Synthesis and DFT Calculation of a Four- coordinated Manganese Compound Mn_2(BPTC)

A new four-coordinated manganese compound Mn2（BPTC） （BPTC =- biphenyl- 2,4,4＇,6-tetracarboxylate） with flu topology net was synthesized under hydrothermal conditions. Single-crystal X-ray diffraction analysis confirms its crystal belongs to the monoclinic system, space group C2/c with a = 12.2092（11）, b = 14.6932（9）, c = 8.9998（10） A, t= 108.256（12）°, Z= 4, V= 1533.2（2） A3, Dc = 1.889 mg/m3,μ = 1.69, F（O00） = 864, the final R = 0.063 and wR = 0.201 for 1407 observed reflections （I 〉 20（/））. UV-Vis absorption spectrum shows the title compound has a strong absorption at 326 and 238 nm and the optical diffuse reflectance determination shows the band gap of the title compound is 3.15 eV. The theory calculation elucidated that the UV absorptions of the title compound mainly arise from the electron transition from bonding orbitals of BPTC4- ligand to the empty orbitals of BPTC4- and Mn（II） ions.

Extraction of manganese and zinc from their compound ore by reductive acid leaching

Comprehensive utilization of low grade manganese?zinc compound ore containing lead and silver with a method of reductive acid leaching was studied.According to theφ?pH diagram of Mn?Zn?H2O system,Mn and Zn can be leached simultaneously in the pH range of?2to5.61.The results showed that both hydrogen peroxide and sucrose were effective reductants which could intensify the simultaneous leaching of Mn and Zn into leachate as well as enrich Pb and Ag in the residue.95.88%of Mn and99.23%of Zn were extracted when the compound ore was leached with hydrogen peroxide in sulfuric acid media,meanwhile the contents of Pb and Ag in the residue were enriched to13.21%and489.36g/t,respectively.When sucrose was used as the reductant,the leaching efficiencies of Mn and Zn separately achieved98.26%and99.62%,and contents of Pb and Ag in the residue were as high as13.92%and517.87g/t,respectively.

Synthesis and Crystal Structure of a Salicylaldehyde Ethylene Diamine Schiff Base Manganese (Ⅲ) Complex

The title compound, [Mn(salen)(salicyl)]?.5H2O ( H2salen = N, N?ethylenebis- (salicylideneaminato), Hsalicyl = salicylaldehyde), has been obtained from the reaction system containing (o-HOC6H4CH=NCH2)2, o-HOC6H4CHO and Mn(ClO4)2?H2O in EtOH solvent and structurally characterized. It crystallizes in the monoclinic, space group P21/c with a = 13.0548(4), b = 13.9254(4), c = 11.6630(1) ? b = 105.199(2)? V = 2046.09(9) ?, Z = 4, C23H22MnN2O5.5, Mr = 469.37, Dc = 1.524 g/cm3, F(000) = 972, m = 0.687mm-1 . R = 0.0630 and wR = 0.1142 for 1901 observed reflections with I >2(I). The Mn(Ⅲ) is coordinated by N(1), N(2), O(1) and O(2) of the Schiff base ligand and phenolate O atom of salicylaldehyde with O(3)Mn distance of 2.050(4) , forming a relatively rare five-coordinate square-pyramidal structure.

Synthesis and Crystal Structure of a New Mn_8 Compound with Tripodal Ligand

A new manganese compound [Mn8（tmp）2（Htmp）4（（CH3）3CCO2）4（py）2Cl2]·2py （1·2py, H3tmp = 1,1,1-tri（hydroxymethyl）propane, py = pyramid） has been synthesized and its structure was characterized by IR, elemental analysis and X-ray diffraction. Compound 1 belongs to the triclinic system, space group P1 with a = 13.378（5）, b = 14.334（5）, c = 15.012（6） , α = 107.637（5）, β = 95.635（3）, γ = 92.825（4）°, V = 2720.7（17） 3, Z = 1, C76H124N4O26Cl2Mn8, Mr = 2022.23, Dc = 1.234 Mg/m3, μ = 1.007 mm-1, F（000） = 1052, T = 293（2） K, the final R = 0.0755 and wR = 0.2163 for all 6463 observed reflections （I 〉 2σ（I））. X-ray analysis shows that the core of 1 contains a [Mn8] mixed-valence rod-like unit consisting of six edge-sharing triangles （Mn3）, each of which is bridged by a μ3-oxygen atom.

Syntheses，Structures and Properties of Some New Composition Perovskite Compounds：Sr0．6Bi0．4FeO2．7，Sr1－xBixFeO3－y and Ba1．5Pt0．5Mn2O6

New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure of Sr0.6Bi0.4FeO2.7has been determined by X-ray single crystal diffraction,and the data of neutron powder diffraction collected at both room temperature and elevated temperature(380℃).The compound Sr0.6Bi0.4FeO2.7 crystallizes in the cubic space group of Pm3m with Z=1,a=3.9330(6) at room temperature,a=3.9498(6)A at 380℃.The magnetic structure from the neutron powder diffraction data collected at room temperature is consistent with a simple G-type antiferromagnetism and has a magnetic moment of 4.98 μB per Fe atom.The structures of Sr1-xBixFeO3-y with x other than 0.4 were also refined from the X-ray powder diffraction data.The data were consistent with a tetragonal cell when x=0.1,a rhombohedral cell when x= 0.9,and a cubic cell for x=0.2～0.8.From single crystal X-ray diffraction data,Ba1.5Pt0.5Mn2O6 crystallizes in hexagonal space group of P63mc with a= 5.7722 (6),c=4.4504(9),V=128.42(2),Z=1.The Sr(1-x)BixFeO(3-y)are found to be a good electronic and ionic conductor.

Interface Engineering of NixSy@MnOxHy Nanorods to Efficiently Enhance Overall-Water-Splitting Activity and Stability

Exploring highly active and stable transition metal-based bifunctional electrocatalysts has recently attracted extensive research interests for achieving high inherent activity, abundant exposed active sites, rapid mass transfer, and strong structure stability for overall water splitting. Herein, an interface engineering coupled with shell-protection strategy was applied to construct three-dimensional(3D) core-shell NixSy@MnOxHy heterostructure nanorods grown on nickel foam(NixSy@MnOxHy/NF) as a bifunctional electrocatalyst. NixSy@MnOxHy/NF was synthesized via a facile hydrothermal reaction followed by an electrodeposition process. The X-ray absorption fine structure spectra reveal that abundant Mn-S bonds connect the heterostructure interfaces of N ixSy@MnOxHy, leading to a strong electronic interaction, which improves the intrinsic activities of hydrogen evolution reaction and oxygen evolution reaction(OER). Besides, as an efficient protective shell, the MnOxHy dramatically inhibits the electrochemical corrosion of the electrocatalyst at high current densities, which remarkably enhances the stability at high potentials. Furthermore, the 3D nanorod structure not only exposes enriched active sites, but also accelerates the electrolyte diffusion and bubble desorption. Therefore, NixSy@MnOxHy/NF exhibits exceptional bifunctional activity and stability for overall water splitting, with low overpotentials of 326 and 356 mV for OER at 100 and 500 mA cm^(–2), respectively, along with high stability of 150 h at 100 mA cm^(–2). Furthermore, for overall water splitting, it presents a low cell voltage of 1.529 V at 10 mA cm^(–2), accompanied by excellent stability at 100 mA cm^(–2) for 100 h. This work sheds a light on exploring highly active and stable bifunctional electrocatalysts by the interface engineering coupled with shell-protection strategy.

Synthesis, Structure and Magnetic Properties of a Linear Trinuclear Mn(II) Complex with a Multifunctional Group Ligand

By use of a new ligand containing both salicylic acid moiety and salicylaldehyde Schiff base moiety, 5-（2-hydroxybenzylideneamino）-2-hydroxybenzoic acid （H3L）, a linear trinuclear Mn（II） complex was prepared. This complex crystallizes in triclinic, space group P1 with a = 12.0196（7）, b = 13.7440（13）, c = 15.7554（14） , α = 111.529（3）, β = 96.691（2）, γ = 94.802（2）o, C96H100Mn3N6O32, Mr = 2014.64, V = 2382.0（3） 3, Z = 1, μ = 0.478, Dc = 1.404 g/cm3, F（000） = 1049, R = 0.0554 and wR = 0.1610 for 8973 observed reflections （I 〉 2σ（I））. The complex consists of a trinuclear cluster and two solvate ethanol molecules. Three linearly disposed Mn atoms, with an inversion center on the central one, are bridged by six carboxylate groups from six bulky mono-anionic ligands （H2L-）, and the octahedral coordination spheres for each of the metal centers are thus formed, with the aid of additional ligation of two small molecules （ethanol and water） to both ends. The magnetic properties of the title complex are also included in this paper.

Electrochemical properties of LiNi_(0.5)Mn_(1.3)Ti_(0.2)O_4/Li_4Ti_5O_(12)cells

Spinel compounds LiNi0.5Mn1.3Ti0.2O4（LNMTO） and Li4Ti5O12 （LTO） were synthesized by different methods. The particle sizes of LNMTO and LTO are 0.5-2 and 0.5-0.8 μm, respectively. The LNMTO/LTO cell exhibits better electrochemical properties at both a low current rate of 0.2C and a high current rate of 1C. When the specific capacity was determined based on the mass of the LNMTO cathode, the LNMTO/LTO cell delivered 137 mA.h.g-1 at 0.2C and 118.2 mA-h-g-l at 1C, and the corresponding capacity retentions after 30 cycles are 88.5% and 92.4%, respectively.

Magnetic and electric characteristics and abnormality of low-temperature resistivity in La_(0.67–x)Er_xSr_(0.33)MnO_3(0.00≤x≤0.20) system

M-T curves, ρ-T curves, and MR-T curves of La0.67-xErxSr0.33MnO3(x=0.00, 0.10, 0.20) system were studied by experiments. The experiments showed that: with increasing the doping amount, the magnetic structure of the system transformed from long-range ferromagnetic ordering to spin-cluster glass state, and M-T curves bent up in the extremely low temperature range; the resistivity of the system increased with increasing doping amount and exhibited the minimum phenomenon of low-temperature resistivity. The variation of the magnetic and electric properties came from the extra magnetic coupling induced by the doping and from the Kondo effect induced by the lattice distortion and local magnetic moments which was similar to that induced by the scattering of magnetic impurities on electron spins. © 2009 The Chinese Society of Rare Earths.

Ti Anode with Ti-Mn Coating

A new type anode, Ti anode with Ti-Mn coating, has been used to prepare EMD (Electrolytic Manganese Dioxide) by some Chinese manufacturers for 4 years. The industry test shows that this anode has such characteristics as sturdy, light, fine mechanical performance, very high passivation resistance and corrosion resistance. The passivation of this anode is discussed and the results show that this anode is better than the pure titanium anode in the EMD industry.

Temperature-dependent Syntheses of Two Manganese(Ⅱ) Coordination Compounds Based on an Ether-bridged Tetracarbolylic Acid

0D dinuclear manganese(Ⅱ)coordination compound and 1D chain manganese(Ⅱ)coordination polymer,namely[Mn2(μ-L)(phen)4]·4H2O(1)and{[Mn2(μ5-L)(phen)2]·H2O}n(2),have been constructed hydrothermally using H4L(H4L=2,3,3΄,4΄-diphenyl ether tetracarboxylic acid),phen(phen=1,10-phenanthroline),and manganese chloride at 120 and 160°C,respectively.The products were isolated as stable crystalline solids and were characterized by IR spectra,elemental analyses,thermogravimetric analyses(TGA),and single-crystal X-ray diffraction analyses.Single-crystal X-ray diffraction analyses revealed that two compounds crystallize in the triclinic or monoclinic system,space group P1 or P21/c.Compound 1 discloses a discrete dimeric structure,which is assembled into a 3D supramolecular framework through O-H…O hydrogen bond.Compound 2 has a chain structure.Structural differences between compounds 1 and 2 are attributed to the different reaction temperature.Magnetic studies for compound 2 demonstrate an antiferromagnetic coupling between the adjacent Mn(Ⅱ)centers.

Fluorescence enhancement of single-phase red-blue emit-ting Ba_3MgSi_2O_8:Eu^(2+),Mn^(2+) phosphors via Dy^(3+) addition for plant cultivation

Fluorescence enhancement of red and blue concurrently emitting Ba3MgSi2O8:Eu2+,Mn2+ phosphors for plant cultivation has been investigated by Dy3+ addition.The Ba3MgSi2O8:Eu2+,Mn2+,Dy3+(BMS-EMD) phosphors have two-color emissions at the wavelength peak values of 437 nm and 620 nm at the excitation of 350 nm.The two emission bands are coincident with the absorption spectrum for photosynthesis of plants.An obvious enhancement effect has been observed upon addition of Dy3+ with amount of 0.03 mol%,in which the ...

Growth and characterization of high-quality Mn-doped LiAlO_2 single crystal

The growth of a Mn-doped LiAlO_2 single crystal by the Czochralski（CZ） method and the characterization of its spectroscopy and thermoluminescence（TL） are presented.The X-ray rocking curve and chemical etching analysis show that the as-grown crystal has good crystallinity.The full-width at half-maximum （FWHM） of the LiAlO_2（200）ωrocking curve is 23.2 arcsec and the etching pits density of the（100） plane is（1.6-4.0）×10~4 cm^（-2）.The transmission spectrum indicates that the crystal is highly transparent in the 200-1500-nm wavelength range.The emission spectrum of the crystal consists of a peak around 579 nm when excited with 428-nm light.The TL spectra show that the LiAlO_2：Mn crystal has glow peaks at 150 and 172℃.The change of TL characteristics of the crystal before and after thermal annealing in the air is discussed,and the effect of annealing and irradiation on the evolution of defect types is analyzed.

Spectral properties and energy transfer in YAlO_3 crystals doped with Ce ions and Mn ions

We report the luminescence properties and decay profiles of Ce：YAlO3, Mn：YAlO3, and Ce,Mn：YAlO3 crystals grown by Czochralski method. The spectroscopic properties show that both Mn2＋ ions and Mn4＋ ions exist in Mn：YA103 and Ce,Mn：YAlO3 crystals. The Mn2＋ ions have a broad emission band of 60 nm in Mn-doped YAlO3 crystal at 530 nm. The luminescence spectra also indicate that there is significant energy transfer between Ce3＋ and Mn4＋ in Ce,Mn：YA103 crystal. Because of the energy transfer, the first decay component in Ce,Mn：YAlO3 decreases from 24.5 to 10.8 ns, which is much faster than that of Ce：YAlO3.

Raman spectroscopy study of in situ change in laser irradiated LiMn_2O_4

A spinel LiMn2O4 is investigated via Raman spectroscopy at 514.5-nm excitation and X-ray diffraction. The dependence of Raman spectra on the different irradiated laser powers is determined and found to be different from that at 632.8-nm excitation. Based on our extensive analysis, our experimental results can be attributed to the laser heating effect, which reduces the Mn4＋ cation concentration in the local area. Consequently, the decrease in average Mn valence in the local area unavoidably induces the Jahn-Teller effect and local lattice distortion, which accounts for the evolution of the measured Raman spectra of spinel LiMn2O4.

Size influence on the fluorescence decay time of ZnS:Mn^(2+) nanocrystals

ZnS:Mn2+ nanocrystals(NCs) with particle size from 1.9 nm to 3.2 nm are synthesized via chemical precipitation method with different [S2-]/[Zn2+] ratios.The size-dependent decay for Mn emission exhibits a double exponential behavior.And two lifetime values,in millisecond time domain,can both be shortened with size increasing,which is attributed to enhanced interaction between host and Mn2+ impurity.A molecular structure model is proposed to interpret the tendency of two lifetime components,which is correlated to the number of S vacancy(Vs) defects around Mn2+.