The Magnetic Behavior and Physical Characterization of?Cu�CMn�CAl Ferromagnetic Shape Memory Alloy

In this study, Cu?CAl?CMn alloys with different weight percentages were fabricated by melting metal powders in an induction furnace under argon atmosphere and then by applying rapid solidification. Due to the changes of the alloy percentages after the casting processes, alloy rates were determined by using energy-dispersive X-ray spectroscopy results received from least three different zones. For five different samples, the alloy percentages were found as Cu?C11.96%Al?C3.21%Mn, Cu?C14.09%Al?C10.78%Mn, Cu?C13.73%Al?C13.12%Mn, Cu?C13.44%Al?C12.68%Mn and Cu?C12.14%Al?C15.67%Mn, respectively. The magnetic properties of CuAlMn alloys were investigated as a function of Mn concentration. From the measurements, two important properties were observed. One of them is the temperature-dependent behavior, which indicates that the Curie temperatures of the samples are high (they are in the range of 304?C344?°C). The other property is the saturation magnetization, which is highly dependent on the Mn concentration. Although the Mn atoms want to cluster and interact antiferromagnetically, it is observed that the saturation magnetization is increased with increasing Mn concentration in these alloys. From these observations, it is suggested that the magnetic interactions in our samples are mostly due to the Mn and Al centers.     

Coexistence of Superconductivity and Ferromagnetic Phases in YBa2Cu3O7−δ Nanoparticles

High-temperature superconductor YBa₂Cu₃O_7?δ (YBCO) nanopowders were synthesized by the citrate-gel route, which is a modification of the sol-gel method. The fine powders were calcinated at 860 and 900 °C. They were of small size, in the range of 30–35 nm. X-ray diffraction (XRD) patterns verified production of the orthorhombic superconducting phase in all samples. Measuring the magnetic properties of these nanoparticles at room temperature, via a vibrating sample magnetometer (VSM), indicated ferromagnetism behavior in the YBa₂Cu₃O_7?δ nanoparticles. As the size of the nanoparticles decreased, the magnetic saturation of all samples increased. The development of the ferromagnetism effect was attributed to the presence of surface oxygen vacancies that lead to electron redistribution on the different ions at the surface. Thus, in an innovative work, the produced samples were annealed at 700 °C for 5 h under 0.8–0.9 bar of air atmosphere. The results showed that a small increase in the nanoparticle size provided a dramatic increase of magnetic saturation in all samples. Thus, we can say that the annealing process at vacuum improves the ferromagnetic properties of YBCO nanoparticles.     

Vibrational measurements of Na/Ni(111) and (Na + CO)/Ni(111)

The vibrational properties of Na atoms and of Na coadsorbed with CO on Ni(111) have been studied by high-resolution electron energy loss spectroscopy. Loss measurements showed a significant weakening of the alkali–substrate bond as a function of the alkali coverage. Moreover, we found that coadsorbed CO molecules dramatically influence the vibrational properties of Na adatoms. The Na–Ni stretching frequency (22 meV) measured on the Na/Ni(111) system shifted down to 13 meV for the (Na + CO)/Ni(111) surface. This unexpected result was ascribed to a charge transfer from Na to CO. Present findings give new insights on the nature of the alkali–substrate and alkali–CO bond.     

Physical and Magnetic Properties of Nd1?x Gd x Ni4B Compounds

We have produced Nd_1?x Gd _x Ni₄B (0??x??1.0) compounds by the arc-melting method. Physical properties of the produced samples have been investigated by means of the X-ray powder diffraction, zero field/field cooled magnetization between the temperature interval of 9?C70 K, and magnetic hysteresis at 9.5 K. We have observed that the substitution of Gd for Nd leads to a decrease of the unit-cell parameters a, c and the unit-cell volume V. The magnetic phase transition temperatures are found to be 12, 14, 18, 24, 29 and 35 K, for x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, respectively.     

New Cubic Phases in the Li–Na–Sb–Bi System

New compounds with the general formula A _x A"_3-x B _y B"_1-y (A, A" = Li, Na; B, B" = Sb, Bi) were prepared in the system Li–Na–Sb–Bi. Na₃Sb_0.5Bi_0.5has a hexagonal structure (Na₃As type, a= 5.415 Å, c= 9.595 Å), and Li₃Sb_0.5Bi_0.5and Li₂NaSb_0.5Bi_0.5have a cubic structure (BiF₃type, a= 6.645 and 6.772 Å, respectively). The phase transitions of alkali-metal pnictides were studied by in situ x-ray diffraction at room temperature and pressures from 10⁵Pa to 9.0 GPa. Li₃Sb and Na₃Sb were each shown to exist in two polymorphs with hexagonal (Na₃As type) and cubic (BiF₃type) structures. At atmospheric pressure, Li₃Sb undergoes an irreversible – phase transition at 650°C, while Na₃Sb undergoes a reversible transformation into a cubic phase at 2.3 GPa and room temperature.     

Nucleation and Formation of Stable and Metastable Phases in Undercooled AI-Li Melts

A modified nucleation and competitive growth kinetic theory considering unsteady nucleation andeffect of composition in dilute binary alloys was suggested,based on which the selections of δ.δ'and α phases in undercooled Al-Li melts were summarized by both isothermal and continuous cool-ing treatment methods.     

Physicochemical Properties of L-Alanine in Aqueous Silver Sulphate Solutions at (298.15, 308.15, and 318.15)?K

Apparent molar volumes ${(\varphi_V)}$ and viscosity B coefficients for L-alanine in (0.005, 0.010, 0.015, and 0.020) mol · dm^?3 aqueous silver sulphate (Ag₂SO₄) solutions were determined from the solution density and viscosity measurements at (298.15, 308.15, and 318.15) K as a function of amino acid concentration. The standard partial molar volumes ${(\varphi_V^0)}$ and experimental slopes ${(S_V^\ast )}$ obtained from the Masson equation were interpreted in terms of solute?Csolvent and solute?Csolute interactions, respectively. To analyze solution viscosities in terms of viscosity B coefficients, the Jones?CDole equation was applied. The structure-making or -breaking ability of the amino acid has also been discussed in terms of the sign of ${(\delta^{2}\varphi_V^0/\delta T^{2})_{P}}$ . The activation parameters of viscous flow for the ternary solutions were also derived and explained in terms of transition state theory.     

Negative Magnetization and Superconductivity in the (LaPt2Asx (x = 1, 2) and BaPt2As2 Compounds

Journal of Superconductivity and Novel Magnetism - We have investigated the electrical and magnetic properties of the compounds LaPt2As, LaPt2As2, and BaPt2As2 prepared by conventional solid-state...     

First-Principle Investigations of Structural,Electronic, and Half-Metallic Ferromagnetic Properties in In1−xTM x P (TM = Cr,Mn)

First-principle calculations within the framework of density functional theory are employed to study the structural, electronic, and half-metallic ferromagnetic properties of In_1?x (TM) _x P (TM = Cr, Mn) at concentrations (x = 0.0625, 0.125, 0.25)of transition metal in zinc blende phase. The investigations of electronic and magnetic properties indicate that In_1?xTM _x P (TM = Cr, Mn) at x = 0.0625, 0.125, and 0.25 are half-metallic ferromagnets with 100 % magnetic spin polarization. On the one hand, the total magnetization is an integer Bohr magneton of 3 μ _B and 4 μ _B for In_1?xCr _x P and In_1?xMn _x P, respectively, which confirms the half-metallic feature of In_1?xTM _x P compounds. On the other hand, the densities of states of majority-spin states show that the large hybridization between 3p (P) and 3d (TM) partially filled states dominates the gap, which stabilizes the ferromagnetic state configuration associated with double-exchange mechanism. The band structures depict that half-metallic gap at x = 0.0625 is 0.404 eV for In_1?xCr _x P which is higher than 0.125 eV for In_1?xMn _x P. Therefore, the largest half-metallic gap in In_1?xCr _x P at low concentration x = 0.0625 reveals that Cr-doped InP seem to be a more potential candidate than that Mn-doped InP for spin injection applications in the field of spintronic devices.     

Study on oxidation behavior of (Nd,Y)- and (Nd,Yb)-α-Sialon

The oxidation behavior of multi-cation -Sialons containing Nd and Y or Yb has been investigated for the compositions (Nd_0.18Y_0.18)Si_10.38Al_1.62O_0.54N_15.46 and (Nd_0.18Yb_0.18)Si_10.38Al_1.62O_0.54N_15.46 respectively in the temperature range of 1200°C to 1400°C in air. The grains of silicate containing Nd and Y as well as Nd and Yb were observed in preferred orientation on the surface of the materials oxidized at 1200°C or 1300°C for 20 h for (Nd,Y)- and (Nd,Yb)--Sialon respectively. By increase of oxidation temperature from 1300°C to 1400°C, bubble, which was caused by softening of silicate oxidation layer, occurred and glassy phase then appeared obviously. The phases formed on the surfaces of multi-cation -Sialons during the oxidation were also discussed in this paper.     

Structural, Electronic and Magnetic Properties of Nanolayer and?Bulk of MnCo2Si and MnFeCoSi Compounds

In the present work we have investigated the structural, electronic and magnetic properties of MnCo₂Si and MnFeCoSi in bulk and nanolayer using density functional theory. The total energies as a function of volume are calculated and thereby the bulk modulus and their pressure derivatives are determined. The effect of atoms at the surface of these nanolayers has been analyzed using the calculated total and partial electron density of states in its ferromagnetic phase. The spin-polarized density of states show that both bulk MnCo₂Si and MnFeCoSi present a half-metallicity, which is lost at their nanolayer surfaces. Furthermore, the effects of pressure on the magnetic moment of these compounds in its bulk form are investigated.     

Li–CO2 and Na–CO2 Batteries: Toward Greener and Sustainable Electrical Energy Storage

Metal–CO₂ batteries, especially Li–CO₂ and Na–CO₂ batteries, offer a novel and attractive strategy for CO₂ capture as well as energy conversion and storage with high specific energy densities. However, some scientific issues and challenges existing restrict their practical applications. Here, recent progress of crucial reaction mechanisms on cathodes in Li–CO₂ and Na–CO₂ batteries are summarized. The detailed reaction pathways can be modified by operation conditions, electrolyte compositions, and catalysts. Besides, specific discussions from aspects of catalyst design, stability of electrolytes, and anode protection are presented. Perspectives of several innovative directions are also put forward. This review provides an intensive understanding of Li–CO₂ and Na–CO₂ batteries and gives a useful guideline for the practical development of metal–CO₂ batteries and even metal–air batteries.     

Safety evaluation of nanodiamond-doxorubicin complexes in a Na?ve Beagle canine model using hematologic,histological,and urine analysis

While doxorubicin(DOX)is one of the most common chemotherapeutic drugs for treating cancer,use of DOX must be managed carefully due to dose-related toxicity.Nan...     

Stability of Phases in SiC and Si_3N_4 Whisker Formation

The stability of the phases in equilibrium is calculated and discussed in order to analyse and predict thereactions in SiC and Si_3N_4 whisker formation.Equilibria among SiC,Si_3N_4,Si_2N_2O,SiO_2 and the gas phaseare evaluated at different C activity,N_2 pressure,and temperature.According to the phase stabilitydiagrams,Si_3N_4 whisker was formed with the increase of N_2 pressure and decrease of C activity;SiC whiskerwas stable with the increase of C activity and decrease of N_2 pressure.In order to control the impure phasesduring the whisker formation,O_2 partial pressure is the most important factor.     

Combustion Synthesis, Powder Characteristics and Crystal Structure of Phases in Ce–Pr–O System

The combustion method has been employed to produce homogeneous, single phased mixed rare-earth oxides in Ce1 – xPrxO2–y system for x ranging from 0 to 0.7. A cubic fluorite structure is formed for the compositions 0 x 0.7, while for x > 0.7 mixed phases are obtained. The mixed oxides are formed at the furnace temperature of 500 °C in a short duration of 10 min. In view of the importance of these powders in catalysis, crystallite size, surface area and porosity measurements have been carried out. The crystallite size of the powders increases with x while the surface area decreases. As the temperature is increased to 850 °C, the surface area decreases and the effect is much pronounced in cerium rich oxides. The powders on calcination above 900 °C in air results in the demixing of Ce and Pr to give two fluorite phases.     

Investigations of Structural, Electronic, and Half-metallic Ferromagnetic Properties in (Al, Ga, In)1−x M x N (M = Fe, Mn) Diluted Magnetic Semiconductors

We investigate the structural, electronic, and magnetic properties of (M = Fe, Mn)-based zinc blende diluted magnetic semiconductors (DMS) (Al, Ga, In)_1?x M _x N for (x=0.0625,0.125,0.25), using first-principles calculations with the full-potential linearized augmented plane waves (FP-LAPW) method within the density functional theory and local spin-density approximation. The analysis of electronic structures and magnetic properties show that (Al, Ga, In)_1?x Fe _x N at (x=0.0625,0.125,0.25) are magnetic insulators, and In_1?x Mn _x N at (x=0.0625,0.125) are metallic in nature. On the other hand the (Al, Ga)_1?x Mn _x N at (x=0.0625,0.125,0.25) and In_0.75Mn_0.25N are half-metallic ferromagnets with magnetic spin polarization of 100 %, where the ferromagnetic ground states result from a double-exchange mechanism, and these compounds are predicted to be good candidates for spintronic applications.     

Disordered Vortex Phases in YBa2Cu3O7?δ

The disordered vortex phases induced by line and point pinning in YBa₂Cu₃O_7– are explored. At high defect densities, only a single disordered solid separated from the liquid phase by a melting line is observed. At low defect densities the topology of the phase diagram changes dramatically, with a vortex lattice phase adjoining disordered phases at high or low field. Critical points at the termination of the first-order melting line separate the lattice and the disordered phases. The line defect disordered phases follow the expected Bose glass behavior, while the point defect disordered phases do not exhibit the expected vortex glass behavior.