Mn Cd Research Articles

Microstructure Evolution and Mechanical Properties of TiB2/Al–Cu–Mn–Cd Composite with the Adoption of Two-Stage Solution and Aging Treatment

Microstructure Evolution and Mechanical Properties of TiB2/Al–Cu–Mn–Cd Composite with the Adoption of Two-Stage Solution and Aging Treatment

Modification strategies and applications of Mn–Cd–S solid solution-based photocatalysts

Semiconductor photocatalyzed energy production and environment treatment have received a lot of attention. Mn–Cd–S solid solutions (MnxCd1−xS) with tunable band structure, suitable redox capacity, and visible light response is recognized as one of the most promising photocatalysts for practical applications. However, low separation efficiency of photogenerated carriers and sluggish reaction kinetics restricts its photocatalytic activity. This review discusses the advantages and drawbacks of MnxCd1−xS for photocatalysis in terms of electronic band structure and surveys the modification strategies of photocatalytic activity, including modulation of Mn/Cd ratio, morphology/structure regulation, defect engineering, construction of heterojunction, loading cocatalysts, and integration of multiple strategies. Then, the progress in photocatalytic water splitting to hydrogen, carbon dioxide reduction, and pollutant degradation using MnxCd1−xS-based materials are summarized. Finally, it is concluded by outlining the challenges and opportunities for developing efficient photocatalysts based on MnxCd1−xS.

Microstructure evolution and mechanical properties of Al–Cu–Mn–Cd alloy fabricated by CMT-wire arc additive manufacturing

The high-performance additive manufacturing of relatively small aluminum alloy components has been widely proven successful. However, wire arc additive manufacturing (WAAM) has always been challenging in achieving uniform microstructure and high mechanical properties when manufacturing large-sized parts. Therefore, this study used cold metal transition wire arc additive manufacturing (CMT-WAAM) to prepare Al-5.49Cu-0.4Mn-0.29Cd (ACMC) alloy to obtain a uniform microstructure and improve its mechanical properties. The results show that the as-deposited (AD) samples have an obvious layered deposited structure. The grains in the microstructure are all equiaxed crystals and a large amount of copper-rich eutectic phase precipitates at the grain boundaries. After heat treatment, the vast majority of the eutectic phase dissolves, and θ'phase, with a size of 100–200 nm, uniformly precipitates in the α-Al matrix. The ultimate tensile strength (UTS) and yield strength (YS) of the heat-treated (HT) specimen can reach 483.7 MPa and 412.3 MPa, respectively. There is no significant difference in the mechanical properties between the transverse and longitudinal directions of thin-walled samples. Based on experimental results and theoretical analysis, the strengthening mechanism and fracture mechanism of CMT-WAAM aluminum alloy were revealed. This work provides a theoretical basis for the microstructure optimization and mechanical performance improvement of ACMC alloy, which is of great significance for the high-performance preparation of large-sized components in the aerospace field.

O-MoS2/Mn0.5Cd0.5S composites with enhanced activity for visible-light-driven photocatalytic hydrogen evolution

The reaction mechanism of O-MoS2/Mn0.5Cd0.5S for photocatalytic hydrogen evolution is put forward and the satisfactory hydrogen production rate of the optimized composite is superior to most of the Mn–Cd–S based catalysts reported.

The effectiveness of various treatments in changing the nutrient status and bioavailability of risk elements in multi-element contaminated soil.

Potential changes in the mobility and bioavailability of risk and essential macro- and micro-elements achieved by adding various ameliorative materials were evaluated in a model pot experiment. Spring wheat (Triticum aestivum L.) was cultivated under controlled condition for 60days in two soils, uncontaminated Chernozem and multi-element contaminated Fluvisol containing 4900 ± 200mg/kg Zn, 35.4 ± 3.6mg/kg Cd, and 3035 ± 26mg/kg Pb. The treatments were all contained the same amount of sulfur and were as follows: (i) digestate from the anaerobic fermentation of biowaste, (ii) fly ash from wood chip combustion, and (iii) ammonium sulfate. Macro- and micro-nutrients Ca, Mg, K, Fe, Mn, Cu, P, and S, and risk elements Cd, Cr, Pb, and Zn were assayed in soil extracts with 0.11mol/l solution of CH3COOH and in roots, shoots, and grain of wheat after 30 and 60days of cultivation. Both digestate and fly ash increased levels of macro- and micro-nutrients as well as risk elements (especially Cd and Zn; the mobility of Pb decreased after 30days of cultivation). The changes in element mobility in ammonium sulfate-treated soils appear to be due to both changes in soil pH level and inter-element interactions. Ammonium sulfate tended to be the most effective measure for increasing nutrient uptake by plants in Chernozem but with opposite pattern in Fluvisol. Changes in plant yield and element uptake in treated plants may have been associated with the higher proline content of wheat shoots cultivated in both soils compared to control. None of the treatments decreased uptake of risk elements by wheat plants in the extremely contaminated Fluvisol, and their accumulation in wheat grains significantly exceeded maximum permissible levels; these treatments cannot be used to enable cereal and other crop production in such soils. However, the combination of increased plant growth alongside unchanged element content in plant biomass in pots treated with digestate and fly ash suggests that these treatments have a beneficial impact on yield and may be effective treatments in crops grown for phytoremediation.

Effects of vanadium and cadmium on transformation temperatures of Cu–Al–Mn shape memory alloy

Cu-based quaternary shape memory alloys were extensively investigated alloy in last decade. In this study, Cu–Al–Mn, Cu–Al–Mn–V and Cu–Al–Mn–Cd shape memory alloys were produced by arc melting. We have investigated the effects of the alloying elements on the characteristic transformation temperatures, variations in structure and microstructure. The characterization of the transformation temperatures was studied by the differential scanning calorimetry. It was observed that the addition of the vanadium and cadmium decreases the characteristic transformation temperatures. The structural changes of the samples were studied by X-ray diffraction measurements and optical microscope observations. The crystal structure of the martensite Cu–Al–Mn, Cu–Al–Mn–V and Cu–Al–Mn–Cd shape memory alloys were identified as M18 at room temperature. The crystallite sizes of the alloys were determined. The microstructure of the alloy was studied with the help of optical microscope and V-type martensites with different orientations were detected. Microhardness value of the alloys were found between 194 and 211 Hv.

Application of multivariate geostatistics in the investigation of heavy metal contamination of roadside dusts from selected highways of the Greater Toronto Area, Canada

A good understanding of roadside soil contamination and the location of pollution sources is important for addressing many environmental problems. The results are reported here of an analysis of the content of metals in roadside dust samples of four major highways in the Greater Toronto area (GTA) in Ontario, Canada. The metals analyzed are Pb, Zn, Cd, Ni, Cr, Cu, Mn, and Fe. Multivariate geostatistical analysis [correlation analysis (CA), principal component analysis (PCA), and hierarchical cluster analysis (HCA)] were used to estimate soil chemical content variability. The correlation coefficient shows a positive correlation between Cr–Cd, Mn–Fe, and Fe–Cu, while negatively between Zn–Cd, Mn–Cd, Zn-Cr, Pb–Zn, and Ni–Zn. PCA shows that the three eigenvalues are less than one, and suggests that the contamination sources are processing industries and traffic. HCA classifies heavy metals in two major groups. The cluster has two larger subgroups: the first contains only the variables Fe, Mn, Cu, Cr, Ni, and Pb, and the second includes Cd and Zn. The geostatistical analysis allows geological and anthropogenic causes of variations in the contents of roadside dust heavy metals to be separated and common pollution sources to be identified. The study shows that the high concentration of traffic flows, the parent material mineralogical and chemical composition, and land use are the main sources for the heavy metal concentration in the analyzed samples.

亚热带樟树-马尾松混交林凋落物量及养分动态特征

This study selected typical needle and broadleaved subtropical forests( camphor and pinus massoniana mixed forests) as the research object; from 2009 to 2011 the litter fall was investigated monthly. The results showed that the annual litterfall production was( 4634. 723±337. 1427) kg / hm2,and foliage accounted for 71.78% branches( 26. 24%) litter debris( 8. 46%) fruits( 3. 23%). The total amount of litterfall had the obvious monthly dynamic. In November,its maximum was 1025. 6 kg / hm2; the minimum appears in February which was 138. 606 kg/hm2. There were significant differences of macroelemens and microelements in mixed forest. The order of the macroelemens was CNCaKSMgP, as the microelement was MnFeZnPbCdCuNiCo. The features of C / N was: the branch( 66. 96%) fruit( 63. 48%) leaf( 40. 62%). The content of litter nutrient directly determines the amount of nutrients return in forest. The amount of litter nutrients return was 80. 936 kg / hm2in Camphor and pinus massoniana mixed forest. The features of litter nutrients return of each element size sequence was: N Ca K S Mg P Mn Fe Zn Pb Cd Cu Ni Co. The characteristics of various components of the nutrients return was: leaf( 67. 469 kg / hm2) branch( 14.928kg/hm2) fruit( 2.361 kg/hm2). The amount of N return in mixed forest was 40. 964 kg/hm2. Among this,the return amount of N in leaf had a value of 34. 877 kg / hm2.

Ag-doped Mn–Cd sulfide as a visible-light-driven photocatalyst for H2 evolution

We have investigated the role of Ag in the AgyMn1−x−yCdxS during photocatalytic H2 evolution under visible light irradiation (λ>420nm). The rate of H2 evolution increased with the amount of Ag doping, and reached a maximum at y=0.003 (x=0.40). AgyMn1−x−yCdxS consisted of a highly crystalline solid solution phase over the range 0.48≤x≤0.63 and 0≤y≤0.02, suggesting that the effect of Ag on the photocatalytic activity is not associated with crystallinity. UV–vis absorption spectra of AgyMn1−x−yCdxS showed a band gap absorption at 500nm and a flat absorption above 500nm. The latter absorption was caused by the presence of Ag2S, which does not significantly contribute to the photocatalytic activity. X-ray photoelectron spectroscopy detected metallic Ag on the surface of Ag0.003Mn0.40Cd0.60S, which could act as a co-catalyst in photocatalytic hydrogen evolution.

Quantitative speciation of heavy metals in soil and crops of agricultural fields of Islamabad, Pakistan

Two root crops: carrot (Daucus carota) and spring onion (Allium fistulosum) and soil samples were selected from the agricultural fields located near Islamabad, Pakistan to determine their elemental content. Field soil speciation of the two crops was also carried out to analyse the correlation of the elements in field crop and soil. Concentrations of selected elements were evaluated in the leaf, stem, root and flowering part of the crops using flame atomic absorption spectrophotometry. The results showed that elements are mostly concentrated in soil rather than crop parts following the sequence Zn>Cu>Pb>Ni>Cr>Cd. Furthermore, soil speciation showed that Ni and Cr are more prevalent in the Fe–Mn oxide fraction, Zn and Cd as the carbonate bound fraction and Cu is found in the organic bound form. However, concentrations of Pb are similar across the carbonate, Fe–Mn oxide and organic bound fractions. The highest average concentration of Zn is found as the carbonate bound fraction (2.09 ± 0.005 mg kg−1) and Cu as the organic bound (1.51 ± 0.029 mg kg−1) in soil samples taken from the agricultural field of Daucus carota.

Hydrothermal Synthesis of a Doped Mn‐Cd‐S Solid Solution as a Visible‐Light‐Driven Photocatalyst for H2 Evolution

The effect of metal doping (i.e., with Cr, Fe, Ni, Cu, Zn, Ag and Sn) on the crystal structure of hydrothermally synthesized Mn(1-x)Cd(x) S (where x≈0.1) is studied with the aim of enhancing photocatalytic activity. In contrast to the low-crystalline, undoped solid solution Mn(1-x)Cd(x)S, Ni doping yields a well-crystallized wurtzite-type Mn-Cd-S solid solution, which precipitates as planar hexagonal facets of several hundred nanometers in size, together with much larger grains of α-MnS (>10 μm). By removing inactive α-MnS through sedimentation, a single phase with composition of Ni(0.01)Mn(0.56)Cd(0.43)S is obtained successfully. The Ni doping achieved a threefold higher photocatalytic activity for H(2) evolution from a 0.1 M Na(2)S/0.5 M Na(2)SO(3) solution under visible-light irradiation (λ≥420 nm). The apparent quantum yield of 1 wt % Pt-loaded Ni(0.01)Mn(0.56)Cd(0.43)S measured at λ=420 nm reached 25 %. The enhanced photocatalytic activity is most likely the result of a decreased concentration of defects, responsible for electron-hole recombination, in the active solid-solution phase and a slightly higher bandgap energy (2.4 eV).

Bistrimethylsilylamide Transition-Metal Complexes as Starting Reagents in the Synthesis of Ternary Cd−Mn−Se Cluster Complexes

The use of bis-trimethylsilylamide transition-metal complexes soluble in organic solvents offers new perspectives for the synthesis of metal chalcogenide cluster molecules, especially for multicomponent clusters. This is illustrated by the synthesis of the mixed cadmium-manganese chalcogenide clusters [Cd(4)Mn(6)Se(4)(SePh)(12)(P(n)Pr(3))(4)] and [Cd(4)Mn(4)S(SePh)(14)(P(n)Pr(3))(2)] as reported here. These cluster molecules display interesting properties, such as a photoluminescence in the red to near-infrared spectral region, which is particularly bright at temperatures below approximately 100 K, and an antiferromagnetic coupling between the manganese(II) ions. Electrospray Fourier transform ion cyclotron resonance mass spectra from the chemically charged clusters in solution show several ionic cluster species which indicate a fast Cd/Mn exchange in solution. Furthermore, single crystal X-ray analysis and magnetic measurements supported by density functional theory calculations suggest a cocrystallization of structural isomers of the ideal cluster composition [Cd(4)Mn(4)S(SePh)(14)(P(n)Pr(3))(2)] as well as of species with the general formula [Cd(4+x)Mn(4-x)S(SePh)(14)(P(n)Pr(3))(2)] (x < 0 Mn enrichment; x > 0 Cd enrichment) without a significant decrease in the stability. Thermal cleavage of [Cd(4)Mn(6)Se(4)(SePh)(12)(P(n)Pr(3))(4)] results, in agreement with the CdSe/MnSe phase diagram, in the formation of a mixture of a hexagonal phase Cd(1-x)Mn(x)Se (x approximately 0.5) and a cubic phase Mn(1-x)Cd(x)Se (x < 0.05).

RBS spectrometric studies on the interdiffusion profile of multilayer thin film structure to yield Cd 1− xMn xTe alloy

Thin films of Cd 1− x Mn x Te, a potentially important spintronic material, were fabricated using thermal interdiffusion of MnTe–CdTe bilayers and Mn–Cd–Te trilayers. The impact of the number of repeat layers on the interdiffusion profile was investigated using RBS spectrometry. A working number of layer repetitions were found out for the multilayer structure to produce Cd 1− x Mn x Te. Hall measurements of the multilayers supported the conclusions drawn from the RBS data. Magneto-optic Kerr effect studies were also carried out with the optimized multilayers. Apart from single crystal growth, this methodology of fabrication of Cd 1− x Mn x Te may serve as a simple process of fabrication of DMS alloy films.

Metal Contamination in Nullah Dek Water and Accumulation in Rice

A research study was carried out to determine the electrical conductivity (EC), residual sodium carbonate (RSC), sodium adsorption ratio (SAR), p H and metals in metal-polluted irrigation water from a nullah and those in soils over a period of time, and the effect of metals on rice yield and metal concentrations in rice grain and straw. Two sites (I and II) were selected on the bank of Nullah Dek at Thatta Wasiran in Sheikhupura District (Pakistan), with two rice varieties. Super Basmati and Basmati 385, at both sites. Water samples were collected during rice crop growth at 15-day intervals from August 3 to November 1, 2002. The results showed that Nullah Dek water had an EC >1.0 dS m −1 and RSC of 2.78–4.11 mmol c L −1, which was hazardous for crops, but the SAR was within the safe limit. Cu, Mn Cd and Sr were also within safe limits. The soil analysis showed that Site II was free from salinity/sodicity, whereas Site I was saline sodic. Among metals, Zn was sometimes deficient, Cu, Mn and Fe were adequate, and Sr, Ni and Cd were within safe limits in the soil at both the sites. After the rice crop harvest, concentrations of all metals tested were usually slightly increased, being higher in the upper soil layer than the lower. In addition, Basmati 385 produced higher rice grain and straw yield than Super Basmati. Chemical analysis of rice grain indicated the presence of Zn, Cu, Fe, Mn, Pb and Sr, whereas rice straw contained Zn, Cu, Fe, Mn and Sr, with Cd and Ni both being found in minute quantities.

Electronic properties of the Mn–CdTe(1 1 0) interface probed by resonant photoemission at the Mn 2p–3d absorption threshold

Resonant photoemission at the Mn 2p → 3d absorption threshold is used to probe the distribution of the Mn spectral weight in the valence band of Mn thin layers grown onto the CdTe (1 1 0) surface. It is shown that at the early stages of the evaporation process, a Cd–Mn–Te surface alloy is formed, even at room temperature. The Mn 3d spectral weight in the valence band, which is enhanced across the resonance, is quite similar to that observed for Cd 1− x Mn x Te single crystals. At larger Mn coverages, the growth of a metallic Mn phase on top of the Mn–Cd–Te surface alloy is detected both at resonance and by collecting Mn 2p core level photoemission data.

Tight Binding Approach to the Electronic Properties of MnTe/CdTe Structures

Ultrathin MnTe and CdTe films as well as MnTe/CdTc/MnTe sandwich structures are investigated. Band structure, local densities of states corresponding to Mn(Cd) and Te ions are calculated. Local magnetic moments are also found. Strong modifications of the density of states in the boundary MnTe and CdTe layers are obtained. A small negative splitting of the valence band edge is found at the interface, though no splitting is obtained in the MnTe barrier. The result is consistent with magnetooptical measurements performed for MnCdTe/CdTc heterostructures giving the enhanced Zeeman splitting at the interfaces.

Manganese diffusion in MBE-grown Cd(Mn)Te structures

The diffusion of Mn into CdTe films grown by molecular beam epitaxy (MBE) on (100)GaAs substrates was studied by secondary ion mass spectrometry (SIMS). The samples were: 2 monolayer thick δ-MnTe embedded in either semi-insulating or in indium-doped CdTe (NIn = 1 × 1018cm−3, and a 300 nm thick Cd0.75Mn0.25Te layer buried in undoped CdTe. Thermal annealing was performed in H2 atmosphere at temperatures of 333–530°C with samples covered face-to-face to avoid vaporization. In the δ-MnTe samples the annealing caused symmetric spreading of the Mn marker in accordance with Fick's law. The activation energy for diffusion of Mn in CdTe evaluated from the corresponding Arrhenius plot is Ed = 1.35 eV irrespective of doping. The absolute value of the Mn diffusivity in the In-doped CdTe is larger by a factor of 200 than that in the undoped layer. In layered CdTe/CdMnTe/CdTe structures the MnCd interdiffusion is associated with a higher activation energy than the diffusion of the diluted Mn solute. The intermixing is strongly asymmetric, being much more pronounced at the interface closer to the surface of the film.

Synthesis, spectroscopic studies and crystal structure of cadmium nitrosylpentacyanomanganate (I) pentadecahydrate

The structural analysis of Cd 3[Mn(CN) 5NO] 2·15H 2O using single-crystal diffractometry and full-matrix least-squares refinement has yielded residuals of 0.027 ( R) and 0.034 ( R w) based on 2659 observed reflections. The nitrosyl complex crystallizes in the centrosymmetric triclinic space group P 1 with cell parameters a=7.8349(9), b=9.6412(7), c=12.7208(7) Å, α=99.022(5), β=106.591(6), γ=102.152(7)°, V=875.8(1) Å 3 and Z=1. The observed density is 1.99(1) g cm −3 ( D c=1.97(1) g cm −3). A thermogravimetric study reveals 14–15 water molecules per formula unit. Both Cd and Mn atoms have slightly distorted octahedral geometries and are linked by cyanide bridging. Within any given chain of CdMnCdmnCd, the end cationic Cd atoms are fac-coordinated by three cyanide groups and three water molecules. Whereas, the central Cd atom is ligated to four cyanide groups and two trans-oriented water molecules. The Mn atoms are bonded to five cyanide bridging groups and one nitrosyl group. Notable bond lenghts are: Cd N(mean) =2.28(4), Cd(mean)O=2.37(4), MnC(mean) 1.99(2), MnNO=1.645(4), NO=1.174(7) and C=N(mean)=1.144(7) Å. Infrared spectroscopic data are presented.

Synthetic, analytical and kinetic studies on a crystalline and thermally stable phase of antimony(V) arsenosilicate cation exchanger

A new, thermally stable and crystalline phase of antimony(V) arsenosilicate has been synthesized and characterized using X-ray, IR, TGA and DTA studies in addition to ion exchange studies such as determination of ion exchange capacity, elution, pH titration and distribution behaviour. On the basis of the distribution behaviour the material has been found to be highly selective for iron. Some binary separations of metal ions such as Sr(II)Cd(II) and Mn(II)Cd(II) have also been performed on a column of this material. The X-ray studies reveal the crystalline nature of the material, indicating a cubic structure. The kinetics of exchange for the metal ions has also been studied and some physical parameters such as the self-diffusion coefficient D 0, energy E a and entropy ΔS* of activation have been determined.

Effects of interfacial strength on fatigue crack growth in a fiber-reinforced titanium-alloy composite: Chan, K.S. and Davidson, D.L. Metall. Trans. A June 1990 21A, (6), 1603–1612

In recent years, there has been a renewed interest in understanding the mechanical properties and microstructural characteristics of aluminum alloys containing lithium, because of their potential for extensive use in aerospace applications. In the present paper the fatigue crack propagation behavior of aluminum alloy 2020 (AlCuLiMnCd) in the peak strength temper is examined over a wide range of growth rates (from 10−6 to 10−11 m cycle−1). It was found that alloy 2020 shows crack propagation rates that are up to an order of magnitude slower at intermediate ΔK levels and up to two orders of magnitude slower in the near-threshold region, when compared with aluminum alloy 7075 under conditions of similar yield strength, load ratio, frequency and environment. Extensive analyses of the crack path for alloy 2020 reveal that pronounced deflection and branching of the fatigue crack occur at all growth rate levels as a result of a highly crystallographic mode of crack advance. The micromechanisms of fatigue crack growth in alloy 2020 are examined in terms of crack profile, fracture surface features, microstructure and environment.