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941.
Half-metallic ferromagnetism in the Ga1 ? xCr x N compound at different concentrations, x = 25, 12.5 and 6.25 %, have been investigated using density functional theory as implemented in code Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA) using LDA + U as exchange-correlation (XC) potential, to find out the possibility of new diluted DMSs. The outcomes reveal that transition metal atom (Cr) doping in GaN induces ferromagnetism. The 3d levels of the TM ion originate a half-metallic gap at the Fermi level in the majority spin channel for all concentrations. Moreover, diluted magnetic semiconductor compounds retain the half-metallic nature at all concentrations, i.e., x = 0.25, 0.125 and 0.0625, with 100 % spin polarization at the Fermi level (E F). The total magnetic moment of these compounds is due to Cr-3d states, and the existence of a small magnetic moment on Ga and N, non-magnetic atoms, for all doping concentrations is a consequence of p-d hybridization of Cr-d and N-p states. The calculated values of s-d exchange constant N α and p-d exchange constant N βconfirm the ferromagnetic character of the Cr-doped GaN compound. 相似文献
942.
Ren Zhang Yunhua Zhou Yiyi Zhu Yangyang Li Liang Chu Yonggang Min Jian Zhang Jianping Yang Xing’ao Li 《Journal of Superconductivity and Novel Magnetism》2017,30(9):2471-2479
Tetragonal BiFeO3 (BFO), which has a giant spontaneous polarization, has attracted a great deal of attention recently. In this paper, we systematically study the structural, magnetic, electronic and optic properties of BFO, BiFe0.75Mn0.25 O 3 (BFMM), and BiFe0.75Ti0.125Mn0.125 O 3 (BFMT). Results show that doping Ti and Mn into the Fe sites increases the c/a ratio and enhances the magnetization of BiFeO3 from 0 to 5 μB. The crystal symmetry changes from orthogonality to tetragonality with half of the Mn atoms being replaced by Ti in BiFe0.75Mn0.25 O 3, which suppresses the energy splitting of the Mn 3d orbitals and thus enlarge the band gap to 1.21 eV for BiFe0.75Ti0.125Mn0.125 O 3. Our calculated Bader charge and charge density difference show that the smallest volume of BiFe0.75Mn0.25 O 3 arises from the strong Mn–O bonds in BiFe0.75Mn0.25 O 3. Further investigations indicate similar optical behaviors for BiFeO3 and BiFe0.75Ti0.125Mn0.125 O 3. However, BiFe0.75Mn0.25 O 3 exhibits strong absorption in the infrared region for the transition from O 2p to Mn \({e_{g}^{2}}\) and \(t_{2g}^{3}\). 相似文献
943.
Sanjay Sahare Ravi Kant Choubey Gurunath Jadhav Tejashree M. Bhave Samrat Mukherjee Sunil Kumar 《Journal of Superconductivity and Novel Magnetism》2017,30(6):1439-1446
In this report, we studied various structural and optical properties of pure and copper-doped cadmium oxide (CdO) thin films. Nanostructured Cu-doped CdO films were deposited using sol–gel spin-coating technique. The structural and morphological changes have been observed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM) studies. The optical and electrical properties of the pure and Cu-doped CdO thin films were studied by UV–vis spectroscopy and four-point probe method, respectively. The XRD peaks show the formation of nanocrystalline CdO with cubic face-centered crystal structure. The band gaps of the as deposited films were found in the range of 2.32–2.73 eV, while after doping, it decreases due to structural deformation. The electrical resitivity was found to decrease approximately ~10 in Cu-doped CdO thin films. 相似文献
944.
Yan-kun Tang Qian Yang Xiao-fei Si Jin-kang Han Wei-wei Cao Ya-fei Li Fang Liu Xiaoyan Yao Ya Zhai 《Journal of Superconductivity and Novel Magnetism》2017,30(6):1527-1531
In this study, we report the results of an investigation into the sintering temperature dependence of magnetic and transport properties for GdBaCo2 O 5 + δ synthesized through a sol-gel method. The lowering of sintering temperature leads to the increase of oxygen content and the reduction of grain size. The increase of oxygen content results in the enhancement of magnetic interactions and the weakening of Coulomb repulsion effect, while the reduction of grain size improves the magnetoresistance effect. Metal-insulator transition accompanied with spin-state transition is observed in all samples. 相似文献
945.
The superconducting properties of Nb2PdS5 superconductor have been investigated with Ni doping at Pd site All the bulk polycrystalline Nb2Pd1?xNix S 5 (0 = x ≤ 0.10) samples are crystallized in singlephase monoclinic structure. The electrical resistivity and magnetic measurements of Nb2Pd1?xNix S 5 (0 = x ≤ 0.15) were carried out to study the variation of superconducting critical parameters with Ni doping. Superconductivity in Nb2PdS5 sample completely disappears for x ≥ 0.15. We observed that the ratio of upper critical field to transition temperature decreases with increasing Ni concentration. Also, the magnetization study of Nb2Pd1?xNix S 5 (0 = x ≤ 0.15) samples shows similar superconducting behaviour. In summary, the superconductivity in Nb2PdS5 sample is slightly varying with partial doping of Ni at Pd site in Nb2PdS5 superconductor. 相似文献
946.
Gabriela Tenorio L. Bucio R. Escudero 《Journal of Superconductivity and Novel Magnetism》2017,30(9):2381-2386
Z r S e 2 is a band semiconductor studied long time ago. It has interesting electronic properties, and because its layer structure can be intercalated with different atoms to change some of the physical properties. In this investigation, we found that Zr deficiencies alter the semiconducting behavior and the compound can be turned into a superconductor. In this paper, we report our studies related to this discovery. The decreasing of the number of Zr atoms in small proportion according to the formula Zr x Se2, where x is varied from about 8.1 to 8.6 K, changing the semiconducting behavior to a superconductor with transition temperatures ranging between 7.8 and 8.5 K, is depending on the deficiencies. Outside of those ranges, the compound behaves as semiconducting with the properties already known. In our experiments, we found that this new superconductor has only a very small fraction of superconducting material determined by magnetic measurements with applied magnetic field of 10 Oe. Our conclusions is that superconductivity is filamentary. However, in one studied sample, the fraction was about 10.2 %, whereas in others is only about 1% or less. We determined the superconducting characteristics; the critical fieldsthat indicate a type 2 superonductor with Ginzburg-Landau κ parameter of the order about 2.7. The synthesis procedure is quite normal following the conventional solid state reaction. In this paper, included are the electronic characteristics, transition temperature, and evolution with temperature of the critical fields. 相似文献
947.
A Mussel‐Inspired Conductive,Self‐Adhesive,and Self‐Healable Tough Hydrogel as Cell Stimulators and Implantable Bioelectronics 下载免费PDF全文
948.
Nutrient monitoring is very important for the area of food–energy–water nexus. The sensor network for nutrient monitoring requires dynamic sensing where the positions of the sensors change with time. In this work, we have proposed a methodology to optimize a dynamic sensor network which can address the spatiotemporal aspect of nutrient movement in a watershed. This is a first paper in the series where an algorithmic and methodological framework for spatiotemporal sensor placement problem is proposed. Dynamic sensing is widely used in wireless sensors, and the current approaches to solving this problem are data intensive. This is the first time we are introducing a stochastic optimization approach to dynamic sensing which is efficient. This framework is based on a novel stochastic optimization algorithm called Better Optimization of Nonlinear Uncertain Systems (BONUS). A small case study of the dynamic sensor placement problem is presented to illustrate the approach. In the second paper of this series, we will present a detailed case study of nutrient monitoring in a watershed. 相似文献
949.
Mariano J. Savelski C. Stewart Slater Paul V. Tozzi Christian M. Wisniewski 《Clean Technologies and Environmental Policy》2017,19(10):2467-2477
This study explores design alternatives for the purification and possible reuse of low-volume organic solvents waste streams in pharmaceutical manufacturing. Solvent use has a large impact on the life cycle of pharmaceutical processes, as typically 80–90% of the total mass used in the production of an active pharmaceutical ingredient is attributed to solvent use. Solvents are not consumed in pharmaceutical processes so they exit the process as waste. These waste streams are usually disposed of using incineration; therefore, generating significant life cycle emissions from disposal and replacement of virgin solvent. Solvent recovery efforts are generally limited to large-volume waste streams. However, results show that solvents in low-volume streams can also be economically recovered using a versatile multi-campaign solvent recovery skid. Three different solvent waste streams were evaluated, and 85.3% reduction in total emissions and 86.3% reduction in operating costs were achieved. Investment in the solvent recovery system was determined to have a payback period of 4.5 years and a 28% IRR over 10 years. A life cycle impact assessment shows impacts on the human health, ecosystems, and resources categories have been reduced by 82.4, 85.1, and 87.1%, respectively. 相似文献
950.
Sustainable development has become one of the leading global issues over the period of time. Currently, implementation of sustainability in supply chain has been continuously in center of attention due to introducing stringent legislations regarding environmental pollution by various governments and increasing stakeholders’ concerns toward social injustice. Unfortunately, literature is still scarce on studies considering all three dimensions (economical, environmental and social) of sustainability for the supply chain. An effective supply chain network design (SCND) is very important to implement sustainability in supply chain. This study proposes an uncertain SCND model that minimizes the total supply chain-oriented cost and determines the opening of plants, warehouses and flow of materials across the supply chain network by considering various carbon emissions and social factors. In this study, a new AHP and fuzzy TOPSIS-based methodology is proposed to transform qualitative social factors into quantitative social index, which is subsequently used in chance-constrained SCND model with an aim at reducing negative social impact. Further, the carbon emission of supply chain is estimated by considering a composite emission that consists of raw material, production, transportation and handling emissions. In the model, a carbon emission cap is imposed on total supply chain to reduce the carbon footprint of supply chain. To solve the proposed model, a code is developed in AMPL software using a nonlinear solver SNOPT. The applicability of the proposed model is illustrated with a numerical example. The sensitivity analysis examines the effects of reducing carbon footprint cap, negative social impacts and varying probability on the total cost of the supply chain. It is observed that a stricter carbon cap over supply chain network leads to opening of more plants across the supply chain. In addition, carbon footprint of supply chain is found to be decreased in certain extent with the reduction in negative social impacts from suppliers. The carbon footprint of the supply chain is found to be reduced with increasing certainty of material supply from the suppliers. The total supply chain cost is observed to be augmented with increasing probability. 相似文献