Effect Of Mn2 Research Articles

Effects of MnO doping on the electronic properties of zinc oxide: 406 GHz electron paramagnetic resonance spectroscopy and Newman superposition model analysis

MnO-doped ZnO ceramics have been synthesized through the conventional ceramic processing route. Mn2+ ions have been incorporated into the ZnO lattice within the limits of solid solubility. By using X-band-frequency and high-field electron paramagnetic resonance (EPR), we have resolved some of the main electronic transitions for the S = 5/2, I = 5/2 high-spin system and have determined accurately the EPR spin-Hamiltonian parameters. By combining data from crystallographic X-ray diffraction and EPR with the semi-empirical Newman superposition model, we have found the local configurational position of Mn2+ and have confirmed the symmetry of the lattice. The results presented in this contribution indicate that Mn ions substitute at Zn sites in ZnO. The effect of Mn2+ ions on the intrinsic defects becomes remarkable, thus the vacancy related intrinsic defect signals cannot be visible in the EPR spectrum. MnO doping affects the band gap energy of ZnO system which was confirmed via UV-Vis spectroscopy.

Effect of Mn2+ doping and SiO2 coating on magneto-optical properties of CoFe2O4 nano-particles

Co1−xMnxFe2O4 (x = 0.2, 0.4, 0.6, 0.8, 1.0) magnetic nanoparticles were prepared using a modified citrate gel method and fired at 500 °C for 2 h. The modified Stöber method was used for coating the magnetic nanoparticles with a silica shell. The effects of Mn2+ substitution and the method of preparation on the formation of crystalline phases, particle size, morphology and the optical and magnetic properties of the synthesized materials were investigated by XRD, SAED, HR-TEM, EDX, UV/VIS double-beam spectrophotometry and vibrating sample magnetometry. The average crystallite size of the synthesized nanoparticles was 18.6–43.9 nm. The maximum value of saturation magnetization (Ms) achieved was 65.668 emu/g for Mn0.2Co0.8Fe2O4 nanoparticles. Diffuse reflectance increased with an increase of Mn2+content and SiO2 shell. These coated magnetic nanoparticles are promising materials for application to magnetic sensors and biomedical nanodevices.

The Effects of Mn2+ Precursors on the Structure and Ozone Decomposition Activity of Cryptomelane-Type Manganese Oxide (OMS-2) Catalysts

The effects of Mn2+ precursors on the structure and ozone decomposition activity of cryptomelane-type manganese oxide (OMS-2) catalysts were investigated under high-humidity conditions. The OMS-2 catalysts were synthesized using a hydrothermal approach. Characterization of OMS-2 was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 physical adsorption, Raman spectroscopy, X-ray absorption fine structure (XAFS), H2 temperature-programmed reduction (H2-TPR), and inductively coupled plasma (ICP) spectroscopy. The OMS-2-Ac synthesized using MnAc2 as a Mn2+ precursor showed the best catalytic activity for ozone decomposition (∼80%) under RH = 90% and space velocity of 600000 h–1 and is a promising catalyst for purifying waste gases containing ozone under high-humidity conditions. Acetate groups could prevent the aggregation of manganese oxide particles, which may introduce more crystalline defects. On the basis of the characterization results, it is supposed that the greater sur...

Effect of Mn2+ ions on the enhancement red upconversion emission and energy transfer of Mn2+/Tm3+/Yb3+ tri-doped transparent glass-ceramics

The effects of Mn2+ ions on the enhancement red upconversion emission intensity of Mn2+/Tm3+/Yb3+ tri-doped transparent glass-ceramics were investigated. The ratio I698nm/I478nm significantly increases about ten-fold with the increase of Mn2+ concentrations up to 4.0mol.%. The red upconversion emission of Mn2+/Tm3+/Yb3+ tri-doped transparent glass-ceramics is greatly enhanced, due to constitution of the energy transfer bridge. The upconversion mechanism, the energy transfer and back energy transfer processes between the (1G4→3H6), (3F2→3H6) transitions of Tm3+ ions and the ∣2F7/2, 4T1〉→∣2F7/2, 6A1〉 transitions of Mn2+–Yb3+ dimer were discussed.

Photoluminescence properties and thermal stability of Eu2+ and Mn2+ co-doped BaSi3O4N2 phosphors

Non-rare-earth-metal Mn2+ and Eu2+ co-doped BaSi3O4N2 phosphors were synthesized by solid state reaction method. The effect of Mn2+ concentration upon photoluminescence behavior was investigated systematically. The specimens were efficiently excited from UV to visible region. The green emission of Eu2+ was greatly enhanced by Mn2+ due to the co-excitation and energy transfer between Mn2+ and Eu2+. The energy transfer probability from Mn2+ to Eu2+ depends strongly on the concentration of Mn2+ with the maximum at 6 mol%. Furthermore, corresponding quantum efficiency and thermal stability were dramatically improved. Through the assembly of as-prepared green phosphor, YAG:Ce3+ and Sr2Si5N8:Eu2+ phosphors with 460 nm InGaN chip, a broad range of white light was obtained bearing with color temperature of 3585–3650 K and color-rendering index of 95–98, exhibiting an attractive candidate for the application in phosphor converted light-emitting diodes (pc-LEDs).

Structural, optical and magnetic properties of Mn2+ doped ZnO-CdS composite nanopowder

Chemical precipitation method was used for the synthesis of Mn2+ doped ZnO-CdS composite nanopowder. The effect of Mn2+ doping was investigated on their structural, optical and magnetic properties. XRD pattern reveals the hexagonal phase of ZnO as well as CdS and the average crystallite size is found to be 18 nm. The morphological studies show non-uniformly distributed spherical like structures with little agglomeration. Crystal field and interelectronic repulsion parameters are evaluated from optical absorption study. EPR spectrum exhibits a well resolved sextet at g = 1.9924. By correlating optical and EPR studies, Mn2+ ions occupy octahedral sites in the host lattice which is also confirmed by PL analysis. From 1931 CIE chromaticity diagram, the prepared sample exhibits orange-red emission. IR spectrum confirms the existence of Zn-O and Cd-S vibrational modes. Room temperature ferromagnetism is observed in the prepared sample.

Effects of Mn2+ on the chrome‐free colored Ti/Zr‐based conversion coating on 6063 aluminum alloy

The conversion coating with golden color and improved corrosion resistance had been prepared by adding Mn2+ in the Ti/Zr conversion coating solution. Comparing with that of conversion coating without Mn2+, the optimal treatment time of this conversion coating was much shorter and the corrosion resistance was obviously improved. The effect of Mn2+ on the formation of golden Ti/Zr conversion coating was thoroughly investigated by means of energy dispersive X‐ray spectroscopy, SEM, XPS, and Raman and electrochemical workstation. The results showed that the conversion coating had a double‐layer structure: the outer layer consisted of the metal‐organic complex and the inner layer was mainly made up of Na3AlF6. Mn2+ was oxidized into MnOOH in solution and precipitated on the substrate surface which provided the nucleus to Na3AlF6 crystal and accelerated Na3AlF6 crystal formation and also made the microstructure of conversion coating change to the cubic. The mechanism of the formation of the conversion coating can be deemed as nucleation, growth of Na3AlF6 crystal, and formation of metal‐organic complex. Copyright © 2015 John Wiley & Sons, Ltd.

Effect of Mn2+ ions on the enhancement upconversion emission and energy transfer of Mn2+/Tb3+/Yb3+ tri-doped transparent glass-ceramics

The effect of Mn2+ on the enhancement upconversion (UC) emission and energy transfer of Mn2+/Tb3+/Yb3+ tri-doped SiO2–AlF3–BaF2–TiO2–LaF3 transparent glass-ceramics under excitation 980nm LD were successfully investigated. The UC emission intensity bands centered at 493, 548, 593 and 622nm corresponding to (5D4→7FJ(J=6, 5, 4 and 3)) transitions of Tb3+ were significantly increased with the increase of the Mn2+ concentrations and reaches its maximum at 2.0mol%, then decreases due to the self-quenching effect. Particularly, the UC emission intensity bands centered at 656nm (5D4→7FJ(J=2, 1 and 0)) of Tb3+ was strongly increased about 15-fold with the increase of Mn2+ concentration up to 2.0mol%. The upconversion mechanism and the energy transfer processes from (4T1→6A1) transition of Mn2+ to 5D4→7FJ(J=6, 5, 4, 3, 2, 1 and 0) transitions of Tb3+ were discussed.

Preparation and Optical Property of ZnS:Mn/XO<sub>2</sub> (X=Ti, Si) Nanoparticles with Core/Shell Structure

In this paper, Mn2+ doped ZnS (ZnS:Mn) nanoparticles were prepared by co-precipitation method. And then different thickness of TiO2 and SiO2 inorganic shell were coated on prepared ZnS:Mn through the hydrolysis reaction of tetrabutyl titanate (TBOT) and tetraethyl orthosilicate (TEOS). ZnS:Mn crystal and core/shell structure were described by X-ray diffraction (XRD) and scanning electron microscope (SEM). Optical property of all ZnS:Mn/XO2 (X=Ti, Si) nanoparticles were investigated by photoluminescence (PL) spectrometer. The effect of Mn2+ concentration and XO2 (X=Ti, Si) shell thickness on luminescence intensity of ZnS:Mn/XO2 was studied. The results showed that with TiO2 and SiO2 shell thickening, Mn2+ emission of ZnS:Mn/XO2 samples increased first and then decreased. When the thickness of inorganic shell (molar ratio of shell and core amount) reached to 0.5 (TiO2) and 1.0 (SiO2), the optimal luminescence intensity was obtained. The emission of ZnS:Mn/TiO2 and ZnS:Mn/SiO2 was 2.0 and 1.5 times more in intensity than that of uncoated ZnS: Mn, respectively.

Mn2@Si15: the smallest triple ring tubular silicon cluster.

The smallest triple ring tubular silicon cluster Mn2@Si15 is reported for the first time. Theoretical structural identification shows that the Mn2@Si15 tubular structure whose triple ring is composed by three five-membered Si rings in anti-prism motif, is stable in high symmetry (D5h) and singlet ground state ((1)A1'). The dimer Mn2 is placed inside the tubular along the C5 axis, and the Mn dopant form single Si-Mn bonds with Si skeleton, whereas the Mn-Mn is characterized as a triple bond. The effect of Mn2 on the stability of the Si15 triple ring structure arises from strong orbital overlap of Mn2 with Si15.

Pretreatment of cyanided tailings by catalytic ozonation with Mn2 +/O3

The increasing amount of cyanided tailings produced as a by-product has gained significant attention in recent years because of the rapid development of the gold industry and extensive exploitation of gold mineral resources. The effective use of these secondary resources is becoming an important and urgent problem for all environmental protection staff. Manganese-catalyzed ozonation for the pre-oxidation of cyanided tailings was studied and the effects of Mn2+ dosage, initial sulfuric acid concentration, ozone volume flow, temperature and agitation speed on pretreatment were examined. The optimum reaction conditions were observed to be: ore pulp density 2.5%, agitation speed 700r/min, temperature 60°C, Mn2+ dosage 40g/L, ozone volume flow 80L/hr, initial sulfuric acid concentration 1mol/L, and reaction time 6hr. Under these conditions, the leaching rate of Fe and weight loss could reach 94.85% and 48.89% respectively. The leaching process of cyanided tailings by Mn2+/O3 was analyzed, and it was found that the leaching of pyrite depends on synergetic oxidation by high-valent manganese and O3, in which the former played an important part.

Effect of Mn (II) on quartz flotation using dodecylamine as collector

Quartz is, in most cases, the major gangue mineral found in the manganese ore. Mn iron, dissolved from the surface of ore, will determine the interfacial properties of the particles and, thus, their flotation behavior. In this work, the effect of Mn2+ on quartz flotation was investigated through flotation tests. It was found that quartz can be depressed with Mn2+ and floated with dodecylamine in the pH region 7-8. In order to prove the validity of the findings, UV spectrophotometry, FTIR and SEM-EDS were carried out. UV spectrophotometry tests results show that Mn2+ can competitive adsorb with RNH3 (+) in the surface of quartz at acidic and neutral pH values. The FTIR measurements and SEM-EDS analysis indicate that Mn2+ forms precipitation and adsorbs on the negatively charged quartz surface, it induces quartz recovery dropping in alkaline pH. Furthermore, in the case of sodium hexametaphosphate (SH), sodium silicate or citric acid, the effects of Mn2+ were also studied. This depression in the given Mn2+ did not disappear. Citric acid is an appropriate modifier to separate quartz depressed by Mn2+ from other ores at pH 7.

Effect of Mn2+ ions on the enhancement red upconversion emission of Mn2+/Er3+/Yb3+ tri-doped in transparent glass-ceramics

Abstract The glass and glass-ceramics samples with composition of 50SiO2–10AlF3–(30−x)BaF2–5TiO2–3.95LaF3– xMnCO3–0.05ErF3–1YbF3 (in mol%, x=0, 0.5, 0.8, 1.0, and 1.2) were prepared using the conventional quenching techniques. The effects of Mn2+ ions on the enhancement red upconversion emission of Mn2+/Er3+/Yb3+ tri-doped transparent glass-ceramics under the changing of heat treatment temperatures and concentrations of Mn2+ ions were investigated. The structural investigation carried out by X-ray diffraction (XRD), and transmission electron microscopy evidenced the formation of cubic Ba2LaF7 nanocrystals. The efficiency upconversion emission of Mn2+/Er3+/Yb3+ tri-doped was observed in the glass-ceramics. The upconversion mechanism and energy transfer between Mn2+–Yb3+ dimer and Er3+ ions were investigated.

WITHDRAWN: Effects of Mn2+ doping on structural, morphological, optical and catalytic properties of magnetic CoFe2O4 nanoparticles prepared by urea-assisted auto combustion method

WITHDRAWN: Effects of Mn2+ doping on structural, morphological, optical and catalytic properties of magnetic CoFe2O4 nanoparticles prepared by urea-assisted auto combustion method

Effect of Mn2+, Co2+ and H2O2 on biomass and lipids of the green microalga Chlorella vulgaris as a potential candidate for biodiesel production

The present study examined the effect of heavy metals (Mn2+ and Co2+) and hydrogen peroxide (H2O2) on biomass, lipid content and lipid productivity of Chlorella vulgaris. Manganese chloride at 2 μM, 10 μM and 12 μM increased the lipid content significantly by 14 %, 16 % and 15 %, respectively, above the corresponding controls after 8 days of incubation, resulting in a significant (18 %) increase in lipid productivity with respect to the control at 12 μM manganese chloride. All applied concentrations of cobalt nitrate increased the lipid content up to 25 % more than the corresponding controls. The optimum concentration of cobalt nitrate for high lipid productivity was 2.5 μM, which resulted in a 22 % increase in lipid productivity over the control. Furthermore, lipid productivity was increased significantly by 29 % over the control when 4 mM hydrogen peroxide was included in the culture medium. Additionally, the proportion of total saturated fatty acids extracted from Chlorella vulgaris treated with 12 μM manganese chloride, 2.5 μM cobalt nitrate and 4 mM hydrogen peroxide ranged between 40 % and 45 % of total fatty acids. The present study concluded that heavy metals and oxidative stress efficiently increased the lipid productivity of the promising biodiesel feedstock chlorophyte Chlorella vulgaris. In addition, the type and proportion of individual fatty acids meet the biodiesel standards.

Magnetic and optical properties of Cr/Mn-co-doped Li1.72Na0.28Ge4O9 single crystals

Li1.72Na0.28Ge4O9 single crystal co-doped with Cr3+ (0.1mol%) and Mn2+ (0.1mol%) has been prepared by the Czochralski method. The electron paramagnetic resonance reveals presence of Cr3+ and Cr3+–Li+/Na+ pairs. Photoluminescence spectra show the sharp R1 and R2 emissions bands at 688–697nm due to the 2Eg→4A2g transition of Cr3+. They consist of three and two components, respectively. No emission from Mn2+ is observed because of energy transfer to the 2Eg state of Cr3+. An effect of Mn2+ in the co-doped crystals is discussed.

Effects of Mn2+ on the electrical resistance of electrolessly plated Ni–P thin-film and its application as embedded resistor

The effects of manganese sulfate monohydrate (denoted as MSM) on the properties of electroless Ni–P thin-film were investigated. The properties of Ni–P thin-film were examined by means of atomic force microscopy (AFM), cyclic voltammetry, scanning electron microscopy (SEM), X-ray diffraction, energy-dispersive X-ray spectrometer and X-ray photoelectron spectroscopy. AFM and SEM results showed that MSM had significant influences on the morphology, including the formation of smaller nodules, nano-size particles boundaries on both surface and inside of nodules. Due to the specific topologies, the resistance of Ni–P thin-film deposited with MSM was increased. Based on the characterization results, we summarized that the Mn2+ or Mn2+-compound were primarily confirmed to act as the stabilizer in Ni–P electroless process. Moreover, the verification test for Ni–P thin-film in application as embedded resistor was carried out through electrical, thermal stability examination by means of current–voltage (I–V), temperature coefficient of resistance and thermal shock tests, respectively. Experiment results demonstrated the Ni–P thin-film deposited with MSM is qualified for embedded resistors.

Effect of Mn2+ Doping on Structural, Morphological and Optical Properties of ZnS Nanoparticles by Chemical Co-Precipitation Method

Zinc Sulphide (ZnS) nanoparticles doped with different concentrations of Mn 2+ (0%, 2%, 4%, 6%, 8%, 10%) have been synthesized by chemical co-precipitation method using polyvinyl alcohol (PVA) as a capping agent to control the particle growth. The structural characterizations of as synthesized nanoparticles are determined by X-ray diffraction (XRD) which showed cubic zinc blende structures with average crystallite sizes of the range 2.3 nm - 2.1 nm. There is no phase transformation due to Mn 2+ doping and this characteristic has been observed in all the synthesized powder. Scanning electron microscopy (SEM) and energy dispersive X- ray (EDX) analysis show the morphology and elemental analysis of as synthesized nanoparticles.TEM images confirms the spherical shape of the nanoparticles. HRTEM and SAED images show the crystalline nature and confirm the cubic nature of ZnS nanoparticles. Absorption study has been carried out by using UV-Vis spectrophotometer to determine the band gap of ZnS:Mn nanoparticles and they showed a blue shift with respect to the bulk. The effect of Mn 2+ substitution on the photoluminescence properties of doped samples is also studied and doped ZnS:Mn showed enhanced luminescence property compared with that of the undoped ZnS nanoparticles. Radius of the synthesized nanoparticles has been evaluated from the absorption spectrum by using the Effective Mass Approximation (EMA) formula. Fourier Transform Infrared Spectra (FTIR) is recorded in an FTIR spectrometer to verify the presence and effect of capping agent.

Short-term effects of Mn2+ on elongation growth and H+ -extrusion in Zea mays L. coleoptile segments

The effect of 10<sup>-2</sup>-10<sup>-6</sup> M Mn<sup>+2</sup> on the growth and acidification of the incubation medium by <em>Zea mays</em> L. coleoptile segments was studied. It is shown that 10<sup>-5</sup>M manganese stimulated growth (in comparison to a control without Mn<sup>+2</sup>) while concentrations from 10<sup>-2</sup> to 10<sup>-4</sup>M clearly inhibited it. It was also found that manganese at the studied concentration range significantly inhibited acidification of the incubation medium. Auxin, at a concentration of 10<sup>-5</sup>M, reversed the inhibitory effect of Mn<sup>+2</sup> (with the exception of 10<sup>-2</sup>M) on the growth and acidification of the incubation medium by <em>Zea mays</em> L. coleoptile segments.

Manganese-induced infidelity of DNA synthesis as a possible cause of manganism

The impact of the 8 most common bivalent metal cations (Mg2+, Mn2+, Co2+, Cd2+, Zn2+, Ni2+, Ca2+, Cu2+) on the operation of the whole complex of DNA polymerases in mice brain cell extracts was tested. A decrease in the fidelity of the DNA synthesis was observed in the presence of several metals; among them, Mn2+ caused the most significant effect. It was also demonstrated that this effect was mainly due to the DNA polymerase iota (Pol iota) activity. It is well known that occupational or environmental exposure to excessive Mn could lead to development of neurodegenerative diseases (e.g., manganism). However, the molecular mechanism underlying these pathologies is still unknown. Our results suggest that the neurotoxic effect of Mn2+ may be associated with local activation of highly error-prone Pol iota that increases incorrect DNA synthesis at elevated concentrations of this metal.