Influence of Mg21Ga5Hg3 compound on electrochemical properties of Mg-5%Hg-5%Ga alloy

The Mg-Hg-Ga alloys are widely used in high power the seawater batteries. Mg-5%Hg-5%Ga alloy was melted and heat treatments at 573-773 K were performed for different times. The electrochemical and corrosion behaviors of the Mg-5%Hg-5%Ga alloy were studied by means of potentiodynamic, galvanostatic and electrochemical impedance spectroscopy(EIS). Scanning electron microscopy(SEM), energy dispersive spectrometry(EDS) and X-ray diffractometry(XRD) were employed to characterize the microstructures of the alloy. The results demonstrate that the best electrochemical activity occurs in the Mg-5%Hg-5%Ga alloy with homogeneously dispersed Mg21Ga5Hg3 compound in α-Mg matrix. The most negative mean potential at 100 mA/cm2 polarization current density can reach -1.928 V. The largest corrosion current density 19.37 mA/cm2 of the Mg-5%Hg-5%Ga alloy appears in the Mg-5%Hg-5%Ga alloy with intergranular eutectic α-Mg and Mg21Ga5Hg3.     

Crystal structure and Rietveld refinement of the new ternary compound Al14Nd5Si

The new ternary compound Al14Nd5Si has been studied by means of the X-ray powder diffraction technique and the Rietveld method. The ternary compound Al14Nd5Si has a hexagonal Ni3Sn-type structure with space group P63/mmc (No.194), the lattice parameters are a = 0.64470 (2) nm and c = 0.45926 (1) nm. The Smith and Snyder figure of merit for the index, FN, is F30 = 97.8 (30). The X-ray diffraction data indicated that the crystal structure of the compound Al14Nd5Si has been successfully refined by the Rietveld method. The R-factors of Riet- veld refinement are Rp = 0.088 and Rwp = 0.120, respectively. The thermal dependence of magnetization for the compound was measured by a vibrating sample magnetometer. The experimentally determined magnetic effective paramagnetic moment is μeff = 3.60 μB per Nd atom. The paramagnetic Currie temperature θp = -33.7 K was also obtained from the Currie-Weiss law.     

Crystal structure and Rietveld refinement of the new ternary compound Al14Nd5Si

The new ternary compound Al₁₄Nd₅Si has been studied by means of the X-ray powder diffraction technique and the Rietveld method. The ternary compound Al₁₄Nd₅Si has a hexagonal Ni₃Sn-type structure with space group P6₃/mmc (No.194), the lattice parameters are a = 0.64470 (2) nm and c = 0.45926 (1) nm. The Smith and Snyder figure of merit for the index, F_N, is F₃₀ = 97.8 (30). The X-ray diffraction data indicated that the crystal structure of the compound Al₁₄Nd₅Si has been successfully refined by the Rietveld method. The R-factors of Rietveld refinement are R_p = 0.088 and R_wp = 0.120, respectively. The thermal dependence of magnetization for the compound was measured by a vibrating sample magnetometer. The experimentally determined magnetic effective paramagnetic moment is μ_eff = 3.60 μ_B per Nd atom. The paramagnetic Currie temperature θ_p = −33.7 K was also obtained from the Currie-Weiss law.     

Electronic structure of the new manganese ternary hydride Mg3MnH7

We have investigated the electronic structure of the new manganese hydride Mg₃MnH₇ by calculating ab initio the energy bands, density of states and the partial wave analysis of the density of states at each atomic site. We found that this hydride is an insulator with a large indirect energy gap of 2.56 eV. Partial wave analysis of the density of states shows that the electronic properties of this compound are strongly dominated by the bonding features of the MnH₆ and Mg₂H units.     

Crystal structure of the new ternary germanide Tb4Zn5Ge6

The Tb₄Zn₅Ge₆ phase was prepared by arc melting in an argon atmosphere and then annealed at 670 K for 400 h. The structure of orthorhombic Tb₄Zn₅Ge₆ was determined by single-crystal X-ray diffraction (Cmc2₁, Z = 4, a = 4.2330(10) Å, b = 18.576(4) Å, c = 15.275(3) Å, R₁ = 0.0272 and wR₂ = 0.1076). The structure is isostructural to Gd₄Zn₅Ge₆ and composed of edge- and corner-sharing ZnGe₄ tetrahedra, Tb-atoms forms trigonal prisms filled by Ge-atom.     

Crystal structure of the new compound Ce3Pt23Si11

The crystal structure of the new ternary compound, Ce₃Pt₂₃Si₁₁, was determined by X-ray analysis of a single crystal (Enraf-Nonius CAD-4 diffractometer, Mo Kα radiation, 585 independent reflections, R=0.0487). The Ce atoms have only one crystallographic position with a very rare tetragonal prism coordination polyhedron.     

Crystal structure and properties of the new ternary YbZnxGa4−x and Yb3Zn11−xGax phases

Crystal structures of three new ternary YbZn_xGa_4?x (0.25 ≤ x ≤ 0.5 and 0.75 ≤ x ≤ 2) and Yb₃Zn_11?xGa_x (3.5 ≤ x ≤ 4.2) phases have been determined by means of single crystal X-ray as well as powder diffraction. They crystallize in known structure types, namely: CaCu_0.15Ga_3.75, BaAl₄ and La₃Al₁₁. Magnetic and transport properties were investigated for the new YbZn_xGa_4?x compounds. All phases studied show metallic-like and diamagnetic behavior.     

Crystal structure and physical properties of a new intermetallic compound URu2Al10

We report on the existence in the U–Ru–Al system of a novel compound, URu₂Al₁₀, crystallizing in the orthorhombic YbFe₂Al₁₀-type structure, where the uranium atoms are caged in Ru–Al polyhedra, forming a clathrate-like structure. Results of the magnetic susceptibility, electrical resistivity in zero and in magnetic fields up to 8 T, thermopower and specific heat, performed in a wide temperature range, are presented. No magnetically ordered state down to the lowest temperature measured has been found. On the basis of (i) the susceptibility anomaly occurring at about 50 K and (ii) the positive magnetoresistivity, growing with applied magnetic field as αBⁿ (n ≈ 3/2), (iii) a characteristic temperature variation of the thermopower, as well as (iv) a moderate value of the Sommerfeld coefficient, a mixed-valence state of uranium in this compound has been postulated. This points to similarities between the presently studied compound and the behaviour of other Ru-containing uranium ternaries, such as U₂Ru₂Sn and U₂RuGa₈, classified earlier as valence-fluctuating type materials.     

Magnetic properties of the new rare earth intermetallic compound Pr5AgSn3

A detailed structural characterisation, by means of the powder X-ray diffraction method, of the new Pr₅AgSn₃ intermetallic compound has been performed and a.c., d.c. magnetic measurements in the 4-300 K temperature range and in applied magnetic fields up to 9 Tesla have been obtained and analysed. The compound orders ferromagnetically below 33.5 K and exhibits a pronounced hysteresis cycle at 5 K with a saturation magnetisation (μ_sat) of 1.84 μ_B/Pr atom. In the paramagnetic state the compound follows the Curie-Weiss law with μ_eff.=3.40 μ_B and θ_P=+32 K. The splitting of the peak in the a.c. susceptibility by applied low d.c. fields as well as the temperature dependence of the remanence (B_r) and of the coercive field (H_c) are tentatively explained in terms of domain dynamics.     

Crystal structure,electrical, and magnetic properties of the Sm2Cu0.8Ge3 compound

The crystal structure, electrical, and magnetic properties of the new ternary compound Sm₂Cu_0.8Ge₃ have been investigated using powder X-ray diffraction, electrical resistivity, and magnetic susceptibility measurements. X-ray diffraction patterns reveal that this compound crystallizes in a tetragonal α-ThSi₂ structure (space group I4₁/amd) with lattice parameters a = 0.413(1) nm and c = 1.420(3) nm. The irreversibility of the zero field cooled and field cooled dc magnetization data reveals the occurrence of spin glass transition with the spin freezing temperature T_f ∼ 8.5 K in this compound. Ac susceptibility and isothermal remanent magnetization data also confirm the existence of the spin glass phase. In addition, a broad maximum is observed in the ρ(T) curve near T_f. The spin glass phase is ascribed to the formation of random interaction between the Sm ions due to the irregular distribution of Cu and Ge atoms as well as the deficiency of the occupancy on the 8e crystallographic sites of the sample.     

Crystal structure of the Hg4SiS6 and Hg4SiSe6 compounds

The crystal structures of Hg₄SiS₆ and Hg₄SiSe₆ compounds were investigated using X-ray powder diffraction. These compounds crystallize in the monoclinic Cc space group with the lattice parameters a=1.23020(5), b=0.71031(4), c=1.22791(4) nm, β=109.721(3)° for Hg₄SiS₆ and a=1.28110(4), b=0.74034(4), c=1.27471(1) nm, β=109.605(3)° for Hg₄SiSe₆. Atomic parameters were refined in the isotropic approximation (R_I=0.0571 and R_I=0.0555 for the Hg₄SiS₆ and Hg₄SiSe₆, respectively).     

Hg和Ga元素对Mg阳极材料组织和电化学腐蚀性能的影响(英文)

采用动电位极化、恒电流和交流阻抗测试方法研究了Hg和Ga元素对Mg2%Hg,Mg2%Ga和Mg2%Hg2%Ga合金电化学腐蚀性能的影响,并用扫描电镜、X射线衍射和能谱分析了上述合金的显微组织和腐蚀表面形貌。结果表明:Mg2%Ga合金是固溶体,Mg-2%Hg和Mg-2%Hg2%Ga合金的晶界有白色第二相。Mg-2%Ga合金的平均电位为1.48V,腐蚀电流密度为0.15mA/cm2,电化学活性差,耐腐蚀性能好。Mg-2%Hg-2%Ga合金的平均电位1.848V,腐蚀电流密度为2.136mA/cm2,电化学活性好,耐腐蚀性能差。MgHgGa合金的活化机制是Hg和Ga原子的溶解沉积。     

Magnetic structure of the Mn5Si3-type Er5Si3 compound

Neutron diffraction study has been performed on the Er₅Si₃ compound (hexagonal Mn₅Si₃-type, hP16, P6₃/mcm) to understand its magnetic structure. The temperature dependent neutron diffraction results prove that this compound shows a complex antiferromagnetic ordering with sine modulated magnetic moments collinear to the c axis, presenting three subsequent changes in magnetization at ～29 K, 13 K and 10 K on cooling. The high-temperature magnetic component of Er₅Si₃ (C_3v magnetic point group, P31m magnetic space group, K₁ = [0, 0, ±0.277(2)]) exists from 29 K to 10 K, whereas low-temperature magnetic component (symmetry C_1v magnetic point group, Pm magnetic space group, K₂ = [0, ±1/4, 0]) exists from 13 K down to 1.5 K. The low-temperature and high-temperature magnetic components coexist between 13 K and 10 K.     

Influence of aging treatments on microstructure and electrochemical properties in Mg–8.8Hg–8Ga (wt%) alloy

All precipitate morphologies in Mg–8.8%Hg–8%Ga alloy for a range of aging temperatures are investigated in detail using SEM, TEM and OM. The results show that Mg₂₁Ga₅Hg₃ are the dominant precipitate in Mg–8.8%Hg–8%Ga alloy. Mg₂₁Ga₅Hg₃ phase precipitate in dispersed particles. There are few papers focuses on the relationship between the aging behavior and the electrochemical and corrosion properties in Mg–8.8%Hg–8%Ga alloy. This study elaborates on the morphological evolution of Mg₂₁Ga₅Hg₃ precipitates as a function of aging time and temperature and investigates the associated second phase morphology-electrochemical and corrosion response. The corrosion behavior of the Mg–8.8%Hg–8%Ga alloy is also discussed.     

Crystal structure and electronic properties of new uranium intermetallic compound UGa1.85Zr0.15

The intermetallic compound UGa_1.85Zr_0.15 does not crystallize in the AlB₂ structure shared by UGa₂ and UZr₂. Instead, it forms in the same orthorhombic structure as U₃Ga₅ (Pu₃Pd₅ type), but the somewhat smaller lattice parameters reduce the unit cell volume by 2.1% with respect to U₃Ga₅. Basic magnetic properties, namely the ferromagnetic ground state below T_C = 23 K, are similar to U₃Ga₅. A more detail study of magnetic properties reveals interesting metamagnetic behavior with a critical field of 2–3 T, which increases with increasing temperature. The high γ-value of 110 mJ mol⁻¹ K⁻² points to a narrow 5f band at Fermi level.     

Electronic structure and properties of LaNi_5 compound from first principles

The energy,electronic structure,and magnetic and mechanical properties of LaNi5 compound have been studied by the first-principles method based on the density functional theory.The results show that the calculated lattice parameters of LaNi5 compound are almost the same with the experimental ones,and the compound is easy to form and very stable.The bond between La and Ni1 atoms is an ionic bond,and electrostatic attraction effect exists between Ni atoms.The farther the distance between Ni atoms in the LaNi5 crystal cell is,the stronger the electrostatic attraction effect is.LaNi5 intermetallic compound is ductile and ferromagnetic.The calculated hardness value of LaNi5 compound is 7.04 GPa,and the calculated elastic properties are close to the experimental results.     

Crystal structure, thermal expansion and electrical properties of the new Al0.32ErGe2 compound

A new ternary compound Al_0.32ErGe₂ has been synthesized and studied from 298 K to 773 K using X-ray powder diffraction technique. Its structure has been determined at room temperature by Rietveld refinement of X-ray powder diffraction data. The ternary compound Al_0.32ErGe₂ crystallizes in the orthorhombic with the defect CeNiSi₂ structure type (space group Cmcm, a = 0.40701(2) nm, b = 1.60401(9) nm, c = 0.39240(2) nm, Z = 4 and D_calc = 8.326 g/cm³). The average thermal expansion coefficients , and of Al_0.32ErGe₂ are 1.72 × 10⁻⁵ K⁻¹, 1.11 × 10⁻⁵ K⁻¹ and 1.52 × 10⁻⁵ K⁻¹, respectively. The bulk thermal expansion coefficient is 4.35 × 10⁻⁵ K⁻¹. Electrical resistivity of Al_0.32ErGe₂ was measured between 5 K and 300 K.     

Crystal structure and magnetic properties of the new ternary actinide compounds AnPd5Al2 (An = U, Np)

We report the crystal structure and magnetic properties of new ternary actinide compounds UPd₅Al₂ and NpPd₅Al₂. Both compounds crystallize in the body-centered tetragonal ZrNi₂Al₅-type tetragonal structure (I 4/mmm). Although the magnetic susceptibility of both compounds follows the Curie–Weiss behavior at high temperature, no magnetic phase transition was observed. UPd₅Al₂ has a nonmagnetic ground state where the magnetic susceptibility saturates at low temperature, while NpPd₅Al₂ superconducts below 4.9 K as reported recently.