Structure Of Main Phase Research Articles

Fabrication of a Li4SiO4–Pb tritium breeding material

PbO2-doped Li4SiO4 pebbles were successfully fabricated by a liquid-atmosphere sintering process. Those pebbles sintered at 1000°C under atmospheric conditions were found to have an average diameter of 1.05mm, a sphericity of 98%, a theoretical density of 90.9%, an average crush load of 24.3N, and a main phase structure of Li4SiO4 with a small percentage of Li8PbO6. Subsequent optimization of this fabrication process yielded ceramic pebbles suitable for tritium breeding in a test blanket module (TBM).

Effect of the partial substitution of samarium for lanthanum on the structure and electrochemical properties of La15Fe77B8-type hydrogen storage alloys

La15Fe77B8 hydrogen storage alloys were prepared using a vacuum induction-quenching furnace. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) suggested that La15−xSmxFe2Ni76Mn5B2 (x=0, 2, 4, 6) alloys had multiphase structure including the main LaNi5 phase, La3Ni13B2 phase and (Fe, Ni) phase. With the increasing substitution of Sm for La, the main phase structure of alloys did not change, while the unit cell volumes decreased, the cycle stability was improved and the maximum discharge capacity decreased, but the low temperature maximum discharge capacity of the same substitution alloy was gradually approaching the maximum discharge capacity at room temperature, which showed that La15Fe77B8 hydrogen storage alloys of the partial substitution of Sm for La had better low-temperature dischargeability (LTD). For the same substitution alloys, self-discharge characteristics and cycle stability at low temperature were better than that at room temperature. Furthermore, the high-rate dischargeability (HRD) and the exchange current density I0 first increased and then decreased with the increasing of Sm content, whereas the hydrogen diffusion coefficient D in alloy bulk decreased gradually, which indicated that appropriate substitution of Sm for La improved the electrochemical kinetics properties of the alloys. The HRD was mainly dominated by the charge-transfer rate on the alloy surface.

Investigation of Structural and Electrical Properties of B-Site Complex Ion (Mg1/3Nb2/3)4+-Modified High-Curie-Temperature BiFeO3-BaTiO3 Ceramics

B-site complex ion (Mg1/3Nb2/3)-modified high-temperature ceramics 0.71BiFeO3-0.29BaTi1−x(Mg1/3Nb2/3)xO3 (BF-BTMNx) have been fabricated by the conventional solid-state reaction method. The compositional dependence of the␣phase structure, electrical properties, and depolarization temperature of the ceramics was studied. The main phase structure of BF-BTMNx ceramics is perovskite phase with pseudocubic symmetry. The experimental results show that the dielectric and piezoelectric properties, and temperature stability strongly depend on the (Mg1/3Nb2/3)4+ content. The optimum (Mg1/3Nb2/3) content enhances the piezoelectric properties, Curie temperature, and depolarization temperature. The ceramic with x = 1% exhibited enhanced electrical properties of d33 = 158 pC/N and kp = 0.322, combined with high-temperature stability with Curie temperature of Tc = 453°C and depolarization temperature of Td = 400°C. These results show that the ceramic with x = 1% is a promising lead-free high-temperature piezoelectric material.

Structure and Oxidation Behavior of Gradient Zr/ZrN/Zr Diffusion Barrier on the Ni-Based Superalloy by Arc Ion Plating

Gradient Zr/ZrN/Zr layer was deposited as a diffusion barrier between the NiCrAlYSi The overlay coating and Ni-base superalloy DZ125 by arc ion plating(AIP). The microstructure and high-temperature oxidation behavior of the diffusion barrier were studied. The results show that the gradient diffusion barrier is homogeneous and compact, and has strong bond strength with the substrate. The diffusion barrier is composed of three layers, among which the inner and outer layers are rich in Zr, and the middle layer is rich in ZrN. The main phase structure of the diffusion barrier is ZrN(200). During high temperature oxidation at 1100°C, the Zr/ZrN/Zr/HY3 compound coating system presents excellent oxidation resistance.

パルスレーザー堆積法による Cr-Cu-N-O 薄膜の作製

Chromium copper oxynitride (Cr-Cu-N-O) thin films have been successfully prepared through the pulsed laser deposition (PLD) method. The copper content in metallic elements (x) ranging from 0.0 to 0.4 were controlled by changing the surface area ratio of Cu target (SR) from 0 to 50%. The X-ray diffraction (XRD) revealed the crystal structure of main phase in all thin films to be NaCl (B1) type. The metallic copper phase exists in the thin films up to x=0.16, whereas diffraction peaks attributed to Cu were not observed in the thin film with x=0.06. From the result of SEM observation, columnar structure were observed in the thin film with x=0.0, 0.6, but the thin films up to x=0.16 shows globular structure. The Cr-Cu-N-O thin film with x=0.06 exhibited the highest Vickers hardness (HV) of 3900.

A study on structure and electrochemical properties of (La, Ce, Pr, Nd)2MgNi9 hydrogen storage electrode alloys

Abstract (La, Ce, Pr, Nd) 2 MgNi 9 hydrogen storage alloys were prepared through induction melting followed by a long annealing treatment. The structure and electrochemical properties of annealed alloys have been investigated by orthogonal design experiments. Both the individual effects of each substituting element and their interaction in alloys were studied systemically. It has been shown that the structure of main phase in alloys belongs to PuNi 3 -type with a space group R -3 m . Substituting rare-earth elements have a significant effect on both the phase structure of alloys and microstructure. The anisotropic change in the crystal structure of alloys can cause the acceleration of pulverization of alloy particles and result in the deterioration of the cyclic stability of alloy electrodes. Misch metals can raise the plateau pressure of hydrogen absorption/desorption. The discharge capacity of alloy ranges from 342.97 to 380.68 mAh g −1 depending on the sort and content of substituting elements. Both cerium and neodymium can obviously reduce the discharge capacity of alloy electrodes. When compared to the La 2 MgNi 9 alloy electrode, mish metals can significantly improve the high rate dischargeability of alloy electrodes. The improvement of the kinetic characteristic of alloy electrodes mainly results from the increase of the hydrogen diffusion rate in alloy bulk.

Hardness Optimization of (Cr,Mg)(N,O) Thin Films Prepared by Pulsed Laser Deposition

Chromium magnesium oxynitride ((Cr,Mg)(N,O)) thin films have been prepared by pulsed laser deposition (PLD) method with changing the surface area ratio of Mg target (SR) from 0 to 100 %. As a result of the analysis by energy dispersive X-ray spectroscopy (EDX), it was found that magnesium content in the total metallic elements (Cr1-x, Mgx) are controlled by changing SR from 0 to 100 % to be the x ranging from 0 to 1.0. Since the crystal structure of main phase in all thin films was found to be NaCl type, the XRD results showed that the thin films were mainly consisted of (Cr,Mg)(N,O). The hardness of (Cr,Mg)(N,O) thin films were increased almost linearly up to SR = 50 %, above which it decreases rapidly. The maximum Vickers hardness (HV) of 3600 was obtained for the thin film which was prepared by SR = 50 %, and the minimum HV of 1650 was obtained for the thin film which was prepared by SR = 100 %.

Effect of the Sm content on the structure and electrochemical properties of La 1.3 − xSm xCaMg 0.7Ni 9 ( x = 0–0.3) hydrogen storage alloys

La 1.3 − x Sm x CaMg 0.7Ni 9 ( x = 0–0.3) hydrogen storage alloys were prepared by inductive melting and the effect of the Sm content on the structure and electrochemical properties was investigated in the paper. The Sm substitution for La in La 1.3 − x Sm x CaMg 0.7Ni 9 ( x = 0–0.3) alloys does not change the main phase structure (the rhombohedral PuNi 3-type structure), but leads to a shrinkage of unit cell and a decrease of hydrogen storage capacity. With the increase of the Sm content in the alloys, the maximum discharge capacity of electrode decreases from 400.2 ( x = 0) to 346.6 mAh g −1 ( x = 0.3), but the high-rate dischargeability and cycling stability is improved. After 100 cycles, the capacity retention rate increases from 75 ( x = 0) to 85% ( x = 0.3).

A study on the structure and electrochemical properties of La 2Mg(Ni 0.95M 0.05) 9 (M = Co, Mn, Fe, Al, Cu, Sn) hydrogen storage electrode alloys

The effect of replacing part of the Ni by a metallic element in La 2MgNi 9 on the structure and electrochemical properties of the thus formed La 2Mg(Ni 0.95M 0.05) 9 quaternary alloys (M = Co, Mn, Fe, Al, Cu, Sn) was investigated. The substitutions did not change the main phase structure (the hexagonal PuNi 3-type structure), but all increased the unit cell volume of the alloys except the Sn substituted one, in which some LaNiSn second phase was formed. All hydrides of the alloys preserved the PuNi 3-type structure, while the amorphization of a portion of the hydride of the Al substituted alloy was observed. The substitution led to some decrease in hydrogen capacity, and an increase in hydride stability except for the Sn substituted one, and led to some decrease in both the discharge capacity and in the high-rate dischargeability (HRD), but led to a noticeable improvement in cycling stability for most of the substituted alloys (except for the Sn substituted one). The decrease of the high-rate dischargeability was due to the decrease of the electrocatalytic activity of the alloy electrodes and the lower diffusibility of hydrogen in the bulk of alloys as a result of the relatively low stability of the hydrides. The improvement in cycling stability was ascribed to the lower unit volume change on hydriding and the formation of a corrosion resistant layer on the alloy surface.

Structural and magnetic properties of Sm 2(Fe 1− xTi x) 17 ( x=0–0.1) alloys prepared by hydrogenation processes and their nitrides

Sm 2(Fe 1 − x Ti x ) 17 alloys ( x=0, 0.02, 0.04, 0.06, 0.08, 0.1) were prepared by arc-melting, subsequently annealing, hydrogenation and nitrogenation processes. The phase components, structures and magnetic properties involved in the processes have been investigated systematically. The Sm 2(Fe 1 − x Ti x ) 17 alloys have different main phases including Sm 2(Fe,Ti) 17 with Th 2Zn 17-type for x=0–0.04, Sm 3(Fe, Ti) 29 with Nd 3(Fe,Ti) 29-type for x=0.06, and Sm(Fe,Ti) 12 with ThMn 12-type for x=0.08–0.1. Curie temperature T c of the main phase of the alloys increases from 125°C for x=0 to 318°C for x=0.1. The corresponding hydride phases similar to the main phase structures of the parent alloys were formed after a hydrogen decrepitation (HD) process at 300°C. The hydrogenation at 800°C mainly shows a hydrogenation–disproportionation–desorption–recombination (HDDR) process. The HD and nitrogenation resulted in the Curie temperature increments of alloys by 30–150°C and by 140–350°C due to lattice expansions, respectively. The magnetic properties achieved for the Ti-containing alloys and their nitrides are lower than those of Sm 2Fe 17N δ prepared by the same processes of HD and HDDR.

HIGH-Tc SUPERCONDUCTIVITY AND STRUCTURE OF Y-Ba-Cu OXIDES REPLACED PARTIALLY BY La AND Li

The compounds with the composition Ba(Y1−xLax)(Cu1−yLiy)2On have been prepared in ceramic form. It has been discovered that this ceramic (x=0.33, y=0.10) exhibits high- Tc superconductivity with Tc (middle point) of 90K and T R=zero of 82K. By SEM analysis, it was shown that the main phase is some rectangle grains with size of 2−10μm. From X-ray powder diffraction, the structure of main phase, which belongs to orthorhombic crystal class with the lattice parameters of a=3.895Å, b=3.888Å, and c=11.598Å at room temperature, was determinated.

The structural history of the Lewisian rocks north-west of Loch Tollie, Ross-shire, Scotland

Synopsis In the Lewisian rocks north-west of Loch Tollie corresponding deformation during three successive phases of the Laxfordian orogeny is shown in meta-sediments, hornblende-schists, amphibolites and acid gneisses. Isoclinal folds, some drag folds and open folds and associated axial planar schistosity/foliation and mineral and intersection lineations were developed during the main phase of deformation. Asymmetrical folds, of which the Tollie anticline is the most prominent, refold the isoclinal folds and the associated main phase structures. Antiforms predominate, the synforms being largely represented by shear-belts. This mid phase deformation produced the dominant N.W.-S.E. trend of the lithological layers and the main phase foliation and the pattern of alternating belts of south-easterly and north-westerly plunging main phase lineation. After the emplacement of acidic veins and sheets, late phase deformation resulted in the development of steeply-plunging brittle folds and shear-belts with pseudo-tachylite.