (Fe;ZnO-ZIF). The Fe;ZnO-ZIF catalyst, prepared by incorporating Fe dopant atoms into a ZnO-ZIF template, demonstrates excellent catalytic activity, achieving high conversion of reactants and superior selectivity toward EC at 160 °C for 150 min under an applied vacuum (160 mmHg). Based on the thermogravimetric, X-ray spectroscopic, and temperature-programmed desorption analysis, the simultaneous presence of strong Lewis acidic and basic sites in Fe;ZnO-ZIF enables its excellent catalytic performance toward EC synthesis with high selectivity. Acidic sites activate the carbon center in urea, while basic sites facilitate the nucleophilic attack on urea by deprotonation of EG. This synergistic reaction pathway resulting from the interaction between the strong Lewis acidic and basic sites promotes nucleophilic attacks of EG on urea, leading to significantly higher conversion efficiency and selectivity, compared to the commercial benchmark ZnO. Although the establishment of a continuous reaction system which takes into account cyclability and stability of the catalysts is further required in the future, our research reported herein provides valuable insights into the design of synergistic, localized active sites for EC synthesis and contributes to the development of sustainable carbon utilization technologies for achievement of net-zero emissions.

Investigating the Photocatalytic Degradation of Amaranth Dye in Water Environment using Visible Light‐Activated Fe‐Doped ZnO Nanoparticles

These days, the removal of dissolved organics from industrial waste water is a foremost challenge to the scientific community to attain the conservation of the aqueous ecosystem. The present work emphasizes the photocatalytic degradation of industrial dye, that is, Amaranth using Fe‐doped ZnO (Fe‐ZnO) nanoparticles. The formation of wurtzite phase bare ZnO and Fe‐ZnO materials fabricated by the solvothermal route is confirmed by XRD and Fourier‐transform infrared spectroscopy, whereas the scanning electron microscopy morphological investigations reveal the formation of coral‐like to granular particles. The bandgap energies of the synthesized materials are observed to be shifted to the blue region on gradual Fe doping, indicating the suitability of the material for photocatalysis. The photocatalytic activity of the as‐synthesized ZnO and Fe‐ZnO materials is evaluated under sunlight and mercury lamp light, wherein the 6% Fe‐ZnO material shows more than 98% degradation of Amaranth dye within 80 min in sunlight. The kinetic studies shows pseudo‐first‐order degradation reaction with a rate constant of 0.0114 min−1 in sunlight. The effects of catalyst loading, light source, and stability of the photocatalyst are also explored along with a proposed photogenerated free radical‐based dye degradation mechanism.

Anodic water oxidation to H2O2 on Fe-doped ZnO for electro-Fenton wastewater purification

Anodic water oxidation to H2O2 on Fe-doped ZnO for electro-Fenton wastewater purification

Electrochemical determination of endrin from fruit juice samples based on Fe-doped ZnO nanomaterial modified glassy carbon electrode

Electrochemical determination of endrin from fruit juice samples based on Fe-doped ZnO nanomaterial modified glassy carbon electrode

Influence of Fe Doping on the Electrochemical Performance of a ZnO-Nanostructure-Based Electrode for Supercapacitors.

ZnO is a potential candidate for providing an economic and environmentally friendly substitute for energy storage materials. Therefore, in this work, Fe-doped ZnO nanostructures prepared using the microwave irradiation procedure were investigated for structural, morphological, magnetic, electronic structural, specific surface area and electrochemical properties to be used as electrodes for supercapacitors. The X-ray diffraction, high-resolution transmission electron microscopy images, and selective-area electron diffraction pattern indicated that the nanocrystalline structures of Fe-doped ZnO were found to possess a hexagonal wurtzite structure. The effect of Fe doping in the ZnO matrix was observed on the lattice parameters, which were found to increase with the dopant concentration. Rods and a nanosheet-like morphology were observed via FESEM images. The ferromagnetic nature of samples is associated with the presence of bound magnetic polarons. The enhancement of saturation magnetization was observed due to Fe doping up to 3% in correspondence with the increase in the number of bound magnetic polarons with an Fe content of up to 3%. This behavior is observed as a result of the change in the oxidation state from +2 to +3, which was a consequence of Fe doping ranging from 3% to 5%. The electrode performance of Fe-doped ZnO nanostructures was studied using electrochemical measurements. The cyclic voltammetry (CV) results inferred that the specific capacitance increased with Fe doping and displayed a high specific capacitance of 286 F·g-1 at 10 mV/s for 3% Fe-doped ZnO nanostructures and decreased beyond that. Furthermore, the stability of the Zn0.97Fe0.03O electrode, which was examined by performing 2000 cycles, showed excellent cyclic stability (85.0% of value retained up to 2000 cycles) with the highest specific capacitance of 276.4 F·g-1, signifying its appropriateness as an electrode for energy storage applications.

Effect of Fe doped and capping agent – Structural, optical, luminescence, and antibacterial activity of ZnO nanoparticles

Zinc oxide nanoparticles (ZnO NPs) are indispensable materials for spectral and optical phenomena, prepared by a chemical precipitation method. We studied their properties resulting from different dopants in the nanoscale. The samples' structure, texture, energy band, and photoluminescence were examined using XRD, TEM, FTIR, PL, and UV–VIS spectroscopy. XRD shows the single hexagonal Wurtzite with crystallite sizes from 10.1 to 17.8 nm and the spherical shape particles. The octahedral sites at 470–489 cm−1 and the tetrahedral sites at 616 cm−1 were observed in the FTIR studies. PL showed a wider bandgap, better UV emission, and decreased defect density of the Fe doped than that of the pristine one. Fe-doped ZnO NPs are more active than pristine ZnO NPs for their quenching or absorbing properties, indicating their antibiotic properties.

Synthesis and application of manganese-doped zinc oxide as a potential adsorbent for removal of Congo red dye from wastewater

Synthetic dyes are considered toxic compounds and as such are not easily removed by conventional water treatment processes. This study demonstrated the synthesis of pure and manganese- (Mn), silver- (Ag), and iron- (Fe) doped zinc oxide (ZnO) nanoparticles via the wet chemical route. In particular, it investigated the batch adsorption studies and physiochemical properties of synthesized pure and doped ZnO materials for removing toxic congo red (CR) dye. X-ray diffraction (XRD), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDS) confirmed the synthesis of the pure and doped ZnO materials. The batch adsorption investigation revealed adsorption efficiencies of 99.4% for CR dye at an optimal dose of 0.03 g/30 ml for Mn-doped ZnO at a solution pH of 2. The adsorption capacity of each of the synthesized materials was found to be in order Mn-doped ZnO (232.5 mg/g) > Ag-doped ZnO (222.2 mg/g) > pure ZnO (212.7 mg/g) > Fe-doped ZnO (208.3 mg/g). Both pseudo-second-order kinetics model and the Langmuir isotherm model accurately explained the adsorption behaviors of CR dye. As such, Van der Waal interactions, H-bonding, and electrostatic interaction were found to be the adsorption mechanisms responsible for dye removal. In addition, the desorption–regeneration investigation indicated the successful reuse of the exhausted Mn-doped ZnO material for five cycles of CR dye adsorption with an efficiency of 83.1%. Overall, this study has demonstrated that Mn-doped ZnO could be considered a viable adsorbent for the cleanup of dye-contaminated water.

Defect structures and (ferro)magnetism in Zn1-xFexO nanoparticles with the iron concentration level in the dilute regime (x = 0.001 – 0.01) prepared from acetate precursors

Zn1-xFexO nanoparticles with the iron concentrations level in the dilute regime (x = 0.001–––0.01) were produced by a sol–gel route from acetate precursors along with an un-doped and 3 at.% Fe-doped reference. The X-ray diffraction of the un-doped and 0.1–1 at.% Fe-doped samples reveal the reflections for only the ZnO wurtzite structure. Fe doping enhances the a-axis lattice constant, the unit cell volume and the microstrain. Iron doping reduces the average crystallite/particle size (confirmed by Scanning Electron Microscopy), improving the surface-to-volume ratio or the concentration of defective surface sites. XPS identifies the iron in both Fe3+ and Fe2+ states. XPS and 57Fe Mossbauer spectroscopy indicate a broad distribution (distortion) of Fe3+ sites on the surface of ZnO nanoparticles. The blue shift and broadening of the UV emission, and quenching of defect-related photoluminescence in the Fe-doped samples verify the presence of iron in the ZnO lattice and surface intrinsic defects. 0.1–1 at.% Fe-doped ZnO show room temperature ferromagnetism, RTFM, characteristic of dilute magnetic semiconductors, DMS. The magnetization measurements with temperature evidence an antiferromagnetic alignment and an increase of ferromagnetic contribution with Fe doping up to 1 at.%. Zn0.97Fe0.3O reference is a superparamagnetic ZnO/ZnFe2O4 nanocomposite with a blocking temperature of 20 K; HRTEM shows (ultra)fine ZnFe2O4 particles at the surface of ZnO nanoparticles. The analysis of experimental data of 0.1–1 at.% Fe-doped ZnO was done in terms of iron coupling with intrinsic defects, which can generate surface Fe3+ states with geometries similar to the Fe3+ in inverse spinel ZnFe2O4. The superexchange interaction (resembling that in the inverse spinel ZnFe2O4) between the Fe3+ sites with distorted configuration resulting in ferrimagnetism was hypothesised as a possible mechanism of RTFM. Experimental (structural, local chemical, magnetic, optical) and interpretation results can be used to optimize the processing conditions for Fe-doped ZnO to serve as an effective DMS, e.g. for spintronic applications.

Structural, optical and magnetic characteristics of iron doped zinc oxide thin films

Zn1-xFexO films with x = 0, 5, 10, 15 and 20 at.% were prepared under high vacuum by the electron beam gun evaporation. The impact of Fe doping concentration on the films' structural, optical and magnetic characteristics has been taken into account. The patterns of XRD for all films at various Fe concentrations showed wurtzite-type structures. The results show that the size of nano-films reduces from 24 nm (0%) to 11 nm (0.20%) with elevating Fe content, which is owing to the difference between the ionic radii of Zn and Fe. Peaks associated with the elements to be seen were visible in the XPS spectra of undoped and 10% Fe-doped ZnO nanoparticles produced by the precipitation process: zinc (Zn), iron (Fe), and oxygen (O). The optical constants (n, k) of the Zn1-xFexO films were obtained by the SE measurements by an ellipsometric model, allowing for the verification of the Fe3+ ions in Fe-doped ZnO. With the addition of Fe, the energy band gap decreased from 3.44 eV to 3.28 eV. M-H measurements revealed room-temperature ferromagnetism in Fe-doped ZnO thin film. As the Fe concentration rises, the magnetization increases until it reaches a concentration of 15%, at which point it starts to decrease. This decrease in magnetization was attributable to the spinel phase, which was seen in the XRD spectra. These findings imply that Fe-doped ZnO is a highly suggested material for the creation of spintronic and optoelectronic devices.

Photoluminescence and Photocatalytic Properties of MWNTs Decorated with Fe-Doped ZnO Nanoparticles

The present work reports the photoluminescence (PL) and photocatalytic properties of multi-walled carbon nanotubes (MWCNTs) decorated with Fe-doped ZnO nanoparticles. MWCNT:ZnO-Fe nanocomposite samples with weight ratios of 1:3, 1:5 and 1:10 were prepared using a facile synthesis method. The obtained crystalline phases were evidenced by X-ray diffraction (XRD). X-ray Photoelectron spectroscopy (XPS) revealed the presence of both 2+ and 3+ valence states of Fe ions in a ratio of approximately 0.5. The electron paramagnetic resonance EPR spectroscopy sustained the presence of Fe3+ ions in the ZnO lattice and evidenced oxygen vacancies. Transmission electron microscopy (TEM) images showed the attachment and distribution of Fe-doped ZnO nanoparticles along the nanotubes with a star-like shape. All of the samples exhibited absorption in the UV region, and the absorption edge was shifted toward a higher wavelength after the addition of MWCNT component. The photoluminescence emission spectra showed peaks in the UV and visible region. Visible emissions are a result of the presence of defects or impurity states in the material. All of the samples showed photocatalytic activity against the Rhodamine B (RhB) synthetic solution under UV irradiation. The best performance was obtained using the MWCNT:ZnO-Fe(1:5) nanocomposite samples, which exhibited a 96% degradation efficiency. The mechanism of photocatalytic activity was explained based on the reactive oxygen species generated by the nanocomposites under UV irradiation in correlation with the structural and optical information obtained in this study.

Structural, optical, photoluminescence and magnetic investigation of doped and Co-doped ZnO nanoparticles

We report here the structural, optical, photoluminescence (PL), and magnetic investigation of Zn1−x−yFexMyO nanoparticles. The lattice constants and crystallite size are decreased by Fe, followed by a further decrease up to (Fe + M) = 0.30. A compressive stress is approved and the size of particle is between 180 and 277 nm and follows the sample order of ZnO, (Fe + Cu), (Fe + Ni), and Fe. Although a single value of energy gap (Eg) is found for pure and Fe-doped ZnO, two values of Eg (Egh and Egl) are found for the co-doped samples. The Eg is generally increased by Fe, followed by a further increase for the Cu-series, whereas it is decreased for the Ni-series. The refractive indices nK and nT proposed by different methods are generally decreased by Fe, followed by a further decrease for both series. Although Fe doped ZnO depressed the density of carriers (N/m*), it increased again for the co-doped samples. The residual dielectric constant ϵL is decreased by Fe, followed by an increase for the Cu-series, but it is decreased for the Ni-series. The loss factor tan δ increases slightly with Fe, followed by an increase for the Ni-series, but it decreases in the Cu-series. A significant depression of optical conductivity σopt by Fe was obtained, followed by a further decrease which is higher for the Cu-series. The PL shows four visible emissions. Interestingly, an IR emission at about 825 nm is only obtained for the co-doped samples. Furthermore, the blue emission (Iblue) was higher than UV (IUV), [(Iblue/IUV) > 1], but it is greater for the Ni series than the Cu. Although ZnO exhibits diamagnetic behavior, the Fe and co-doped samples exhibit ferromagnetic with higher magnetization for the Ni-series than the Cu. The current results recommend the co-doped samples in nanoscale for some of advanced devices.

Optical, Photocurrent, Electrical, Structural, and Morphological Properties of Magnetron Sputtered Pure and Iron-Doped Zinc Oxide Thin Films

Due to its excellent physical and chemical properties, transition metal-doped zinc oxide has potential applications in different fields. In this research paper, pure and iron-doped ZnO films were deposited by thermal oxidation of sputtered metallic zinc and iron. The effect of iron (Fe) doping on the optical, morphology, structural, electrical, and photocurrent properties of zinc oxide films was examined. The X-ray diffraction analysis shows a wurtzite structure with preferential orientation for all films, where the high texture coefficient values (above 3) corresponded to the (002) plane. Fe doping reduced the crystallite size from 12.3 to 8.7 nm and lattice constants c and a values from 5.19 to 5.155 Å and from 3.236 to 3.203 Å respectively. The different calculated structure parameters, confirm the incorporation of Fe (Fe3+) in the ZnO lattice. The surface morphology of thin films measured using atomic force microscopy revealed that the Fe doping could markedly decrease the grains size from 248 to 54 nm and the Root–Mean–Square roughness of films from 5.27 to 4.22 nm. For all films, the transmittance analysis shows a transmittance above 90% in the visible region and with an increase in the Fe concentration, the transmittance, and the absorption in the ultraviolet region were increased. The gap energy of ZnO strongly increased from 3.26 to 3.51 eV with doping. The effect of Fe doping on different optical parameters was discussed in detail. The photoluminescence analysis of pure and doped ZnO exhibits one ultraviolet emission (384 nm) and green emission. Compared to pure ZnO, the ultraviolet peak intensity decreased as Fe content increased. The electrical resistivity was decreased and the photocurrent properties of ZnO were enhanced by Fe doping. In this report, Fe-doped ZnO films exhibited remarkable properties. Therefore such films can be usefully used in different device applications.

Investigation of bulk magneto-resistance crossovers in iron doped zinc-oxide using spectroscopic techniques

Pellets of Pure and Fe-doped dilute magnetic semiconducting (DMS) samples are studied for bulk magneto-resistance (BMR) at room temperature and at low-temperatures ∼100K. Raman-, photoluminescence- and X-ray photoelectron-spectroscopic techniques are used to determine chemical and electronic structures of the samples. A broadband intense yellow-green-orange luminescence is observed in Fe-doped ZnO samples and emission red-shifts are investigated. Electrical transport is studied with and without applied magnetic field up to 9T and thermal activation and hopping modes of conduction is discussed in light of nature of Fe substitution in the host lattice. Several decremental- to incremental-BMR crossovers are obtained corresponding to experimental variables of Fe concentration 0.025 ≤ x ≤ 0.1, temperature and applied magnetic field. Several possible modes of magneto-transport are discussed to further elucidate the origin of the as-found BMR crossovers in our samples. Positive BMR in pure- and highly doped (x ≥ 0.1) ZnO is found to originate from F-centers and thermal fluctuations, respectively. However, modestly doped (x ≤ 0.05) ZnO exhibit thermally activated conduction and magnetic poloron mediated negative BMR.