Manganese Doping Research Articles

Effect of Mn on lithium-sulphate-borated based glass as energy storage applications

Li2S-2H3BO3 glasses with and without 4 mol% MnO2 dopant were successfully synthesized. The effect of manganese doping in glasses were studied by XRD, TEM, and UV-Vis, respectively. The magnetism of glasses were measured by vibrating sample magnetometer (VSM). The parent glass exhibited mixed behaviors between ferromagnetism and diamagnetism, while ferromagnetism and paramagnetism were observed for glass doped with 4 mol % of MnO2. The electrochemical properties of vitreous cathodes were studied by cyclic voltammetry (CV). Interestingly, glasses doped with MnO2 show better pseudocapacitive behavior with the highest specific capacitance of ~49 F.g−1 at scan rate of 5 mV.s−1. Furthermore, the valence states of Mn and S in glasses were investigated by XANES. Mixing oxidation states of Mn2+/Mn3+ ions was observed and the S6+ ions with 6-fold oxygen coordinated network around S atoms was revealed. The existing of sulfur atoms in glass system was enhanced conductivity by substitution into oxygen vacancy.

Investigation of dielectric, magnetic and impedance spectroscopic properties of CaCu3-XMnXTi4-XMnXO12 (X = 0.10) nano-ceramic synthesized through semi-wet route

This communication reports a detail study on manganese (Mn) doping in CaCu3Ti4O12 (CCTO) ceramic (simultaneously doping copper and titanium site) with the help of X-ray Photoelectron Spectroscopy ( XPS), High Resolution - Scanning Electron Microscopy ( HR-SEM), High Resolution- Transmission Electron Microscopy (HR-TEM ) and Raman spectra. The doping of manganese in CCTO ceramic, the dielectric constant was largely decreased due to Mn exist variable oxidation state like Mn+2, Mn+3and Mn+4 due to this reason the grains (GB) and grain boundaries (GBs) slightly behave conducting nature. Raman spectra show the existence of copper oxide and manganese oxide presence in the grain and grain boundary of CaCu2.9Mn0.1Ti3.9Mn0.1O12 (CCMTMO) ceramic. The novelty of Mn-doped CCTO ceramic is that the tangent loss also decreases largely as compared to CCTO ceramic. The dielectric constant and tangent loss of CCMTMO ceramic 375 and 0.3 at 10 Hz temperature, respectively. CCMTMO ceramic is very useful for microelectronic devices. The polycrystalline nature of CCMTMO was to be studied with the help of X-ray diffraction (XRD), HR-SEM, HR-TEM, and Magnetic Property Measurement System (MPMS, Quantum Design). The elemental analysis and oxidation state was confirmed by (Energy Diffraction X-ray) EDX and XPS respectively. The elements were found to be their required stoichiometric and oxidation state. The impedance and modulus spectroscopy also studied.

Characteristics of diluted magnetic semiconductor based on Mn-doped TiO2 nanorod array films

In this work, un-doped and Mn-doped TiO2 nanorod (NR) array films were successfully prepared by hydrothermal method that deposited on FTO substrate at different molar ratios (x = 0, 0.025, 0.05, 0.075, and 0.1). The prepared samples were examined by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). XRD illustrates the pure rutile phase in all samples. The preferred orientation along [001] for pure sample convert to [101] direction with increasing doping content. Lattice constants increase with increasing doping content. The top view of FESEM images show the uniformly distributed nanorod arrays. The nanorods’ length decrease, and their diameters increase with increasing doping content. The nanorods start to bevel from its vertical direction after doping. The crystal size of TiO2 NRs with different manganese doping has calculated using the Williamson-Hall plot. The saturation magnetism appeared in pure titanium oxide has been attributed to the oxygen vacancies, while it changed to diluted magnetic semiconductor after doped with Mn.

Mn-site doping and its effect on inverted hysteresis and thermomagnetic irreversibility behavior of antiferromagnetic Mn5Si3 alloy

The structural and magnetic behavior of Mn-site doped intermetallic manganese silicide alloys of nominal compositions Mn5−xAxSi3 (x = 0.05, 0.1, 0.2 and A = Ni, Cr) have been investigated with a focus to the inverted hysteresis behavior and thermomagnetic irreversibility. Room temperature x-ray powder diffraction data confirm that all the doped alloys crystallize in hexagonal D88 type structure with space group P63/mcm. The doped alloys are found to show paramagnetic–collinear antiferromagnetic (AFM2)–noncollinear antiferromagnetic (AFM1) transitions during cooling from room temperature. A significant decrease in the critical values of both AFM1–AFM2 transition temperatures and fields have been observed with the increasing Ni/Cr concentration. Inverted hysteresis loop, field-induced arrest, and thermomagnetic arrest, the key features of the undoped Mn5Si3 alloy, are found to be significantly affected by the Mn-site doping and eventually vanishes with 4% doping.

The effect of Mn doping on nano structure and magnetic properties of MnxFe3-xO4-PEG/PVP/PVA based ferrogel

PVP/PVA based ferrogel was well fabricated using Freezing-Thawing method with MnxFe3-xO4-PEG magnetic nanoparticles as filler that was previously synthesized by simple coprecipitation method. This sample was confirmed by functional groups data from the Fourier Transform Infrared (FTIR). The manganese doping (x = 0, 0.5, 0.6, 0.7, and 0.8) was added to enhance the chemical and physical characteristics for increasing the application efficiency. Besides, polyethylene glycol (PEG) polymer was added to stabilize the magnetic nanoparticles through the hydrophilic characteristic. The XRD characterization showed that the crystal structure of MnxFe3-xO4-PEG nanoparticles corresponded to the magnetite phase with the highest peak at 2θ = 35.5° and had average particle sizes about 10.2 nm. This result was similar to the average crystal size characterized by the TEM instrument about 9.9 nm, and the secondary particle size analyzed by the SAXS instrument. By using the Two-Lognormal model, the secondary particle and primary particle sizes of the sample were successfully analyzed and resulted in the particle size of about 10 nm and 3.3 nm, respectively. To analyze the nanostructure of PVP/PVA hydrogels, meanwhile, the Beaucage and Teubner-Strey models were successfully used and resulted in the crystallite size and the average distance between the crystallite of PVP/PVA hydrogels which were approximately 8.8 and 38.6 nm, respectively. The saturation magnetization trend value of MnxFe3-xO4-PEG decreased by the addition of Mn and the particle size reduction. Furthermore, MnxFe3-xO4-PEG nanoparticles showed a superparamagnetic characteristic proven by its coercivity field and remnant magnetization approximated to zero. This result showed that the MnxFe3-xO4-PEG nanoparticles have the potency on some applications such as drug delivery applications and cellular imaging.

Double modification to effectively improve electrochemical performance of Co3O4 as Li-ion batteries anode

Transition metal oxide is one of the very potential electronic functional materials for lithium ion batteries, because of the low cost and high theoretical capacity. However, the low electron conductivity and poor cycle stability have limited its widely application. In this study, Co3-xMnxO4@C anode material with a uniform porous structure was successfully synthesized by a simple liquid precipitation method that was followed by thermal annealing. Dual strategy modification treatments were performed to obtain materials with the excellent electrochemical performance similar to those of the anode electrodes of lithium batteries. Manganese doping improved the stability, carbon coating enhanced the electrical conductivity, and the combination of the two tactics effectively improved the performance of the Co3O4 anodematerial.

Characterization, luminescence and dye adsorption study of manganese and samarium doped and co-doped zinc sulfide phosphors

Luminescent materials are widely used for various applications such as light-emitting diodes (LEDs), thermoluminescence dating, phosphor thermometry, as well as phosphors. Zinc sulfide is one of the most common phosphors due to its facile preparation and relatively low materials cost. Herein, manganese-doped, samarium-doped, and co-doped zinc sulfides were successfully synthesized by a precipitation method. XRD results showed no other crystalline phases observed in the synthesized products. The synchrotron-XRF confirmed the successful incorporation of Mn and Sm into the doped and co-doped samples, in which approximately 10% of the initial doping amount of Mn and 1% of the initial concentration of Sm3+ were found. XAS analysis revealed the oxidation state and local structure of the manganese dopant and the zinc in the ZnS host matrix. SEM and TEM showed the agglomeration of nanoparticles into secondary particles with irregular shapes. A comparative study on the photoluminescence characteristics of the pristine ZnS and its corresponding doped phosphors thoroughly ensued. The result showed that all the samples had identical defect-derived fluorescence peaks. However, the addition of Mn2+ ion had led to the extra emission at the wavelength around the value of 607 nm corresponding to the 4T1 to 6A1 transition within the Mn2+ activator. Interestingly, the samarium dopant shifted both the excitation and the emission maxima up to 11 nm and 10 nm, respectively. These shifts were not very high due to the limited incorporation of the samarium in the ZnS structure, as suggested by the synchrotron-XRF study. Our work, therefore, showed the prospects of tuning the bandgap energy of the transition doped ZnS by the addition of rare-earth ions. The N2 sorption isotherms revealed the relatively high specific BET surface areas (~171–196 m2/g). Apart from the luminescent applications, the present samples are also prospectively candidates for anionic-dye adsorption due to their dye selectivity.

Downshifting of highly energetic photons and energy transfer by Mn-doped perovskite CsPbCl3 nanocrystals in hybrid organic/silicon nanostructured solar cells

Abstract The downshifting of highly energetic photons in the ultraviolet region has the benefit of extending the spectral response and decreasing the thermalization effect in Si-related solar cells. Herein, we report low-cost hybrid organic/inorganic solar cells with minimized spectral losses with directly-deposited Mn-doped perovskite CsPbCl3 nanocrystals (NCs) on the surface of Si nanotips with PEDOT:PSS acting as the hole transporting and passivating layer. The CsPbCl3 NCs act as highly efficient radiative and non-radiative energy transfer centers. Manganese doping in CsPbCl3 NCs also drastically enhances photoluminescence quantum yields due to the charge transfer of photoinduced excitons from the CsPbCl3 host to the dopant Mn2+ centers. Finally, the Mn doped CsPbCl3 NCs enhance the cell properties and give a high power conversion efficiency of 13.48%.

The dispersion energy parameters, Linear and nonlinear optical properties of Transparent Mn:ZnO nanolayers

Throughout this research, the impact of Manganese doping on the optical characteristics of ZnO nanolayers was explained. The sol-gel spin coating technique has significant advantages due to the mixing of components on the atomic scale and provides excellent control over the composition that was employed to produce samples. The optical characteristics of Mn: ZnO nanolayers, were determined with the help of UV-VIS-NIR spectroscopy. The linear and nonlinear optical properties of nanolayers were investigated between 300 and 800 nm wavelengths. The dispersion properties of the samples were determined and interpreted in accordance with the single-oscillator model. The third-order nonlinear optical characteristics indicate a good correlation between theoretical and experimental results. These interesting results obtained by Mn-doping of ZnO showed a significant behavior for technological applications in electronic, optoelectronic devices and nonlinear optical applications.

Doping Induced Hierarchical Lattice Expansion of Cobalt Diselenide/Carbon Nanosheet Hybrid for Fast and Stable Sodium Storage

Transition metal chalcogenides have received considerable attention in sodium-ion batteries. However, their practical application is greatly hindered by the low conductivity and sluggish kinetics. Here, we report a hierarchical structure, featuring carbon nanosheets grafted on carbon nanofibers, as a substrate that supports cobalt diselenide (CoSe 2 @ carbon nanosheets [CNS]/carbon nanofiber [CNF]) to boost the conductivity and prevent electrode pulverization. Moreover, we demonstrate that manganese doping can be used to expand the sodium-ion diffusion channels in Co 1-x Mn x Se 2 and induce the synergistic lattice expansion of carbon nanosheets, alleviating the sluggish kinetics. Exploiting this strategy, the Co 1-x Mn x Se 2 @CNS/CNF with pre-sodium treatment can deliver a high specific energy density of 409.4 Wh kg −1 at 0.1 C when paired with Na 2 V 1.85 Fe 0.15 (PO 4 ) 3 /C cathode in a full cell. This work may provide insights into how doping induces hierarchical lattice expansion of transition metal chalcogenide/carbon hybrids to alleviate sluggish kinetics and enhance sodium storage. A CNS/CNF hierarchical structure is constructed to prevent electrode pulverization Mn doping can simultaneously achieve lattice expansion of CoSe 2 and carbon nanosheets This hierarchical lattice expansion improves sodium-ion storage capacity and stability Full Na-ion battery can deliver a high specific energy density of 409.4 Wh kg −1 at 0.1 C Transition metal chalcogenides (TMCs) with decent working potential and high reversible theoretical capacity have received considerable attention in sodium-ion batteries. Sun et al. demonstrate that doping engineering is a suitable strategy to manipulate the diffusion channel, which alleviates the sluggish kinetics in intercalation-based electrode materials.

Effect of manganese doping on the structural, morphological, optical, electrical, and magnetic properties of BaSnO3

ABO3 perovskites show unusual property modifications by proper substitution at the A and B sites. Polycrystalline perovskite BaSnO3 samples doped with different concentrations of manganese (BaSn1−xMnxO3) were synthesized by solid-state reaction method. Rietveld refinement of XRD analysis confirmed the structure and phase purity of the synthesized compound. Diamagnetic-to-paramagnetic transition and optical bandgap tuning indicate the substitutional effect of Mn in the host BaSnO3 lattice. The strong reverse saturable absorption of the synthesized samples makes them ideal candidate for optical limiting applications. The frequency and composition-dependent dielectric studies reveal that Mn-doped BaSn1−xMnxO3 can be used for high-frequency device applications. The cycling retention in the specific capacitance of 96.2% at a current density of 25 mA/g even after 2500 cycles in Mn-doped BaSnO3 electrode can be used in energy storage devices for supercapacitor applications.

Visible Light Photocatalysts Based on Manganese Doped TiO2 Integrated Within Monolithic Reduced Graphene Oxide/Polymer Porous Monolith

Abstract3D monolithic integrated photocatlysts were prepared by self‐assembly of graphene platelets decorated with manganese doped TiO2 nanoparticles. The self‐assembly was induced by chemical reduction at mild reaction conditions. The physico‐chemical properties of the photocatalysts were improved by addition of polymer nanoparticles within the 3D structures. The rGO presence in the nanostructures affected their light absorption capability, which was red shifted. As a result, the band gap dropped from 3.12 eV in Mn doped TiO2 to 2.8 eV in the monolithic composite made of rGO and TiO2. The photocatalysts were applied for the elimination of methylene blue (MB) from aqueous solutions, the degradation of which was monitored by the Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry. It was shown that (i) MB was completely eliminated from aqueous solution; (ii) all the adsorbed MB was photocatalytically degraded under visible light, giving rise to various smaller molecules as intermediate products of degradation; and (iii) one part of the MB was completely mineralized, demonstrated by the presence of final degradation products. These results indicate that the presented materials seem to be a powerful tool in water purification process with double impact. On one hand, it will allow re‐use of water and decrease of its consumption in the textile producing plants, and on the other hand, it will assure protection of the environment by elimination of the hazards.

Structural, magnetic and electrical properties along with antifungal activity & adsorption ability of cobalt doped manganese ferrite nanoparticles synthesized using combustion route

Ultrafine powders of Cobalt doped manganese ferrite with elemental composition Mn1-xCoxFe2O4 (x = 0.2, 0.4, 0.6, 0.8) were synthesized using combustion method. The formation of the pure cubic spinel phase of ferrite structure was confirmed using X-ray diffraction and Fourier transform infrared spectroscopy. Structural parameters such as lattice constant, X-ray density, mass density, porosity, and cell volume were seen to be greatly influenced by cobalt doping. The surface morphology of the nanocrystalline samples was studied using a scanning electron microscope. The particle size distribution was determined using a Transmission electron microscope and nanograins of the samples were found to have dimensions in the range 15 nm–30 nm. It also showed its dependence on the extent of cobalt inclusion. Variation of magnetization and magnetic moment as a function of magnetic field and temperature was investigated using a vibrating sample magnetometer (VSM). The parameters such as saturation magnetization ‘MS’ and inversion temperature TI were seen to depend upon Co+2 concentration. The variation dielectric constant ‘Ԑ’ as a function of frequency was studied. Antifungal activity of these ferrite nanoparticles against Rhizopus fungi was also investigated at room temperature. The antifungal activity was seen to increase with increasing Co+2 content in the manganese ferrite structure and hence cobalt doped manganese ferrites are proposed as a candidate material for industries manufacturing antifungal products. The adsorption studies were also investigated using Methylene dye as the adsorbate.

Coherent and para-equilibrium phase transformations in Mn-doped-LiFePO4 cathode materials: Implications for lithium ion battery performances

Abstract Due to the important similarities between olivine-LiFePO4 and olivine-LiMnPO4, manganese doping has drawn a lot of attention since it can improve the electronic and ionic conductivity of LiFePO4, hence enhance the electrochemical properties. The thermodynamic behavior of Mn-doped-LiFePO4 cathodes has been examined through the thermodynamic investigation of Li(MnyFe1-y)PO4-(MnyFe1-y)PO4 olivine joins. New sublattice thermodynamic models are proposed to describe the para-equilibrium in Li(MnyFe1-y)PO4-(MnyFe1-y)PO4 joins. Moreover, the elastic Gibbs energy approach extended in the large deformation regime is used to calculate the coherent miscibility gaps corresponding to (100) habit plane. The para-equilibrium and coherent miscibility gaps are calculated providing our prior estimated enthalpy of formation and the elastic constants of olivine compounds and enthalpy of mixing of binary sub-systems from first principles simulations based on Density Functional Theory (DFT). The experimental data on the para-equilibrium join is successfully reproduced, and the system is likely to experience the (100) coherent phase transformation. Our thermodynamic models of the Li(MnyFe1-y)PO4-(MnyFe1-y)PO4 join are able to describe most of the features of the electrochemical behavior of Li(MnyFe1-y)PO4 cathodes including the electrochemically driven phase diagram, open circuit voltage (OCV), asymmetry of charging/discharging processes, potential shift and favorable coherent phase transformation.

Manganese Doping Stabilizes Perovskite Light-Emitting Diodes by Reducing Ion Migration

Lead-halide perovskite light-emitting diodes have recently emerged as high-performance devices. However, they degrade rapidly. This degradation has been attributed to the mixed ionic–electronic nat...

Improvement of Power Conversion Efficiency of Quantum Dot-Sensitized Solar Cells by Doping of Manganese into a ZnS Passivation Layer and Cosensitization of Zinc-Porphyrin on a Modified Graphene Oxide/Nitrogen-Doped TiO2 Photoanode.

It is vital to acquire power conversion efficiencies comparable to other emerging solar cell technologies by making quantum dot-sensitized solar cells (QDSSCs) competitive. In this study, the effect of graphene oxide (GO), nitrogen, manganese, and a porphyrin compound on the performance of QDSSCs based on a TiO2/CdS/ZnS photoanode was investigated. First, adding GO and nitrogen into TiO2 has a conspicuous impact on the cell efficacy. Both these materials reduce the recombination rate and expand the specific surface area of TiO2 as well as dye loading, reinforcing cell efficiency value. The maximum power conversion efficiency of QDSSC with a GO N-doped photoelectrode was 2.52%. Second, by employing Mn2+ (5 and 10 wt %) doping of ZnS, we have succeeded in considerably improving cell performance (from 2.52 to 3.47%). The reason for this could be for the improvement of the passivation layer of ZnS by Mn2+ ions, bringing about to a smaller recombination of photoinjected electrons with either oxidized dye molecules or electrolyte at the surface of titanium dioxide. However, doping of 15 wt % Mn2+ had an opposite effect and somewhat declined the cell performance. Finally, a Zn-porphyrin dye was added to the CdS/ZnS by a cosensitization method, widening the light absorption range to the NIR (near-infrared region) (>700 nm), leading to the higher short-circuit current density (JSC) and cell efficacy. Utilizing an environmentally safe porphyrin compound into the structure of QDSSC has dramatically enhanced the cell efficacy to 4.62%, which is 40% higher than that of the result obtained from the TiO2/CdS/ZnS photoelectrode without porphyrin coating.

Structural features and energy harvester device applications of textured 0.675 PMN–0.325 PT piezoceramics

In the current study, textured lead magnesium niobate–lead titanate solid solution with composition 0.675Pb(Mg1/3Nb2/3)O3–0.325PbTiO3 (0.675PMN–0.325PT) has been fabricated with 0.7 mol% manganese (Mn) doping to enhance the soft character and the figure of merit (FOM). Random and textured PMN–PT plates were prepared by tape casting where 1 vol% plate-like barium titanate (BaTiO3) single-crystal templates were added to induce texture. A detailed structural investigation using scanning/transmission electron microscopy (STEM) and precession electron diffraction techniques has been conducted to establish the orientational relationship between the PMN–PT matrix and the BT templates. The FOM of textured and doped PMN–PT was found to increase for almost fourfold compared to random undoped case. Characterization of the energy harvesting (EH) performance of unimorph EH devices indicated an over twofold increase in the output power of the doped and textured case in comparison to the undoped and random PMN–PT ceramics.

Electron density modulation of GaN nanowires by manganese incorporation for highly high-rate Lithium-ion storage

Gallium nitride (GaN) has high theoretical capacity and low discharge platform. However, it still suffers from poor conductivity and unsatisfactory cycle performance in lithium-ion batteries (LIBs). In this work, the doped manganese (Mn) are realized in GaN nanowires through a simple and straight forward chemical vapor deposition (CVD) process. When the successful Mn doping was carefully examined in structural characterizations, it is discovered at the atomic level that the species of Mn dopants in GaN nanowires only exist in the feature of Mn+ rather than of metallic Mn, which can significantly promote the electrical conductivity and Li-ions transfer. The tested Mn doped GaN nanowire arrays electrode exhibit the capacity up to 780.3 mA h g−1 at 0.1 A g−1 after 100 cycles and 326.8 mA h g−1 at 5.0 A g−1 after 500 cycles, respectively. The tight and direct contact between Mn doped GaN nanowires and graphite layer provides ultrafast electronic transfer. Density functional theory (DFT) studies confirm that Mn covalent doping can generate the change of local atomic arrangement. Moreover, the electronic structure change significantly increase the electrical conductivity for the fast charge transfer efficiency. This covalent doping strategy for the electron densities regulation could boost the Li-ions storage performance for developing advanced electrode materials in energy storage and beyond.

Mechanism of Cu dopant in transition metal oxide Mn1.56Co(0.96-x)Ni0.48CuxO4+δ (0 ≤ x ≤ 0.2) thin films

To identify the substitution of Cu element for cations in transition metal oxide AB2O4 structure, we propose to investigate the structural, optical and magnetic properties of Cu-doped Mn1.56Co(0.96-x)Ni0.48CuxO4+δ films with 0 ≤ x ≤ 0.2. The X-ray diffraction of Mn1.56Co(0.96-x)Ni0.48CuxO4+δ films indicates good crystallization and cubic spinel structure. Raman spectra show two peaks of F2g and A1g vibration modes, and the peak position changes with Cu dopant. The transition temperatures TP1, TP2 shift towards lower temperature by Cu doping, and the saturation magnetization MS decreases monotonously. The results show that the substitution of Cu ions does not vary the crystal structure but changes the ratio of Mn3+/Mn4+. Our proposed way overcomes the difficulties to directly observe the atoms of Mn, Co, Ni, and Cu with closed sizes in microstructure, and it is instructive to further understand the conduction mechanism of doped manganese cobalt nickel oxides in theory.

A ZnS/CaZnOS Heterojunction for Efficient Mechanical-to-Optical Energy Conversion by Conduction Band Offset.

Actively collecting the mechanical energy by efficient conversion to other forms of energy such as light opens a new possibility of energy-saving, which is of pivotal significance for supplying potential solutions for the present energy crisis. Such energy conversion has shown promising applications in modern sensors, actuators, and energy harvesting. However, the implementation of such technologies is being hindered because most luminescent materials show weak and non-recoverable emissions under mechanical excitation. Herein, a new class of heterojunctioned ZnS/CaZnOS piezophotonic systems is presented, which displays highly reproducible mechanoluminescence (ML) with an unprecedented intensity of over two times higher than that of the widely used commercial ZnS (the state-of-the-art ML material). Density functional theory calculations reveal that the high-performance ML originates from efficient charge transfer and recombination through offset of the valence and conduction bands in the heterojunction interface region. By controlling the ZnS-to-CaZnOS ratio in conjunction with manganese (Mn2+ ) and lanthanide (Ln3+ ) doping, tunable ML across the full spectrum is activated by a small mechanical stimulus of 1 N (10 kPa). The findings demonstrate a novel strategy for constructing efficient ML materials by leveraging interface effects and ultimately promoting practical applications for ML.