Manganese Doped Zinc Oxide Research Articles

Optimization and kinetics of biodiesel production from Mahua oil using manganese doped zinc oxide nanocatalyst

The production of biodiesel has rapid development in the recent years due to the benefits associated with its ability to minimize environmental pollution. Heterogeneous catalyst for production of biodiesel is a preferred route for its easier recovery and no demand for aqueous treatment. Transesterification of fatty acids into biodiesel using transition metal oxide gives higher conversion into their corresponding methyl esters in a short time. In the present work, manganese doped zinc oxide is used as a heterogeneous catalyst for the production of biodiesel from Mahua oil. The synthesized manganese doped zinc oxide nanocatalyst was characterized by XRD and SEM. The SEM and XRD results confirmed the hexagonal structure of the catalyst with the particle size of 24.18 nm. The 8% (w/v) catalyst concentration, 1:7% (v/v) of oil to methanol ratio, 50 min of reaction time and 50 °C of reaction temperature were found to be the optimum process condition for the maximum biodiesel yield of 97%. The presence of methyl esters in biodiesel was confirmed by FT-IR and GC-MS analysis.

Structural, morphological, optical and antibacterial activity of rod-shaped zinc oxide and manganese-doped zinc oxide nanoparticles

Pure ZnO and Mn-doped ZnO nanoparticles were synthesized by Co-precipitate method. The structural characterizations of the nanoparticles were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. UV–Vis, FTIR and photoluminescence (PL) spectroscopy were used for analysing the optical properties of the nanoparticles. XRD results revealed the formation of ZnO and Mn-doped ZnO nanoparticles with wurtzite crystal structure having average crystalline size of 39 and 20 nm. From UV–Vis studies, the optical band-gap energy of 3.20 and 3.25 eV was obtained for ZnO and Mn-doped ZnO nanoparticles, respectively. FTIR spectra confirm the presence of ZnO and Mn-doped ZnO nanoparticles. Photoluminescence analysis of all samples showed four main emission bands: a strong UV emission band, a weak blue band, a weak blue–green band and a weak green band indicating their high structural and optical qualities. The antibacterial efficiency of ZnO and Mn-doped ZnO nanoparticles were studied using disc diffusion method. The Mn-doped ZnO nanoparticles show better antibacterial activity when higher doping level is 10 at% and has longer duration of time.

A High Photo-Catalytic Activity of Magnetic Composite Based on Chitosan and Manganese-Doped Zinc Oxide Nanoparticles for Removal of Dyeing Wastewater

A High Photo-Catalytic Activity of Magnetic Composite Based on Chitosan and Manganese-Doped Zinc Oxide Nanoparticles for Removal of Dyeing Wastewater

Influence of annealing on the linear and nonlinear optical properties of Mn doped ZnO thin films examined by z-scan technique in CW regime

We present the studies on the influence of annealing on the third-order nonlinear optical properties of RF magnetron sputtered manganese doped zinc oxide (MZO) thin films with different doping concentration. It is revealed that the incorporation of Mn into ZnO and annealing lead to prominent changes in the third order nonlinearity. Nonlinear optical measurements were carried out by employing the z-scan technique using a continuous wave (CW) HeNe laser of 633 nm. The z-scan results reveal that the films exhibit self-defocusing thermal nonlinearity. The third-order nonlinear optical susceptibility χ(3) was found to be of the order of 10−3 esu and 10−2 esu for annealed MZO thin films at 200 °C and 400 °C respectively. The dependence of grain size on the observed nonlinearity was revealed by atomic force microscopy analysis. Optical limiting studies were carried out for a range of input power levels and an optical limiting of about ∼8 mW was observed indicating the possible application for photonic devices.

Magneto-Optical Studies of Manganese-Doped Zinc Oxide Nanoparticles by Ionic Liquid Assisted Synthesis Route

Magneto-Optical Studies of Manganese-Doped Zinc Oxide Nanoparticles by Ionic Liquid Assisted Synthesis Route

Reduction in the Band Gap of Manganese-Doped Zinc Oxide: Role of the Oxidation State

Manganese-doped zinc oxide powders were synthesized by solid state reaction of the respective oxides. The high-temperature conditions were chosen such that multiple valence states of manganese were doped in the host zinc oxide lattice. Structural characterization was carried out to confirm the doping and to find the maximum amount of manganese that can be incorporated. Diffuse reflectance spectroscopy was used to measure the optical band gap of the doped sample and the lowering with respect to pure ZnO was attributed to the presence of higher oxidation states of manganese. The presence of these oxidation states was confirmed using x-ray photoelectron spectroscopy. The study shows that a solid state reaction is a viable route for synthesizing doped metal oxides with desired optical properties.

Effect of Mn content on structural, optical, opto-thermal and electrical properties of ZnO:Mn sprayed thin films compounds

Manganese-doped zinc oxide thin films (ZnO:Mn) at different percentages (0–3%) were deposited on glass substrates using a chemical spray technique. The effects of manganese element content on structural, optical, opto-thermal and electrical conductivity of ZnO:Mn thin films were investigated by means of X-ray diffraction, optical measurement, Photoluminescence spectroscopy and impedance spectroscopy. XRD analysis revealed that all films consist of single phase ZnO and were well crystallized in würtzite phase with the crystallites preferentially oriented towards (002) direction parallel to c-axis. Doping manganese resulted in a slight decrease in the optical band gap energy of the films and a noticeably change in optical constants. The UV peak positions for ZnO:Mn samples slightly red shift to the longer wavelength in comparison with the pure ZnO which can be attributed to the change in the acceptor level induced by the substitutional Mn2+ and the band-gap narrowing of ZnO with the Mn dopant. We have performed original AC and DC conductivity studies inspired from Jonscher and small polaron models. These studies helped establishing significant correlation between temperature and activation energy and Mn content. From the spectroscopy impedance analysis we investigated the frequency relaxation phenomenon and the circuit equivalent circuit of such thin films. Finally, all results have been discussed, as an objective of the actual work, in terms of the manganese doping concentration.

B-Chronic Lymphocytic Leukemia Autophagyc Cell Death by the Use of Manganese Doped Zinc Oxide Nanoparticles and Photo-Dynamic Therapy.

B-Chronic Lymphocytic Leukemia (B-CLL) usually follows an adverse, relentless clinical course by slowly developing drug resistance to fludarabine and other chemotherapeutic agents, as well as by acquiring new different genetic abnormalities. As B-CLL cells spontaneously produce high amounts of Reactive Oxygen Species (ROS) having an altered redox state in relation to that of normal B lymphocytes, we decided to probe different metal Zinc nanoparticles (ZnNPs) and quantify the levels of Singlet Oxigen (SO) to see if variations of its intracellular concentrations could execute and accelerate deadly programs in leukemic cells rather than in normal B lymphocytes, when applied with Photodynamic Therapy (PDT). In this way, we developed and tested a variety of metal ZnNPs of which one made of 0.5% Manganese Doped Zinc Oxide (ZnO:Mn) was finally selected for further testing as it had the best fludarabine resistant B-CLL cells in vitro killing activity, specially when combined with PDT. An interesting and rapidly dying process of B-CLL cells, known as autophagy, was always seen under Transmission Electronic Microscopy (TEM) when incubated with these 0.5% Mn doped ZnO NPs. This phenomenon correlated well with those intracellular increases of SO when PDT was administered, and measured by a novel method first described by us. As this therapy seems to be very specific to fludarabine resistant B-CLL cells, producing almost no damage to normal lymphocytes, it could surely contribute in the near future as a new innovative targeted strategy to be delivered in the clinical setting for the definitive benefit of these bad prognostic patients.

Structural, luminescence and magnetic properties of Mn doped ZnO thin films using spin coating technique

Manganese doped zinc oxide (ZnO) thin films were synthesized for various wt% doping of Mn using sol–gel spin coating technique. The effects of Mn doping on the structural, morphological, compositional, photoluminescence (PL) and magnetic behaviour of ZnO thin films were investigated. Although, Mn doping did not change the lattice constants of the films, the texture coefficient is found to be improved for the films having higher percentage of Mn doping. PL studies reveal that as doping concentration of Mn increases, the intensity of emission peaks corresponding to violet and blue colour increases and the peak position shifts slightly. The saturated magnetic moments are found to decrease with the increase in Mn doping and the reason for such behavior is discussed.

Correlation between the OES Plasma Composition and ZnMnO films properties during Pulsed Laser

Manganese doped zinc oxide was ablated on (100) silicon using the fundamental harmonics of Nd:YAG laser at various oxygen ambient gas pressures and temperature substrate was kept at room temperature during the deposition. In all experiments we used ZnMnO target. Optical emission spectroscopy (OES) is used to survey the plasma composition during deposition. The intensities of the Znl and ZnlI emission lines are correlated to the oxygen gas pressure and composition and morphology of the films deposited. Strong emission lines of Znl, Zn II and neutral oxygen are observed. Oxygen and Mn emission lines in its atomic or ionic states have not been detected in this investigation, which is thought ZnMnO as being exclusively produced on the substrate surface and not generated into the plasma, which is in agreement with previous studies of ZnO plasma plume. Atomic Force Microscopy (AFM) is used to study the influence of oxygen gas pressure on the ZnMnO film morphology. An X-ray diffraction was tried to verify a crystal structure of the sample. We have demonstrated that gas pressure is an important parameter for the quality and performances of ZnMnO structures obtained by pulsed laser deposition.

Artificial neural network modelling of photodegradation in suspension of manganese doped zinc oxide nanoparticles under visible-light irradiation.

The artificial neural network (ANN) modeling of m-cresol photodegradation was carried out for determination of the optimum and importance values of the effective variables to achieve the maximum efficiency. The photodegradation was carried out in the suspension of synthesized manganese doped ZnO nanoparticles under visible-light irradiation. The input considered effective variables of the photodegradation were irradiation time, pH, photocatalyst amount, and concentration of m-cresol while the efficiency was the only response as output. The performed experiments were designed into three data sets such as training, testing, and validation that were randomly splitted by the software's option. To obtain the optimum topologies, ANN was trained by quick propagation (QP), Incremental Back Propagation (IBP), Batch Back Propagation (BBP), and Levenberg-Marquardt (LM) algorithms for testing data set. The topologies were determined by the indicator of minimized root mean squared error (RMSE) for each algorithm. According to the indicator, the QP-4-8-1, IBP-4-15-1, BBP-4-6-1, and LM-4-10-1 were selected as the optimized topologies. Among the topologies, QP-4-8-1 has presented the minimum RMSE and absolute average deviation as well as maximum R-squared. Therefore, QP-4-8-1 was selected as final model for validation test and navigation of the process. The model was used for determination of the optimum values of the effective variables by a few three-dimensional plots. The optimum points of the variables were confirmed by further validated experiments. Moreover, the model predicted the relative importance of the variables which showed none of them was neglectable in this work.

Correlation between the OES plasma composition and ZnMnO films properties during pulsed laser

Manganese doped zinc oxide was ablated on (100) silicon using the fundamental harmonics of Nd:YAG laser at various oxygen ambient gas pressures and temperature substrate was kept at room temperature during the deposition. In all experiments we used ZnMnO target. Optical emission spectroscopy (OES) is used to survey the plasma composition during deposition. The intensities of the ZnI and ZnII emission lines are correlated to the oxygen gas pressure and composition and morphology of the films deposited. Strong emission lines of ZnI, Zn II and neutral oxygen are observed. Oxygen and Mn emission lines in its atomic or ionic states have not been detected in this investigation, which is thought ZnMnO as being exclusively produced on the substrate surface and not generated into the plasma, which is in agreement with previous studies of ZnO plasma plume. Atomic Force Microscopy (AFM) is used to study the influence of oxygen gas pressure on the ZnMnO film morphology. An X-ray diffraction was tried to verify a crystal structure of the sample. We have demonstrated that gas pressure is an important parameter for the quality and performances of ZnMnO structures obtained by pulsed laser deposition.

Preparation of manganese-doped ZnO thin films and their characterization

In this study, pure and manganese-doped zinc oxide (Mn:ZnO) thin films were deposited on quartz substrate following successive ion layer adsorption and reaction (SILAR) technique. The film growth rate was found to increase linearly with number of dipping cycle. Characterization techniques of XRD, SEM with EDX and UV–visible spectra measurement were done to investigate the effect of Mn doping on the structural and optical properties of Mn:ZnO thin films. Structural characterization by X-ray diffraction reveals that polycrystalline nature of the films increases with increasing manganese incorporation. Particle size evaluated using X-ray line broadening analysis shows decreasing trend with increasing manganese impurification. The average particle size for pure ZnO is 29·71 nm and it reduces to 23·76 nm for 5% Mn-doped ZnO. The strong preferred c-axis orientation is lost due to manganese (Mn) doping. The degree of polycrystallinity increases and the average microstrain in the films decreases with increasing Mn incorporation. Incorporation of Mn was confirmed from elemental analysis using EDX. As the Mn doping concentration increases the optical bandgap of the films decreases for the range of Mn doping reported here. The value of fundamental absorption edge is 3·22 eV for pure ZnO and it decreases to 3·06 eV for 5% Mn:ZnO.

Fast Classification of Meat Spoilage Markers Using Nanostructured ZnO Thin Films and Unsupervised Feature Learning

This paper investigates a rapid and accurate detection system for spoilage in meat. We use unsupervised feature learning techniques (stacked restricted Boltzmann machines and auto-encoders) that consider only the transient response from undoped zinc oxide, manganese-doped zinc oxide, and fluorine-doped zinc oxide in order to classify three categories: the type of thin film that is used, the type of gas, and the approximate ppm-level of the gas. These models mainly offer the advantage that features are learned from data instead of being hand-designed. We compare our results to a feature-based approach using samples with various ppm level of ethanol and trimethylamine (TMA) that are good markers for meat spoilage. The result is that deep networks give a better and faster classification than the feature-based approach, and we thus conclude that the fine-tuning of our deep models are more efficient for this kind of multi-label classification task.

Fast Classification of Meat Spoilage Markers Using Nanostructured ZnO Thin Films and Unsupervised Feature Learning

This paper investigates a rapid and accurate detection system for spoilage in meat. We use unsupervised feature learning techniques (stacked restricted Boltzmann machines and auto-encoders) that consider only the transient response from undoped zinc oxide, manganese-doped zinc oxide, and fluorine-doped zinc oxide in order to classify three categories: the type of thin film that is used, the type of gas, and the approximate ppm-level of the gas. These models mainly offer the advantage that features are learned from data instead of being hand-designed. We compare our results to a feature-based approach using samples with various ppm level of ethanol and trimethylamine (TMA) that are good markers for meat spoilage. The result is that deep networks give a better and faster classification than the feature-based approach, and we thus conclude that the fine-tuning of our deep models are more efficient for this kind of multi-label classification task.

Manganese-doped Zinc Oxide Nanopowders for Photocatalytic Decoloration of Reactive Black 5 Textile Dye

Zinc oxide photocatalysts doped with manganese (0.04‐1 at.%) were synthesized via precipitation technique. Their characteristics were studied by Xray diraction (XRD) and BET analysis. The calculated mean size of the crystallites was in the range of 31‐45 nm. Manganese doping of ZnO samples results in slight decrease in crystalline size. Increasing the Mn content in ZnO powders results in a lower photocatalytic activity. The pure ZnO nanopowders decolorate Reactive Black 5 dye under ultraviolet light to almost 92% for 2 h.

Third-order nonlinear optical properties of Mn doped ZnO thin films under cw laser illumination

We report the measurements of third-order nonlinear optical properties of undoped zinc oxide and manganese doped zinc oxide thin films with different doping concentrations investigated using z-scan technique. Thin films were prepared by radio frequency magnetron sputtering using a compound target on glass substrate at room temperature. The structural properties of the deposited films were analysed by X-ray diffraction studies. The atomic force microscope analysis of the deposited films reveals that the grain size and roughness of the films depend on the Mn concentration. The direct energy band gap of the deposited film increases with the increase in Mn concentration in the films. The nonlinear optical measurements were carried out using a cw He–Ne laser at 633nm wavelength. The z-scan results reveal that the films exhibit self-defocusing nonlinearity. The third-order nonlinear optical susceptibility χ(3) is found to be of the order of 10−3esu. The films investigated here exhibit good optical power limiting at the experimental wavelength.

Thermal properties of manganese-doped ZnO polycrystalline films

The thermal conductivity and heat capacity of manganese-doped zinc oxide polycrystals have been studied in the temperature range 30–300 K. A substantial influence of the secondary phase or MnO clusters formed as a result of doping on the temperature dependences of thermophysical properties of polycrystalline zinc oxide films has been shown.

Semi-empirical study of ortho-cresol photo degradation in manganese-doped zinc oxide nanoparticles suspensions.

The optimization processes of photo degradation are complicated and expensive when it is performed with traditional methods such as one variable at a time. In this research, the condition of ortho-cresol (o-cresol) photo degradation was optimized by using a semi empirical method. First of all, the experiments were designed with four effective factors including irradiation time, pH, photo catalyst’s amount, o-cresol concentration and photo degradation % as response by response surface methodology (RSM). The RSM used central composite design (CCD) method consists of 30 runs to obtain the actual responses. The actual responses were fitted with the second order algebraic polynomial equation to select a model (suggested model). The suggested model was validated by a few numbers of excellent statistical evidences in analysis of variance (ANOVA). The used evidences include high F-value (143.12), very low P-value (<0.0001), non-significant lack of fit, the determination coefficient (R2 = 0.99) and the adequate precision (47.067). To visualize the optimum, the validated model simulated the condition of variables and response (photo degradation %) be using a few number of three dimensional plots (3D). To confirm the model, the optimums were performed in laboratory. The results of performed experiments were quite close to the predicted values. In conclusion, the study indicated that the model is successful to simulate the optimum condition of o-cresol photo degradation under visible-light irradiation by manganese doped ZnO nanoparticles.

Synthesis of nanocrystalline zinc manganese oxide by thermal decomposition of new dinuclear manganese(III) precursors

Nanocrystalline manganese-doped zinc oxide was synthesized by thermal decomposition of a zinc oxide sol with two new dinuclear manganese(III) complexes as precursor. Thermal analysis results indicated that the decomposition of manganese precursors occurred at 269 and 314 °C. X-ray structural analysis shows the presence of dimanganese core in the complexes and the binding of the ligands to the manganese(III) is through N2O2. The manganese-doped zinc oxide composite was characterized by means of X-ray diffraction, scanning electron microscopy, and UV–Vis spectroscopy. Structural properties of the composites elucidated that the manganese ions have substituted the zinc ions without changing the wurtzite structure of zinc oxide.