Synthesis and structural,magnetic characterization of Zn(Mn)O diluted magnetic semiconductor

The bulk samples with nominal composition Zn_1−x Mn_x O [x = 5% and 7%] were synthesized at 930 °C by Standard Solid State Reaction method. The structural analysis reveals the single phase nature. The Topography study indicates the distribution of the particles. Magnetic property was affirmed by Vibrating Sample Magnetometer, Zn_1−x Mn_x O (with x = 5%), low concentration of dopant shows good ferromagnetism compared to high concentration in Zn_1−x Mn_x O (with x = 7%).     

Synthesis and characterization of arc deposited magnetic (Cr,Mn)2AlC MAX phase films

(Cr_1–xMn_x)₂AlC MAX phase thin films were synthesized by cathodic arc deposition. Scanning transmission electron microscopy including local energy dispersive X‐ray spectroscopy analysis of the as‐deposited films reveals a Mn incorporation of as much as 10 at% in the structure, corresponding to x = 0.2. Magnetic properties were characterized with vibrating sample magnetometry, revealing a magnetic response up to at least room temperature. We thus verify previous theoretical predictions of an antiferromagnetic or ferromagnetic ground state for Cr₂AlC upon alloying with Mn. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis, characterization, and kinetic study of Mn(DPM)3 used as precursor for MOCVD

Highly pure Mn(DPM)₃ (DPM-2,2,6,6-tetramethyl-3, 5-heptanedionato) complex, usually used as precursor for metal-organic chemical vapor deposition, was synthesized and characterized by elemental analyses, ¹H-NMR spectroscopy, mass spectroscopic analysis, thermogravimetry, and differential scanning calorimetry. The thermal decomposition behavior of the complex is sensitive to the ambient gases, and the oxygen atmosphere will accelerate the decomposition and oxidation of the complex. According to mass spectroscopic analysis at elevated temperature, one of the three DPM groups in Mn(DPM)₃ will dissociate primarily, following with dissociation of ⁺C(CH₃)₃ and ⁺OCCH₂COC(CH₃)₃ groups in sequence. It can be interpreted by the difference of metal ion radius. The kinetic parameters of activation energy and frequency factor were computed using different models and thereinto D2 model best adjusted the experimental isothermal thermogravimetric data.     

Synthesis and characterization of magnetic poly(glycidyl methacrylate) microspheres

Magnetic nanoparticles encapsulated in poly(glycidyl methacrylate) microspheres were prepared and their detailed structural and magnetic characteristics given. Iron oxide nanoparticles were obtained by chemical coprecipitation of Fe(II) and Fe(III) salts and stabilized with dextran, (carboxymethyl)dextran or tetramethylammonium hydroxide. The microspheres were prepared by emulsion or dispersion polymerization of glycidyl methacrylate in the presence of ferrofluid. The microspheres were uniform both in shape and usually also in size; their size distribution was narrow. All the magnetic parameters confirm superparamagnetic nature of the microspheres. Blocking temperature was not observed, suggesting the absence of magnetic interactions at low temperatures. This is most probably caused by complete encapsulation and the absence of agglomeration. Such microspheres can be used in biomedical applications.     

Synthesis and magnetic properties of three-dimensional metal (II) organophosphates

A new series of metal (II) organophosphates with the formula M(II) 2(H₂O)₂[O₃PCH₂(C₆H₄)CH₂PO₃] (M=Mn, Fe and Ni) have been prepared by hydrothermal synthesis. The structure consisted of two-dimensional metal–oxygen inorganic layers is pillared by p-xylylenediphosphonate to form a three dimensional framework. The layers are constructed by corner-sharing metal oxygen polyhedron. A study on the magnetism of the materials indicates the presence of spin canted antiferromagnetc interactions. The manganese and iron compounds represent the interesting 3D metal organophosphate molecular metamagnet due to spin canted antiferromagnetic with high critical temperature (40 K for Mn; 16 K for Fe). The infinite M–O–M layers are believed to be responsible for this high performance.     

Domain walls in the (Ga,Mn)as diluted magnetic semiconductor

We report experimental and theoretical studies of magnetic domain walls in an in-plane magnetized (Ga,Mn)As dilute moment ferromagnetic semiconductor. Our high-resolution electron holography technique provides direct images of domain wall magnetization profiles. The experiments are interpreted based on microscopic calculations of the micromagnetic parameters and Landau-Lifshitz-Gilbert simulations. We find that the competition of uniaxial and biaxial magnetocrystalline anisotropies in the film is directly reflected in orientation dependent wall widths, ranging from approximately 40 to 120 nm. The domain walls are of the Néel type and evolve from near-90 degrees walls at low temperatures to large angle [11[over ]0]-oriented walls and small angle [110]-oriented walls at higher temperatures.     

叶绿素a锰（Ⅲ）和叶绿素a锰（Ⅱ）的合成和光谱

叶绿素ａ锰（Ⅲ）（Ｍｎ（Ⅲ）－Ｃｈｌ－ａ）由脱镁叶绿素（Ｐｈｅｏ－ａ）和醋酸锰（Ⅱ）合成而得，用反相高效液相色谱法分离纯化，叶绿素ａ锰（Ⅱ）（Ｍｎ（Ⅱ）－Ｃｈｌ－ａ）用Ｎａ２Ｓ２Ｏ４还原时绿素ａ锰（Ⅲ）获得，研究了它们的元素分析（ＥＡ），紫外可见吸附光谱（ＵＶ－Ｖｉｓ）和傅里叶红外吸收光谱（ＦＴ－ＩＲ）证明了此二种配合物的合成，并给出了（Ｍｎ（Ⅲ）－Ｃｈｌ－ａ）与（Ｍｎ（Ⅱ）－Ｃｈｌ－ａ）的组成分     

Carrier-induced magnetic ordering control in a digital (Ga,Mn)as structure

With the full potential linearized augmented plane method, we theoretically investigated the carrier-induced magnetization reversal in digital (Ga,Mn)As heterostructures with varying distance between the two Mn layers along with the distribution and concentration of external carriers. The presence of external holes induces switching from the antiferromagnetic to ferromagnetic state when d(Mn-Mn)=16.96 A, whereas the addition of electrons produces no significant effect. We demonstrate a possibility to separately control T(c) and magnetic reversal in digital (Ga,MN)As alloys.     

Synthesis, Characterization and Reactivity Study of a New Penta-Coordinated Mn(II) Complex

A penta-coordinated Mn(II) compound [dqpMnCl₂] (1) (dqp = 2,6-di-(8-quinoline-yl)-pyridine) has been synthesized and its X-ray crystallographic structure is reported here. Magnetic susceptibility measurements confirmed a high-spin Mn(II) (S = 5/2) center in 1. The X-band EPR spectrum of 1 in dimethylformamide solution exhibits widely distributed transitions in the spectral range from 0 to 700 mT with particularly well-resolved hyperfine lines due to the ⁵⁵Mn (I = 5/2) nucleus. The abundance of highly resolved transition lines in the spectrum facilitated the electron paramagnetic resonance spectral simulation which revealed large zero-field splitting and g-anisotropies. When dissolved, 1 exists in equilibrium with a hexa-coordinated species, the latter probably resulting from disassociation of one chlorido-ligand allowing ligation of two solvent molecules. The redox behavior of 1 was studied and was compared to that of a structural analog for which water oxidation in the presence of a chemical oxidant has been shown. The results from water oxidation trials of 1 are discussed.     

Site symmetry of Mn(II) and Co(II) in zinc phosphate glass

Optical absorption and EPR spectra of Mn(II) and Co(II) doped zinc phosphate glasses have been investigated. Crystal filed parameters and g values are determined. For Mn(II) doped glass the values are Dq=850, B=850, and g values are around 2 at room temperature (RT). For Co(II) doped glass, Dq=890, B=700, and g=4.45 and 2.06 at liquid nitrogen temperature. The optical and EPR data has been correlated.     

Control of magnetic anisotropy in (Ga,Mn)as by lithography-induced strain relaxation

We report control of magnetic anisotropy in epitaxial (Ga,Mn)As by anisotropic strain relaxation in patterned structures. The strain in the structures is characterized using reciprocal space mapping by x-ray techniques. The magnetic anisotropy before patterning of the layer, which shows biaxial easy axes along [100] and [010], is replaced by a hard axis in the direction of large elastic strain relaxation and a uniaxial easy axis in the direction where pseudomorphic conditions are retained.     

Ni（Ⅱ）,Cu（Ⅱ）,Zn（Ⅱ）的硝酸盐与氟哌酸的固态配合物的 …

由氟哌酸与Ｎｉ（Ⅱ）、Ｃｕ（Ⅱ）、Ｚｎ（Ⅱ）的硝酸盐合成了三个未见报道的固态配合物,并用元素分析、摩尔电导、红外光谱、热重分析表征了它们的组成和性质。     

Polarization of valence band holes in the (Ga,Mn)as diluted magnetic semiconductor

We report on direct measurements of the impurity band hole polarization in the diluted magnetic semiconductor (Ga,Mn)As. The polarization of impurity band holes in a magnetic field is strongly enhanced by antiferromagnetic exchange interaction with Mn ions. The temperature dependence of the hole polarization shows a strong increase of this polarization below the Curie temperature. We show that the ground state of the impurity band is formed by uniaxial stress split F=+/-1 states of antiferromagnetically coupled Mn ions (S=5/2) and valence band holes (J=3/2). The gap between the Mn acceptor related impurity band and the valence band is directly measured in a wide range of Mn content.     

Synthesis and magnetic properties of Mn doped CuO nanowires

Study of diluted magnetic semiconductor nanowires is one of the important topics in materials science. By using Mn-Cu alloy as the starting material, Mn doped CuO nanowire arrays have been synthesized in air at the temperature of 550 °C. X-ray diffraction measurements and scanning electron microscopic study shows that the nanowires were grown on Cu₂O substrate. Transmission electron microscopic study shows the single crystal property of the nanowires. Magnetic measurements show ferromagnetic property in the Mn doped CuO nanowires with the critical temperature higher than 80 K.     

Synthesis and magnetic properties of Mn doped ZnO nanowires

Mn doped ZnO nanowires have been synthesized using a simple autocombustion method. The as-synthesized Mn doped ZnO nanowires were characterized by X-ray diffraction and transmission electron microscopy. An increase in the hexagonal lattice parameters of ZnO is observed on increasing the Mn concentration. Optical absorption studies show an increment in the band gap with increasing Mn content, and also give evidence for the presence of Mn²⁺ ions in tetrahedral sites. All Zn_1−xMn_xO (0≤x≤0.25) samples are paramagnetic at room temperature. However, a large increase in the magnetization is observed below 50 K. This behavior, along with the negative value of the Weiss constant obtained from the linear fit to the susceptibility data below room temperature, indicate ferrimagnetic behavior. The origin of ferrimagnetism is likely to be either the intrinsic characteristics of the Mn doped samples, or due to some spinel-type impurity phases present in the samples that could not be detected.     

Luminescence spectra of Mn(II) in different symmetries

Luminescence emission and excitation spectra of high-spin Mn(II) were studied in crystals with different site symmetries of the divalent ion. For cubic or uniaxial site symmtries only one emission band is observed with a maximum asymmetry of 20% and larger width on the low energy side. Lower site symmetries may result in spectra of considerable complexity. A second emission band of lower intensity near 14 000 cm^-1 was found in systems with hexa- as well as tetra-coordinated Mn(II). It evidently originates from the same Mn(II) that gives rise to the stronger emissions at higher energies. A qualitative explanation for its occurence on the basis of close-lying split components of the ⁴T₁(G) or ⁴T₂(G) states is presented. In two systems emission bands from higher excited states and shifts of emission maxima with excitation energy were observed. The shifts are explained on the basis of overlapping bands and variable intensity ratios for these unresolved components. The results indicate that the degree of distortion is more important for the occurrence of these complications than the actual site symmetry of Mn(II).     

Synthesis and characterization of a POM-based nanocomposite as a novel magnetic photocatalyst

A novel magnetic photocatalyst, prepared by grafting polyoxometalates (POM) anions PW₁₂O₄₀³⁻ onto Fe₃O₄ nanoparticles via a layer of Ag, was synthesized and characterized. The coated Ag layer was used as an intermediate bond for anchoring POM anions onto the magnetite cores. Resulting materials have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherm, magnetization, and inductively coupled plasma (ICP). The activity of the photocatalyst was tested by the photocatalytic degradation of Rhodamine B. It was found that, compared to pure POM, the decolorization fraction of Rhodamine B in 2 h operation was 2.8-3.4 times higher by using the POM-based nanocomposite. ICP analysis of the concentration of Fe, W and P in treated water showed that photodissolution was minimal. In addition, as the synthesized composite possesses a magnetite core, it is possible to retrieve the photocatalyst by exerting an external magnetic field, which is easier than the recovery of conventional TiO₂ fine particles and homogeneous POM photocatalysts. The exhibited photocatalytic activity and magnetization of the novel photocatalyst provide a promising solution for the degradation of water contaminants and photocatalyst recovery.     

Synthesis, characterization and analytical applications of Ni(II)-ion imprinted polymer

Ion recognition-based separation techniques have received much attention because of their high selectivity for target ions. In this study, we have prepared a novel ion imprinted polymer (IIP) to remove nickel ions with high selectivity. The imprinted polymer was prepared by copolymerization of 2-hydroxy ethyl methacrylate (HEMA) with nickel vinylbenzoate complex in the presence of ethylene glycol dimethacrylate (EGDMA) as a crosslinker. The polymerization was carried out in bulk with free radical initiation using 2-methoxy ethanol as a solvent and porogen. The adsorbed nickel was completely eluted with 15 mL of 1 M HCl. Control polymer was also prepared by similar experimental conditions without using imprint ion. The above synthesized polymers were characterized by surface area measurements, FT-IR, microanalysis and SEM analysis. The adsorption capacity of IIP and CP was found to be 1.51 and 0.65 mmol g⁻¹, respectively. The optimal pH for quantitative enrichment was 6.5. Nature of eluent, eluent concentration and eluent volume were also studied. The relative selectivity factor (α_r) values of Ni(II)/Zn(II), Ni(II)/Cu(II) and Ni(II)/Co(II) were 78.6, 111.1 and 91.6, respectively. Five replicate determinations of 30 μg L⁻¹ of Ni(II) gave a mean absorbance of 0.067 with a relative standard deviation of 1.06%. The lowest concentration determined by GTA-AAS below which the recovery becomes non-quantitative is 6 μg L⁻¹. IIP was tested for removal of Ni(II) from sea water sample.     

Mn掺杂SiC磁性薄膜的结构表征

利用反射式高能电子衍射(RHEED)、X射线衍射(XRD)和X射线吸收近边结构谱(XANES)等技术研究了在950 ℃条件下Si(111)衬底上共蒸发分子束外延方法制备的Mn掺杂SiC磁性薄膜的结构特征.RHEED结果表明,生长的Mn掺杂SiC薄膜为立方结构.XRD和XANES结果表明,在Mn掺杂量为0.5％和18%的样品中,Mn原子均是与SiC半导体介质中的Si原子反应生成镶嵌在SiC基体中的Mn₄Si₇化合物颗粒,并未观察到在SiC晶格中有替代式或间隙式的M