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Abstract: Ternary Ti–Nb–Zr alloys consisting of biocompatible alloying elements have been prepared to investigate the effect of Zr content on β→α phase transformation, microstructure and mechanical properties. The study showed that element Zr stablized the β phase and that its effect on β phase transus exhibited a “margin effect”. With increasing Zr content, the microstructure of the Ti–Nb–Zr alloy was refined and the strength of ternary Ti–Nb–Zr alloys was also improved while the plasity significantly decreased. The Ti72Nb25Zr3 alloy exhibited the maximum ultimate tensile strengh of 775MPa and Ti73Nb25Zr2 exhibited the lowest elastic modulus of 62GPa. The low elastic modulus of Ti73Nb25Zr2 was attributed to the formation of stress-induced martensite (α″ phase). [Copyright &y& Elsevier]

Abstract: X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize Nd x Gd2− x Zr2O7 (x =0, 0.6, 1.0, 1.4, and 2.0) solid solutions pressureless-sintered by using ceramic powders acquired by chemical-coprecipitation and calcination method. Heat capacity measurements were performed with a heat flux-type differential scanning calorimetry in the temperature range of 298.15–1050K. The heat capacity of Nd x Gd2− x Zr2O7 solid solutions increases with increasing the concentration x of neodymium cations from x =0 to x =2.0 at identical temperature levels. At 298.15K, the heat capacities of Nd0.6Gd1.4Zr2O7, NdGdZr2O7 and Nd1.4Gd0.6Zr2O7 are 217, 220 and 224JK−1 mol−1, respectively. Thermodynamic functions such as enthalpy increment, entropy and Gibbs energy functions were calculated from the measured heat capacity data. [Copyright &y& Elsevier]

Abstract: Structural evolution and thermophysical properties of (Sm x Gd1−x )2Zr2O7 (0≤ x ≤1.0) were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-temperature dilatometer and laser flash diffusivity measurements from room temperature to 1400°C. Pure Gd2Zr2O7 ceramics exhibit a defective fluorite-type structure, however, (Sm x Gd1−x )2Zr2O7 (0.1≤ x ≤1.0) ceramics are with a pyrochlore-type structure. The linear thermal expansion coefficients of (Sm x Gd1−x )2Zr2O7 ceramics increase with increasing test temperature. The thermal diffusivities of (Sm x Gd1−x )2Zr2O7 ceramics range from 0.390 to 0.770mm2 s−1, while the thermal conductivities of (Sm x Gd1−x )2Zr2O7 ceramics are located within the range of 1.20 to 1.99Wm−1 K−1 from room temperature to 1400°C. [Copyright &y& Elsevier]

(La 1− x Er x ) 2 Zr 2 O 7 ( x = 0, 0.025, 0.05, 0.075, 0.1) nanocrystals have been successfully prepared by the chemical co-precipitation and calcination method, and were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy. The nanocrystals calcined at 800 °C for 5 h exhibit good crystallinity and have a particle size of about 25 nm. The emission band centered at 528 nm is identified as the 2 H 11/2 → 4 I 15/2 transition, the emission bands centered at 550 nm and 562 nm are attributed to the 4 S 3/2 → 4 I 15/2 transition, and the emission bands centered at 663 nm and 682 nm are ascribed to the 4 F 9/2 → 4 I 15/2 transition. The emission intensity increases with increasing Er 3+ content, up to a critical concentration between x = 0.025 and x = 0.05, and then decreases with further increasing Er 3+ concentration. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the phase transformation and electrochemical characteristics of the as-cast and annealed La0.75Mg0.25Ni x (x= 3.0, 3.3, 3.5, 3.8) alloys were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), pressure composition isotherm (PCI) and electrochemical measurements. The as-cast alloys were composed of LaNi5, (La,Mg)2Ni7 and (La,Mg)Ni3 phases. Phase transformation of LaNi5 and (La,Mg)Ni3 phases into (La,Mg)2Ni7 phase occurred during annealing treatment, leading to the increase of the (La,Mg)2Ni7 phase and decrease or even depletion of the LaNi5 and (La,Mg)Ni3 phases. The two plateaus observed in P–C isotherms of the as-cast alloys tended to become single and the plateau pressure dropped after the phase transformation by annealing. Electrochemical study showed that for the alloy electrodes with and without annealing treatment, the maximum discharge capacity and HRD initially increased then decreased with x increasing from 3.0 to 3.8. The transformation of the LaNi5 and (La,Mg)Ni3 phases into (La,Mg)2Ni7 phase favored the maximum discharge capacity and cycling stability but suppressed the activation as well as HRD of the La0.75Mg0.25Ni x (x= 3.0, 3.3, 3.5, 3.8) alloy electrodes. The annealing treatment significantly improved the cycling stability of the alloy electrodes by alleviating the pulverization and oxidation degree of the electrode alloys. [Copyright &y& Elsevier]

Abstract: Nano SiC/BN(C) ceramic was prepared from the mechanically-alloyed amorphous SiBCN powder, hot pressed at 1900°C under 80MPa in the nitrogen atmosphere for 30min. The microstructures and the properties of the prepared ceramic were carefully studied by XRD, TEM (SAED, HRTEM and EFTEM), EELS and property testing. Results show that the ceramic consists of β-SiC, α-SiC and BN(C). SiC has an average grain size of about 78.2±32.4nm, most of which have numerous stacking faults. BN(C) has small size, no fixed shape and turbostratic structure with heterogeneously distributed t-carbon layers, t-BN layers and B-doped t-carbon layers. It has uniform distribution in the ceramic, retarding the atomic diffusion and being responsible for the fine grains. The ceramic has room-temperature density, flexural strength, Young’s modulus and fracture toughness of 2.6g/cm3, 331.1MPa, 139.4GPa and 2.8MPam1/2, respectively. The detailed investigation of the hot-pressed SiC/BN(C) ceramic is helpful for the further study of this material and other ceramics, targeted for the high-temperature applications. [Copyright &y& Elsevier]

Abstract: This paper concentrates on the influence of gadolinia on structure and thermal expansion property of ZrO2–4.5mol%Y2O3 (YSZ) ceramics. The YSZ–xGd2O3 (0≤ x ≤7.5 in mol%) ceramics were synthesized by solid state reaction method at 1500°C for 2h in air. The relative density, phase structure and thermal expansion property of YSZ–xGd2O3 ceramics were investigated by the Archimedes method, X-ray diffraction and high-temperature dilatometer. The thermal expansion coefficients of YSZ–xGd2O3 ceramics increase with the increase in temperature. The thermal expansion coefficients of YSZ–xGd2O3 ceramics first decrease with increasing the mole fraction (x) of gadolinia from x =0 (YSZ) to x =4.5 (YSZ–4.5Gd2O3), and then increase from x =4.5 (YSZ–4.5Gd2O3) to x =7.5 (YSZ–7.5Gd2O3) in the temperature range of 50–1200°C. The YSZ–4.5Gd2O3 ceramics have the lowest thermal expansion coefficient in YSZ–xGd2O3 ceramics, which is due to formation of the () ionic vacancy clustering. [Copyright &y& Elsevier]

Abstract: Ferroelectric Bi3.25La0.75Ti3O12 (BLT) nanotubes were synthesized by sol–gel technique using nanochannel porous anodic aluminum oxide (AAO) templates, and were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). BLT nanotubes with diameter of around 240nm and the wall thickness of about 25nm exhibited a single orthorhombic perovskite structure and highly preferential crystal growth along the [117] orientation, which have smooth wall morphologies and well-defined diameters corresponding to the diameter of the applied template. The formation mechanism of BLT nanotubes was discussed. [Copyright &y& Elsevier]

Abstract: A chemical co-precipitation method is proposed for the synthesis of nano-sized multiferroic BiFeO3 powders. Pure phase can be obtained by controlling the chemical co-precipitation process, pH level, Bi content, and calcination temperature. The evolutions of phase constitution and structural characteristic of BiFeO3 powders were investigated by XRD, FT-IR, SEM, and TEM techniques. The slight excess in Bi content plays an important role in the synthesis. The resultant BiFeO3 powders are of pure phase and have the R3c crystal structure under optimized conditions. The grain size of the BiFeO3 powders with weak magnetism ranges from 30–40nm. [ABSTRACT FROM AUTHOR]

Abstract: We report the synthesis of perovskite ferroelectric nanowire strontium bismuth tantalate (SrBi2Ta2O9, SBT). Sol–gel techniques have been used. The morphology and structures are analyzed via SEM, TEM and XRD. The XRD and TEM analysis show that the structure of SBT nanowires is single orthorhombic perovskite with A2 1 am structure space group. The obtained SBT nanowires with an average length of 35μm and a diameter of 200nm are c-axis preferred orientation in the templates. The formation mechanism of SBT nanowires with complex crystal structure was discussed. [ABSTRACT FROM AUTHOR]