Phase equilibria in the AlVO4-Al2(MoO4)3 system

The phase equilibria established in the AlVO₄-Al₂(MoO₄)₃ system over the whole component concentration range up to 1000 °C have been investigated. A phase diagram has been constructed using the results of DTA and XRD methods. The AlVO₄-Al₂(MoO₄)₃ system is not a true two-component system, even in the subsolidus area.     

Growth and spectroscopic properties of Nd-doped Na2Gd4(MoO4)7 crystal

This paper reports the growth and spectral properties of Nd³⁺:Na₂Gd₄(MoO₄)₇ crystals. An Nd³⁺:Na₂Gd₄(MoO₄)₇ crystal with dimensions of Ø20 × 25 mm³ has been grown by the Czochralski method. The spectroscopic properties of Nd³⁺:Na₂Gd₄(MoO₄)₇ crystal were investigated. The Judd-Ofelt theory was applied to calculate the spectral parameters. The polarized absorption cross-sections of Nd³⁺:Na₂Gd₄(MoO₄)₇ crystal are 4.25 × 10⁻²⁰ cm² with full width at half maximum (FWHM) of 14.6 nm for the π-polarization and 2.87 × 10⁻²⁰ cm² with FWHM of 16.2 nm for the σ-polarization, respectively. The emission cross-sections are 10.0 × 10⁻²⁰ cm² at 1060 nm for π-polarization and 13.6 × 10⁻²⁰ cm² at 1067 nm for σ-polarization, respectively. The fluorescence quantum efficiency has been estimated to be 90.0%. Nd³⁺:Na₂Gd₄(MoO₄)₇ crystal may be considered as a potential laser gain medium for the diode laser pumping.     

Spectroscopic investigation of Dy-doped Li2Gd4(MoO4)7 crystal for potential application in solid-state yellow laser

Dy³⁺:Li₂Gd₄(MoO₄)₇ crystal with dimensions of ∅20 × 25 mm³ has been grown by the Czochralski method. The spectroscopic properties of Dy³⁺:Li₂Gd₄(MoO₄)₇ crystal have been investigated. Based on the analysis of polarized absorption spectra in the framework of the Judd-Ofelt theory, the main spectroscopic characteristics, including the phenomenological intensity parameters, spontaneous transition probabilities, fluorescence branching ratios and radiative lifetimes of Dy³⁺ in the crystal, have been determined. The emission cross-sections for the ⁴F_9/2 → ⁶H_13/2 transition of special interest for laser application have been calculated using the Füchtbauer-Ladenburg (F-L) equation. The fluorescence and radiative lifetimes of ⁴F_9/2 manifold are equal to 126.5 μs and 201.1 μs, respectively, which mean the quantum efficiency is 62.9%. The results propose the possibility of Dy³⁺:Li₂Gd₄(MoO₄)₇ crystal for solid-state yellow laser pumped by commercially available blue laser diodes.     

Mechanical and thermal properties of Tb2(MoO4)3 crystals

The mechanical and thermal properties of single crystal Tb₂(MoO₄)₃ have been systematically studied. The result of microhardness measurement indicates that the crystal belongs to the soft materials category. The thermodynamic parameters obtained from DTA analysis were used for determining the type of liquid-solid interface during crystal growth. Negative thermal expansion along the c-axis was observed, and this behavior was attributed to the bent Tb-O-Mo bonds. The specific heat of the crystal was measured to be 0.122 cal g⁻¹ K⁻¹ at 293.15 K. The thermal conductivity of Tb₂(MoO₄)₃ at room temperature was found to be smaller than that of representative ferroelectric LiNbO₃.     

Subsolidus phase relations in the system ZnO–P2O5–MoO3

The subsolidus phase relations of the ternary system ZnO–P₂O₅–MoO₃ were investigated by means of X-ray diffraction (XRD). Seven binary compounds and eight 3-phase regions were determined, and no ternary compound was found in this system. The phase diagram of pseudo-binary system Zn₃(PO₄)₂–Zn₃Mo₂O₉ was also constructed through XRD and differential thermal analysis (DTA) methods, and the result reveals this system is eutectic system. The eutectic temperature is 904 °C and the corresponding component is 30% Zn₃Mo₂O₉ and 70% Zn₃(PO₄)₂.     

Interaction between MoO3 and metals Te, Cd, Sb

Eighteen compositions of MoO₃-Te at 800 °C and seven of each of MoO₃-Cd (at 500 °C) and MoO₃-Sb (at 600 °C) were heat treated in vacuum-sealed quartz ampules. The phases of the heat-treated compositions were analyzed using x-ray diffraction (XRD) patterns. The interactions in the three systems are summarized. Three phases in equilibrium are (1) in the MnO₃-Te system at 800 °C, Te, Mo₄O₁₁, TeMo₄O₁₃—(0<x_{MoO 3}<0 889) and MoO₃, Mo₄O₁₁, TeMo₄O₁₃—(0.889<x_{MoO 3}<1); (2) in the MoO₃_Cd system at 500 °C, Cd, MoO₂, CdMoO₄—(0<x_{MoO 3}<0.6667) and MoO₃, MoO₂, CdMoO₄—(0.6667<x_{MoO 3}<1); and (3) in the MoO₃-Sb system at 600 °C, Sb, MoO₂, Sb₄Mo₁₀O₃₁—(0<x_{MoO 3}<0.734) and MoO₃+MoO₂+Sb₄Mo₁₀O₃₁ (0.734<x_{MoO 3}<1). The results lead to construction of ternary phase diagrams: Te-MoO₃-TeMo₄O₁₃, Cd-MoO₃-CdMoO₄, and Sb-MoO₃-Sb₄Mo₁₀O₃₁.     

Multiwavelength excited novel red-emitting phosphor Eu-activated Li2Zn2(MoO4)3

Eu³⁺-activated Li₂Zn₂(MoO₄)₃ multiwavelength excited red-emitting phosphors were synthesized via a solid state reaction. The structure and photoluminescence characteristics were investigated by X-ray powder diffraction and fluorescent spectrophotometry, respectively. The excitation spectrum included a strong broadband ranging from 250 to 350 nm and some sharp peaks at 363, 384, 395, 465, and 533 nm, which matchs the radiations of near-UV or blue light-emitting diodes chip well. Upon excitation either of near-UV or blue even green light, the intense red emission with 615 nm peak can be observed, which is ascribed to the ⁵D₀-⁷F₂ transition of Eu³⁺ ions. The chromaticity coordinates (x = 0.65, y = 0.34) of the as-obtained phosphor is very close to the National Television Standard Committee standard values (x = 0.67, y = 0.33). All these characteristics suggest that Eu³⁺-doped Li₂Zn₂(MoO₄)₃ wavelength-conversion material to be suitable candidate red component for phosphor-converted white light-emitting diodes.     

Concentration-dependent luminescence and energy transfer of flower-like Y2(MoO4)3:Dy phosphor

Flower-like Y₂(MoO₄)₃:Dy³⁺ phosphors have been synthesized via a co-precipitation approach with the aid of β-cyclodextrin. The crystal structure and morphology of the phosphors were characterized by XRD (X-ray diffraction) and FE-SEM (field emission scanning electron microscopy), respectively. The excitation and emission properties of the phosphors were examined by fluorescence spectroscopy. The dependence of color coordinates on the Dy³⁺ doping concentration was analyzed. The energy transfer mechanism between Dy³⁺ ions was studied based on the Huang's theory, I-H and Van Uitert's models. It was concluded simultaneously from these three routes that the electric dipole-dipole interaction between Dy³⁺ ions is the main physical mechanism for the energy transfers between Dy³⁺.     

Preparation and characteristic of spherical Li3V2(PO4)3

Spherical Li₃V₂(PO₄)₃ was synthesized by using N₂H₄ as reducer. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that single-phase, spherical and well-dispersed Li₃V₂(PO₄)₃ has been successfully synthesized in our experimental process. Electrochemical behaviors have been characterized by charge/discharge measurements. The initial discharge capacities of Li₃V₂(PO₄)₃ were 123 mAh g⁻¹ in the voltage range of 3.0–4.3 V and 132 mAh g⁻¹ in the voltage range of 3.0–4.8 V.     

L12型Al3Sc基金属间化合物有序化行为和力学性能的第一性原理计算

本文采用亚晶格模型,辅助以第一性原理总能计算,研究了L1₂型Al₃Sc基金属间化合物中元素的占位有序化行为和力学性能。结果表明：Al₃Sc合金呈现完全有序化,其中Al占据3c亚晶格位置,Sc占据1a亚晶格位置；L1₂-Al₃(Sc_0.75M_0.25)金属间化合物(M=Y、Ti、Zr和Hf)也呈现完全有序化,第三组元M均只占据1a亚晶格位置,这些元素的占位行为均不受温度的影响。L1₂-Al₃(Sc_0.75M_0.25)金属间化合物均满足力学稳定性条件。M为Y时,L1₂-Al₃(Sc_0.75M_0.25)金属间化合物的剪切模量、体弹模量和杨氏模量和硬度下降；M为Ti、Zr或Hf时,随着原子半径增大,剪切模量、体弹模量、杨氏模量和硬度逐渐降低,其中Ti的加入可使L1₂-Al₃(Sc_0.75M_0.25)金属间化合物的塑性和韧性达到最好。     

Sodium molybdate as a corrosion inhibitor for aluminium in H3PO4 solution

The inhibition effect of sodium molybdate (Na₂MoO₄) on the corrosion of aluminium in 1.0 M H₃PO₄ solution was studied by weight loss, potentiodynamic polarisation curves and electrochemical impedance spectroscopy (EIS) methods. The results show that Na₂MoO₄ is a good inhibitor, and the inhibition efficiency obtained by three methods is higher than 84% at 20 mM. The adsorption of Na₂MoO₄ obeys Freundlich isotherm at lower concentrations (1–7 mM), while Langmuir isotherm at higher concentrations (7–20 mM). Polarisation curves indicate that Na₂MoO₄ acts as an anodic inhibitor. EIS spectra exhibit three loops (two capacitive loops and one inductive loop).     

C-MoS2-Fe2O3(Fe3O4)纳米润滑剂对无镀铜焊丝导电嘴磨损的影响

针对无镀铜实心焊丝在机器人自动焊接时导电嘴磨损问题,采用机械涂敷法在无镀铜实心焊丝表面制备了C-MoS₂-Fe₂O₃(Fe₃O₄)纳米复合润滑剂,研究了润滑剂配比对导电嘴磨损性能的影响. 结果表明,C-Fe₃O₄涂层的润滑性能优于C-Fe₂O₃涂层的润滑性能,随着涂层中纳米MoS₂含量的升高,导电嘴的抗磨性能增强. 纳米复合润滑剂在焊丝与导电嘴的摩擦界面发生摩擦化学反应形成了保护性的自修复膜,此膜主要由润滑性能优异的FeO,MoS₂,MoO₃组成,避免了焊丝与导电嘴内表面的直接接触,从而减少了导电嘴的磨损. 氧化磨损、磨粒磨损和电弧烧蚀是导电嘴磨损的主要机制.     

固相-水热法制备LiFePO4-Li3V2（PO4）3复合材料及其电化学性能（英文）

分别采用固相-水热法和球磨法制备磷酸亚铁锂-磷酸钒锂复合正极材料(LiFePO4-Li3V2(PO4)3)。电化学性能测试表明,LiFePO4-Li3V2(PO4)3复合正极材料的电化学性能远远高于 LiFePO4和 Li3V2(PO4)3单独作为正极材料的性能,并且以固相-水热法制备的复合材料性能优于以球磨法制得的复合材料。研究发现 LiFePO4-Li3V2(PO4)3复合材料有 4 个氧化还原峰,相当于 LiFePO4 和 Li3V2(PO4)3 氧化还原峰的叠加。采用固相-水热法制备的LiFePO4-Li3V2(PO4)3 复合材料形貌较为规则,且有新相物质产生,这是导致其电化学性能较好的原因。     

A theoretical analysis of zero-field splitting parameters of Mn doped dicadmium diammonium sulfate Cd2(NH4)2(SO4)3 single crystal

The superposition model (SPM) and crystallographic data are utilized to determine the zero-field splitting (ZFS) parameters (ZFSPs) for Mn²⁺ ions in Cd₂(NH₄)₂(SO₄)₃ single crystal, assuming that the Mn²⁺ ions locate at either Cd²⁺ or NH⁴⁺ site. The SPM results has been verified by the fourth-order perturbation formulae analysis. Experimental suggestions about Mn²⁺ ions substituting at Cd²⁺ sites have been confirmed theoretically for the first time.     

Synthesis and performance of Li3V2(PO4)3/C composites as cathode materials

Carbon-coated Li₃V₂(PO₄)₃ cathode materials for lithium-ion batteries were prepared by a carbon-thermal reduction (CTR) method using sucrose as carbon source. The Li₃V₂(PO₄)₃/C composite cathode materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurement. The results show that the Li₃V₂(PO₄)₃ samples synthesized using sucrose as carbon source have the same monoclinic structure as the Li₃V₂(PO₄)₃ sample synthesized using acetylene black as carbon source. SEM image exhibits that the particle size is about 1 μm together with homogenous distribution. Electrochemical test shows that the initial discharge capacity of Li₃V₂(PO₄)₃ powders is 122 mAh·g⁻¹ at the rate of 0.2C, and the capacity retains 111 mAh−g⁻¹ after 50 cycles.     

Effect of CaTiO3 addition on microwave dielectric properties of Mg2(Ti0.95Sn0.05)O4 ceramics

The microwave dielectric properties of CaTiO₃-added Mg₂(Ti_0.95Sn_0.05)O₄ ceramics prepared by the mixed oxide route have been investigated. The combination of spinel-structured Mg₂(Ti_0.95Sn_0.05)O₄ and perovskite-structured CaTiO₃ forms a two-phase system (1 − x)Mg₂(Ti_0.95Sn_0.05)O₄-xCaTiO₃, which was confirmed by the XRD patterns and the EDX analysis and it also leads to a zero τ_f. The microwave dielectric properties of the ceramics can be effectively controlled by varying the x value. For practical applications, a new microwave dielectric material 0.91Mg₂(Ti_0.95Sn_0.05)O₄-0.09CaTiO₃ is suggested and it possesses a good combination of dielectric properties with an ?_r of ∼18.01, a Q × f of ∼92,000 GHz, and a τ_f of ∼0 ppm/°C, which makes it is a very promising candidate material for high frequency applications.     

Substitutionsvarianten von Nickel(II) amid: ternäre amidoniccolate mit Lithium und Caesium Li3Ni4(NH2)11·NH3 und Cs2Ni(NH2)4·NH3

The red substance Li₃Ni₄(NH₂)₁₁·NH₃ crystallizes from liquid ammonia at room temperature when LiNO₃, LiCl or LiBr reacts with Na₂Ni(NH₂)₄ in a pressure-resistant glass vessel. A similar reaction between CsNH₂ and Ni(NH₂)₂ gives orange crystals of Cs₂Ni(NH₂)₄ ·NH₃. X-ray investigations gave the following data: Li₃Ni₄(NH₂)₁₁·NH₃: Pna2₁; fZ = 4; ; ; ; p(X-ray) = 1.942 g cm⁻³; N(F_o² 3σ(F_o²) = 944; N(Variable) = 157; R/R_w = 0.059/0.072. Cs₂Ni(NH₂)₄ · NH₃: P2₁/c; Z = 4; ; ; ; β = 129.96(3)°; p(X-ray = 2.960 g cm⁻³;N(F_o² 3σ(F_o²) = 1488; N(Variable) = 73; R/R_w = 0.045/0.052. The synthesis, thermal behaviour, IR spectroscopic characteristics and crystal structures of the compounds are reported and comparisons made with Ni(NH₂)₂ and other amidonickel(II) compounds.     

废旧锂离子电池中Li, Fe和V的回收及xLiFePO4-yLi3V2(PO4)3的制备

由于LiFePO_4和Li_3V_2(PO_4)_3材料的特征相近,制备方法类似,提供了一种从废旧LiFePO_4和Li_3V_2(PO_4)_3混合电池中回收Li、Fe和V,再制备xLiFePO_4-yLi_3V_2(PO_4)_3的方法。在空气气氛中600℃热处理1h后,去除粘结剂PVDF使活性物质与集流体分离。调节Li、Fe、V和P摩尔比,球磨、锻烧,配制不同比例的xLiFePO_4-yLi_3V_2(PO_4)_3(x:y=5:1,7:1,9:1)复合电极材料。表征了其形貌、结构和电化学性能,结果表明,回收制备的复合材料将同时具备LiFePO_4和Li_3V_2(PO_4)_3两种材料的电化学性能,能显著改善LiFePO_4的倍率性能。     

An Investigation of the thermal degradation of the intumescent coating containing MoO3 and Fe2O3

An intumescent flame retardant coating was prepared using an ammonium polyphosphate (APP)-pentaerythritol (PER)-melamine (MEL) intumescent flame retardant (IFR) system. Molybdenum trioxide (MoO₃) and ferric oxide (Fe₂O₃) were used as modifiers to improve the thermal stability of the APP-PER-MEL coating. The effects of MoO₃ and Fe₂O₃ on the thermal stability of the residue chars were studied using thermogravimetric analysis (TGA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) and scanning electric microscopy (SEM). The TGA results showed that adding MoO₃ and Fe₂O₃ increased the residue weights of the APP-PER-MEL coatings. XPS analysis demonstrated that the thermal stability of the coatings was improved. SEM images of chars illuminated that MoO₃ and Fe₂O₃ improved the outer and inner surface structure of the residue char layer. All the results indicated that MoO₃ and Fe₂O₃ were effective modifiers to improve the thermal stability of the APP-PER-MEL coating.     

Phase Relations in the Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-V<Subscript>2</Subscript>O<Subscript>5</Subscript>-MoO<Subscript>3</Subscript> System in the Solid State. The Crystal Structure of AlVO<Subscript>4</Subscript>

Phase relations in the ternary oxide system Al₂O₃-V₂O₅-MoO₃ in the solid state in air have been investigated by using the x-ray diffraction (XRD) and differential thermal analysis/thermogravimetric (DTA/TG) methods. It was confirmed that in the subsolidus area of the Al₂O₃-V₂O₅-MoO₃ system, there exist seven phases, that is Al₂O₃, V₂O_5(s.s.), MoO₃, AlVO₄, Al₂(MoO₄)₃, AlVMoO₇, and V₉Mo₆O₄₀. Seven fields, in which particular phases coexist at equilibrium, were isolated. The crystal structure of AlVO₄ has been refined from x-ray powder diffraction data. Its space group is triclinic, , Z = 6, with a = 0.65323(1) nm, b = 0.77498(2) nm, c = 0.91233(3) nm, α = 96.175(2)°, β = 107.234(3)°, γ = 101.404(3)°, V = 0.42555 nm³. The crystal structure of the compound is isotypic with FeVO₄. Infrared (IR) spectra of AlVO₄ and FeVO₄ are compared.