Strong Mn2 Research Articles

Molarity Influenced Interesting Electrochromic Optical Modulation Peak Shift in Nebulized Spray Deposited Mn3O4 Films

Herein, we report the investigations on the electrochromic properties of nebulized-spray deposited Mn3O4 thin films in Na2SO4 aqueous solution as a function of molar concentration, for the first time. Phase analysis reveals that the films possess a tetragonal structure. From the Raman study, strong Mn2+ breathing vibration (in Mn–O) occurred in tetrahedral sites (of spinel Mn3O4). At 0.02 M, the film surface is covered with very-tiny particles with 84% highest optical transparency average. Both transmittance and absorbance related properties of electrochromic states are consider here, while introducing the notions of transmittance modulation (ΔT), absorbance modulation (ΔA), transmittance modulation efficiency (TME) and absorbance modulation efficiency (AME (or) coloration efficiency). When the concentration increases, the red shift was occurred at highest peaks of ΔT, ΔA, TME and AME with respect to the decrease in optical band gap. The maximum AME and TME of 25.064 cm2 C−1 (at 369.1 nm) and 17.542 cm2 C−1 (at 438.6 nm) were obtained for prepared samples. After the 100th cycle, the average AME (and TME) values in the UV and visible regions are decreases from 18.910 to 2.783 cm2 C−1 (2.884 to 1.060 cm2 C−1) and from 11.089 to 4.772 cm2 C−1 (11.346 to 4.684 cm2 C−1), respectively, indicating that the film is electrochromically active in the visible region even after the 100th cycle.

Efficient and tunable Mn2+ sensitized luminescence via energy transfer of a novel red phosphor Ca19Mn2(PO4)14: Eu2+ for white LED

The exploration of efficient and high-purity red phosphors is an urgent need in LED development. Due to the compact and compositional-tunable structure of whitlockite compound, manganese-based Ca19Mn2(PO4)14 is chosen as phosphor host for Eu2+ sensitization. Rietveld refinement, steady-state spectra, decay lifetime analysis and temperature-dependent emission spectra were investigated and clearly discussed. Under 360 nm excitation, Ca19Mn2(PO4)14: Eu2+ shows a strong Mn2+ sensitized emission at 655 nm with FWHM of 82 nm, benefiting from the short-distance-induced high-efficient Eu2 -Mn2+ energy transfer. Emission engineering of Ca19Mn2(PO4)14: Eu2+ is achieved by Sr2+ co-doping, leading to both tunable peak wavelength (ranging from 650 to 610 nm) and improved intensity (130% of original value). Moreover, Ca19Mn2(PO4)14: Eu2+ exhibits a promising thermal stability where only 40% of emission intensity is lost at 200 °C. Finally, we explored the working performance of the fabricated RGB phosphor-converted white LED. The present work indicates that Ca19Mn2(PO4)14: Eu2+ phosphor is of great potential as a promising and efficient red phosphor in phosphor-converted white LED.

Synthesis and optical properties of Mn2+-doped Cd–In–S colloidal nanocrystals

In recent years, light-emitting Mn2+-doped nanocrystals (NCs) have been widely studied because of their strong and stable Mn2+ d–d emission. Herein, highly efficient colloidal Mn2+-doped Cd–In–S NCs were prepared by a hot injection strategy. The as-prepared NCs have a cubic crystal structure of CdS host and exhibit strong Mn2+ emission. The photoluminescence (PL) intensity, PL position, and PL lifetime of this Mn2+ emission can be adjusted by changing the doping level of Mn2+. In particular, by tuning the amount of dopant, the emission color can be varied in the range of 601 nm to 643 nm, which is due to the coordination field environment of Mn2+ ions changed by the doping concentration. The PL intensity of Mn2+ is significantly enhanced by the ZnS shell coating, and the highest PL quantum yield can reach 56%, which is attributed to the removal of NCs surface-related defects by shell modification. A prototype LED was fabricated as well by using the as-prepared highly efficient Mn2+-doped Cd–In–S NCs as a color conversion material. The Mn2+-doped multicomponent semiconductor NCs reported here extend the availability of classical Mn2+-doped luminescent materials and provide alternatives for other applications requiring orange-red colloidal NCs.

Synthesis of high-efficient Mn2+ doped CsPbCl3 perovskite nanocrystals in toluene and surprised lattice ejection of dopants at mild temperature

Doping has been established as a powerful approach for endowing novel properties to perovskite nanocrystals (NCs).However, the fast formation of perovskites makes the fundamental understanding of doping processes in these NCs very rare. In the present work, a mild temperature (<100 °C) approach to produce Mn2+ doped CsPbCl3 (Mn:CsPbCl3) perovskite NCs in toluene is reported. The effects of the introduced Mn/Pb ratios in the raw materials as well as the temperature on the structure and photoluminescence (PL) properties of Mn:CsPbCl3 NCs were investigated systematically. The as-synthesized Mn:CsPbCl3 NCs shown a strong Mn2+ emission at 594 nm with a PL quantum yield (QY) of 52%, and the doping concentrations can be easily tailored from 1.8 atom% to 13.3 atom% by changed the Mn/Pb feed ratios. The study revealed that the reaction temperature plays a key role in Mn:CsPbCl3 NCs. Through elemental and microstructure characterization, it was surprisingly found that lattice ejection of Mn ions occurred at 100 °C. This result greatly enhances the understanding of the “basic process” of Mn2+doping in CsPbCl3 NCs, which provides some insights into the preparation of metal ion doped perovskite NCs.

Preparation of Mn2+‐Cu+ co‐doped P2O5–ZnO–Al2O3 glasses and their red fluorescence properties

AbstractTo make a Mn2+‐doped red glass phosphor that can be excited with ultraviolet (UV) light of light‐emitting diodes (LEDs), 60P2O5‐35ZnO‐5Al2O3‐8MnO‐xCu2O glasses (x = 0‐1.00) were prepared by a melt‐quenching method at 1200‐1400°C for 30‐180 minutes in atmospheric air, and the redox of Mn and Cu as well as fluorescence properties were investigated. The Mn2+ ion was not reduced and oxidized in the melting, quenching, and annealing processes. The valence of Cu in the glasses changed in the order of 0, 1+, and 2+ with the increase in the amount of Cu2O and in the melting temperature and time. In this study, a 60P2O5‐35ZnO‐5Al2O3‐8MnO‐0.10Cu2O glass melted at 1250°C for 90 minutes, having the highest Cu+ concentration, showed the strongest Mn2+ red fluorescence under the UV light at 275 nm. This strong Mn2+ red fluorescence has been caused by the energy transfer from excited Cu+ ions to Mn2+ ions.

High Br– Content CsPb(ClyBr1–y)3 Perovskite Nanocrystals with Strong Mn2+ Emission through Diverse Cation/Anion Exchange Engineering

The unification of tunable band edge (BE) emission and strong Mn2+ doping luminescence in all-inorganic cesium lead halide perovskite nanocrystals (NCs) CsPbX3 (X = Cl and Br) is of fundamental importance in fine tuning their optical properties. Herein, we demonstrate that benefiting from the differentiation of the cation/anion exchange rate, ZnBr2 and preformed CsPb1- xCl3: xMn2+ NCs can be used to obtain high Br- content Cs(Pb1- x- zZn z)(Cl yBr1- y)3: xMn2+ perovskite NCs with strong Mn2+ emission, and the Mn2+ substitution ratio can reach about 22%. More specifically, the fast anion exchange could be realized by the soluble halide precursors, leading to anion exchange within a few seconds as observed from the strong BE emission evolution, whereas the cation exchange instead generally required at least a few hours; moreover, their exchange mechanism and dynamics process have been evaluated. The Mn2+ emission intensity could be further varied by controlling the replacement of Mn2+ by Zn2+ with prolonged ion exchange reaction time. White light emission of the doped perovskite NCs via this cation/anion synergistic exchange strategy has been realized, which was also successfully demonstrated in a prototype white light-emitting diode (LED) device based on a commercially available 365 nm LED chip.

Improved Stability and Photoluminescence Yield of Mn2+-Doped CH3NH3PbCl3 Perovskite Nanocrystals

Organic–inorganic CH3NH3PbCl3 perovskite nanocrystals (PNCs) doped with Mn2+, CH3NH3PbxMn1−xCl3, have been successfully prepared using a reprecipitation method at room temperature. Structural and morphological characterizations reveal that the CH3NH3PbxMn1−xCl3 PNCs with cubic phase transforms from particles to cubes and increases in size from 16.2 ± 4.4 nm in average diameter to 25.3 ± 7.2 nm in cubic length after the addition of Mn2+ precursor. The CH3NH3PbxMn1−xCl3 PNCs exhibit a weak exciton emission at ~405 nm with a low absolute quantum yield (QY) of around 0.4%, but a strong Mn2+ dopant emission at ~610 nm with a high QY of around 15.2%, resulting from efficient energy transfer from the PNC host to the Mn2+ dopant via the 4T1→6A1 transition. In addition, the thermal and air stability of CH3NH3PbxMn1−xCl3 PNCs are improved due to the passivation with (3-aminopropyl) triethoxysilane (APTES), which is important for applications such as light emitting diodes (LEDs).

Picosecond Dynamics of Excitonic Magnetic Polarons in Colloidal Diffusion-Doped Cd(1-x)Mn(x)Se Quantum Dots.

Spontaneous magnetization is observed at zero magnetic field in photoexcited colloidal Cd(1-x)Mn(x)Se (x = 0.13) quantum dots (QDs) prepared by diffusion doping, reflecting strong Mn(2+)-exciton exchange coupling. The picosecond dynamics of this phenomenon, known as an excitonic magnetic polaron (EMP), are examined using a combination of time-resolved photoluminescence, magneto-photoluminescence, and Faraday rotation (TRFR) spectroscopies, in conjunction with continuous-wave absorption, magnetic circular dichroism (MCD), and magnetic circularly polarized photoluminescence (MCPL) spectroscopies. The data indicate that EMPs form with random magnetization orientations at zero external field, but their formation can be directed by an external magnetic field. After formation, however, external magnetic fields are unable to reorient the EMPs within the luminescence lifetime, implicating anisotropy in the EMP potential-energy surfaces. TRFR measurements in a transverse magnetic field reveal rapid (<5 ps) spin transfer from excitons to Mn(2+) followed by coherent EMP precession at the Mn(2+) Larmor frequency for over a nanosecond. A dynamical TRFR phase inversion is observed during EMP formation attributed to the large shifts in excitonic absorption energies during spontaneous magnetization. Partial optical orientation of the EMPs by resonant circularly polarized photoexcitation is also demonstrated. Collectively, these results highlight the extraordinary physical properties of colloidal diffusion-doped Cd(1-x)Mn(x)Se QDs that result from their unique combination of strong quantum confinement, large Mn(2+) concentrations, and relatively narrow size distributions. The insights gained from these measurements advance our understanding of spin dynamics and magnetic exchange in colloidal doped semiconductor nanostructures, with potential ramifications for future spin-based information technologies.

Mn-Substituted [Zn1−xMnxSe](DETA)0.5 (x = 0−0.3) Inorganic−Organic Hybrid Nanobelts: Synthesis, Electron Paramagnetic Resonance Spectroscopy, and Their Temperature- and Pressure-Dependent Optical Properties

Mn-substituted 1D [Zn1−xMnxSe](DETA)0.5(DETA = diethylenetriamine, x = 0−0.3) inorganic−organic hybrid nanobelts have been synthesized by a solvothermal reaction in a mixed solvent media. Strong Mn2+ internal transition (4T1 → 6A1) emission peaks at 585 nm (2.12 eV) are detected at room temperature photoluminescence (PL) spectra, and the highest emission intensity is obtained when the nominal Mn content x = 0.15. Temperature- and pressure-dependent photoluminescent properties as well as the electron paramagnetic resonance (EPR) spectra of [Zn1−xMnxSe](DETA)0.5 nanobelts have been studied for the first time. Temperature-dependent PL spectra show that the lower the temperature, the higher the intensity of the emission intensity. Under high pressure, a large red shift of Mn2+-related orange luminescence is observed and luminescent intensity is greatly decreased as the pressure increases to 10.5 GPa. Pressure dependence of the Mn2+ PL integrated intensity and energy have the same kink point at 2.54 GPa, which...

Cationic Substitution Sites in Mn2+-doped ZnS Nanoparticles

Mn2+-doped ZnS nanoparticles of average size 2.5±0.3 nm have been studied and characterized in the dopant concentration range 0.1–0.3% using XRD, EPR, XPS and photoluminescence methods. The experimental results obtained from these studies indicate that the doping of Mn2+ occurs primarily at the T d sites at low dopant concentration, causing the4T1(G) → 6A1(S) transition to take place in the host lattice; the observed decrease in the intensity of photoluminescence at high dopant concentration is due to the setting in of the strong Mn2+–Mn2+ interaction arising from cluster formation at the highly distorted sites near the particle surface.

Structure and Luminescence of 2D Dilute Magnetic Semiconductors: Cd1-xMnxSe·L0.5 (L = Diamines)

The two-dimensional (2D) dilute magnetic semiconductors Cd1-xMnxSe·L0.5 (L = ethylenediamine, or en, and 1,6-hexanediamine, or hda, x = 0−0.8) were synthesized in an autoclave at 120 °C. Ab initio structure solution from X-ray powder diffraction reveals the host compound CdSe·hda0.5 (space group, Pbca, a = 6.8852 Å, b = 6.7894 Å, c = 27.4113 Å) is structurally analogous to CdSe·en0.5, except for a subtle difference in alignment of aliphatic diamine ligandsthe hda molecule deflects from the c axis and inclines toward the b axis. CdSe·L0.5 shows well-defined UV absorption and emission peaks, which is attributed to a 2D exciton band edge transition due to size confinement effect in the c direction and the only photoemission level is the 2D exciton ground state with a long lifetime (7 μs) and intrinsic line width (177 meV) at room temperature. When Cd2+ is partly substituted by Mn2+, a strong Mn2+-related luminescence peak at 2.12 eV (584 nm) is obtained at room temperature, which can be assigned to Mn2+ internal transition (4T1 → 6A1); its excitation peak overlaps with the photoemission peak of the 2D exciton ground state which indicates that the Mn2+ emission is driven by the 2D exciton ground-state transition. For x = 0.02, the photoluminescence intensity of Cd1-xMnxSe·hda0.5 reaches maximum and enhances 28 times compared with that of Cd1-xMnxSe·en. When x < 0.05, the Mn2+ luminescence is a characteristic single-exponential decay process with a well-defined constant lifetime of 375 μs. Electron spin resonance spectra show that Mn2+ substitutes Cd2+ ion and forms a [MnSe3N] coordination tetrahedron and that there are isolated Mn2+ luminescence centers in Cd1-xMnxSe·hda0.5 (x < 0.05), which is the key factor for their stronger luminescence character compared to Cd1-xMnxSe·en0.5.

Synthesis, Structure, and Luminescence of 2D-Dilute Magnetic Semiconductors: Zn1-xMnxSe·0.5L (L = Diamines)

The two-dimension dilute magnetic semiconductors (2D-DMS) Zn1-xMnxSe·0.5L (L = ethylenediamine or en, 1,3-propanediamine or pda, 1,4-butanediamine or bda, and 1,6-hexanediamine or hda) and their host compounds ZnSe·0.5L were prepared by solvothermal reaction in solvent L at 190 °C. The powder X-ray diffraction patterns of ZnSe·0.5L are indexed as isomorphous orthorhombic lattices, whose constants c increase monotonically from L = en to L = hda. The orthorhombic lattice in ab plane of ZnSe·0.5en is a shrunken 2D superlattice (√3a×c) of the (110) plane of hexagonal ZnSe. When Zn2+ is partly substituted by Mn2+, Zn1-xMnxSe·0.5L become 2D-DMS. Their photoluminescence (PL) spectra show strong Mn2+-related emission peaks at 2.07 eV (600 nm). The Mn content dependence of PL intensity of Zn1-xMnxSe·0.5hda is especially studied, and high intensities are obtained when x < 0.2. For x ≈ 0.2, the PL intensities of Zn1-xMnxSe·0.5L increase from L = en to L = hda, which can be attributed to the formation of Zn/Mn−N bond...

Cathodoluminescence (CL) behaviour and crystal chemistry of apatite from rare-metal deposits

AbstractApatite samples from rare-metal mineralization were investigated by a combination of cathodoluminescence (CL) microscopy and spectroscopy, microchemical analysis and trace element analysis. Internal structures revealed by CL can be related to variations in the crystal chemistry and may sometimes reflect changes in the composition of the mineralizing fluids.Apatite from mineralization related to alkaline rocks and carbonatites (Type 1) typically exhibits relatively homogeneous blue and lilac/violet CL colours due to activation by trace quantities of rare earth element ions (Ce3+, Eu2+, Sm3+, Dy3+ and Nd3+). These results correlate with determined trace element abundances, which show strong light rare earth element (LREE) enrichment for this type of apatite. However, a simple quantitative correlation between emission intensities of REE3+/2+ and analysed element concentrations was not found.Apatite from P-rich altered granites, greisens, pegmatites and veins from Sn-W deposits (Type 2) shows strong Mn2+-activated yellow-greenish CL, partially with distinct oscillatory zoning. Variations in the intensity of the Mn2+-activated CL emission can be related either to varying Mn/Fe ratios (quenching of Mn activated CL by Fe) or to self-quenching effects in zones with high Mn contents (&gt;2.0 wt.%). The REE distribution patterns of apatite reflect the specific geological position of each sample and may serve as a “tracer” for the REE behaviour within the ore system. Although the REE contents are sometimes as high as several hundred parts per million, the spectral CL measurements do not exhibit typical REE emission lines because of dominance of the Mn emission. In these samples, REE-activated luminescence is only detectable by time-resolved laser-induced luminescence spectroscopy.Both types of apatite (Type 1 in the core and Type 2 in the rim) were found in single crystals from the Be deposit Ermakovka (Transbaikalia). This finding proves the existence of two stages of mineralization within this deposit.

The binding of metal ions to bovine factor IX.

The binding isotherms of Ca2+ and Mn2+ to bovine factor IX have been determined at pH 6.5 and pH 7.4, at 25 degrees C. At pH 7.4, at least 2 strong Ca2+ sites, with an average KDISS of 0.1 +/- 0.02 mM, are found. An additional 10 to 11 weaker Ca2+ binding sites, with an average KDISS of 1.3 +/- 0.2 mM are noted, at high levels of Ca2+. At pH 6.5, again at least 2 strong Ca2+ sites on factor IX are evident, with an average KDISS of 0.11 +/- 0.02 mM; but slightly fewer (7 to 8) weaker sites, with an average KDISS of 1.9 +/- 0.3 mM, are obtained. Qualitatively, the binding of Mn2+ to bovine factor IX appears similar to that of Ca2+. At pH 6.5, approximately 2 strong Mn2+ binding sites, with an average KDISS of 13 +/- 1.5 micrometer, and an additional 5 to 6 weak sites, with an average KDISS of 160 +/- 15 micrometer, are present. Manganese does not completely displace Ca2+; and Ca2+ does not completely displace Mn2+ from their respective binding sites. On the other hand, Tb3+ and Sm3+ readily displace Ca2+, at pH 6.5, from its sites on factor IX. The rate and extent of activation of bovine factor IX, by bovine factor XIa, is dependent on the Ca2+ concentration, up to concentrations of Ca2+ which saturate its effect on the system. Substitution of Sr2+ for Ca2+ leads to approximately 50% of the maximum rate of factor IXa formation, and final yield of factor IXa, in this activation system. Manganese does not substitute for Ca2+ in this activation, but does inhibit the stimulatory effect of Ca2+. Both Tb3+ and Sm3+ are effective inhibitors of Ca2+ in factor IX activation by factor XIa.