A Facile and Low-Cost Method to Produce Ultrapure 99.99999% Gallium

As one of the critical raw materials, very pure gallium is important for the semiconductor and photoelectric industry. Unfortunately, refining gallium to obtain a purity that exceeds 99.99999% is very difficult. In this paper, a new, facile and efficient continuous partial recrystallization method to prepare gallium of high purity is investigated. Impurity concentrations, segregation coefficients, and the purification effect were measured. The results indicated that the contaminating elements accumulated in the liquid phase along the crystal direction. The order of the removal ratio was Cu > Mg > Pb > Cr > Zn > Fe. This corresponded to the order of the experimentally obtained segregation coefficients for each impurity: Cu < Mg < Pb < Cr < Zn < Fe. The segregation coefficient of the impurities depended strongly on the crystallization rate. All observed impurity concentrations were substantially reduced, and the purity of the gallium obtained after our refinement exceeded 99.99999%.

Orientations – perfectly colored

The inverse pole figure (IPF) coloring for a suitable evaluation of crystal orientation data is discussed. The major goal is a high correlation between encoding color and crystal orientation. Revised color distributions of the fundamental sectors are introduced which have the advantages of (1) being applicable for all point groups, (2) not causing color discontinuities within grains, (3) featuring carefully balanced regions for red, cyan, blue, magenta, green and yellow, and (4) an enlarged gray center in opposition to a tiny white center. A new set of IPF color keys is proposed which is the result of a thorough analysis of the colorization problem. The discussion considers several topics: (a) the majority of presently applied IPF color keys generate color discontinuities for specifically oriented grains; (b) if a unique correlation between crystal direction and color is requested, discontinuity-preventing keys are possible for all point groups, except for {\overline 4}, {\overline 3} and {\overline 1}; (c) for a specific symmetry group several IPF color keys are available, visualizing different features of a microstructure; and (d) for higher symmetries a simultaneous IPF mapping of two or three standard reference directions is insufficient for an unequivocal orientation assignment. All color keys are available in MTEX, a freely available MATLAB toolbox.

EBSD study of the morphology and orientation of the primary and eutectic phases in Al–Cu alloys during solidification under a strong magnetic field

The effect of a strong magnetic field on the morphology and orientation of the Al2Cu dendrite and Al–Al2Cu eutectic in Al–Cu alloys was studied using electron backscatter diffraction (EBSD) technology. The experimental results revealed that the applied magnetic field modified the morphology and orientation of both the Al2Cu dendrite and the Al–Al2Cu eutectic significantly. The magnetic field caused a break in the Al2Cu dendrite and the degeneration of Al–Al2Cu eutectic lamellae during directional solidification. It was also found that the magnetic field caused the formation of dislocations in the α-Al and Al2Cu phases during directional solidification. In addition, the primary and eutectic Al2Cu phases were oriented with the 〈001〉 crystal direction along the magnetic field during volume solidification. Both α-Al and Al2Cu phases were oriented with the 〈001〉 crystal direction along the solidification direction during directional solidification under an axial magnetic field. The above phenomena were enhanced as the magnetic field increased; this could be attributed to magnetic crystalline anisotropy of the material and thermoelectric magnetic effects. This study may offer experimental evidence that shows that thermoelectric magnetic effects significantly influence dendrite arrays during directional solidification in a magnetic field.

Strong-Gravity Experiments on Perovskite-Type Oxides

Strong gravitational field causes the displacement or/and sedimentation of atoms in solids, by which we can changes the crystalline state or/and composition in multicomponent condensed matter. Perovskite-type doped manganite, La1-xSrxMnO3(LSMO) has unique magnetoresistance effect which is called “colossal magnetoresistance (CMR)”. In this study, the strong gravity experiment (0.40x106G, 400°C, 20h) was performed on the LSMO oriented crystal to examine the change in composition or structure. The LSMO crystal whose growing crystal direction is normal to (214) plane was prepared by the floating zone method. The EPMA and XRD results of the gravity sample revealed that the La compositions decrease in the crystal grain, while the structure did not change much. The SQUID analysis showed that the magnetic property of the gravity sample had changed.

Crystal structure of [propane-1,3-diylbis(piperidine-4,1-diyl)]bis[(pyridin-4-yl)methanone]–4,4′-oxydibenzoic acid (1/1)

In the title co-crystal, C25H32N4O2·C14H10O5, molecules are connected into supramolecular chains aligned along [102] by O—H...N hydrogen bonding. These aggregate into supramolecular layers oriented parallel to (20-1) by C—H...O interactions. These layers then stack in anABABpattern along theccrystal direction to give the full three-dimensional crystal structure. The central chain in the dipyridylamide has ananti–anticonformation. The dihedral angle between the aromatic ring planes is 29.96 (3)°. Disorder is noted in some of the residues in the structure and this is manifested in two coplanar dispositions of one statistically disordered carboxylic acid group.