X-ray Diffraction and Vibrational Spectroscopic Study of the Influence of Cis- and Trans-Unsaturation on the α-Phase of Triacylglycerols

The infrared spectra and powder X-ray diffraction patterns of polycrystalline YPO4-YCrO4 samples are studied from the point of view of their crystal symmetry. Mixed crystals of the D4h19 symmetry are formed over the region of 0-30 mol.% YPO4 in YCrO4. The Td → D2d → D2 or C2v(GS eff) correlation is appropriate for both PO43- and CrO43- anions.

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Mechanical Alloying Behavior in the Nb-Si, Ta-Si, and Nb-Ta-Si Systems

MRS Proceedings ◽

10.1557/proc-133-415 ◽

1988 ◽

Vol 133 ◽

Cited By ~ 3

Author(s):

K. S. Kumar ◽

S. K. Mannan

Keyword(s):

High Temperature ◽

Mechanical Alloying ◽

Mechanical Milling ◽

Room Temperature ◽

Crystalline Compound ◽

X Ray Diffraction ◽

X Ray ◽

Β Phase ◽

Α Phase

ABSTRACTThe mechanical alloying behavior of elemental powders in the Nb-Si, Ta-Si, and Nb-Ta-Si systems was examined via X-ray diffraction. The line compounds NbSi2 and TaSi2 form as crystalline compounds rather than amorphous products, but Nb5Si3 and Ta5Si3, although chemically analogous, respond very differently to mechanical milling. The Ta5Si3 composition goes directly from elemental powders to an amorphous product, whereas Nb5Si3 forms as a crystalline compound. The Nb5Si3 compound consists of both the tetragonal room-temperature α phase (c/a = 1.8) and the tetragonal high-temperature β phase (c/a = 0.5). Substituting increasing amounts of Ta for Nb in Nb5Si3 initially stabilizes the α-Nb5Si3 structure preferentially, and subsequently inhibits the formation of a crystalline compound.

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An x‐ray diffraction study of lattice imperfections in cold‐worked fcc alloys: II. Copper‐gallium (α phase)

Journal of Applied Physics ◽

10.1063/1.323858 ◽

1977 ◽

Vol 48 (4) ◽

pp. 1442-1448 ◽

Cited By ~ 25

Author(s):

S. K. Chatterjee ◽

S. K. Halder ◽

S. P. Sen Gupta

Keyword(s):

Diffraction Study ◽

X Ray Diffraction ◽

X Ray ◽

Α Phase ◽

Fcc Alloys ◽

Cold Worked

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Microstructural and Corrosion Studies by Immersion in 3.5% NaCl Solution on Aged Mg-9Al-1Zn-XCa Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.969.93 ◽

2019 ◽

Vol 969 ◽

pp. 93-97

Author(s):

S. Manivannan ◽

B. Narenthiran ◽

A. Sivanantham ◽

S.P. Kumaresh Babu

Keyword(s):

Corrosion Behaviour ◽

Nacl Solution ◽

X Ray Diffraction ◽

Corrosion Attack ◽

X Ray ◽

Α Phase ◽

Corrosion Studies ◽

Different Temperatures ◽

Xrd Techniques ◽

Scanning Electron

The experimatal alloys were aged at different temperatures of 180°C, 200°C, 220°C, and 240º C with calcium addition levels of (X=0.5, 1, 1.5, 2%) on Mg-6Al-1Zn-XCa alloy were investigated in 3.5% NaCl solution. All the experimatal alloys were immersed in 3.5% NaCl solutions and the resulted surface were analyzed to study the corrosion behaviour and its surface topography by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersed spectroscopy (EDS) and X-ray diffraction (XRD) techniques. The result shows that corrosion attack occurred predominantly on ß phase and α phase exhibit relatively minor corrosion. In addition to that the increased aging temperature coarsens the intermetallic as well as α- Mg grains, which shows adverse effect to corrosion resistances and the best result were obtained at composition of 0.5wt.% Ca aged at 200°C.

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Hierarchical structure of the triclinic α-phase crystal in nylon 6,12 mediated by two-dimensional confinement

Journal of Applied Crystallography ◽

10.1107/s1600576719014705 ◽

2020 ◽

Vol 53 (1) ◽

pp. 27-33

Author(s):

Ziwei Lai ◽

Shuailin Zhang ◽

Nan Zheng ◽

Shichen Yu ◽

Masaki Ageishi ◽

...

Keyword(s):

Hierarchical Structure ◽

Phase Cell ◽

X Ray Diffraction ◽

X Ray ◽

Hierarchical Nanostructure ◽

Α Phase ◽

Triclinic Symmetry ◽

Phase Crystal ◽

Unit Cells ◽

The Impact

It has been recognized that macromolecular chains can self-assemble into a hierarchical structure from lamellae to spherulites in bulk crystallization. However, little account has been taken of crystal symmetry effects on the hierarchical nanostructure in polymers under cylindrical confinement. In this research, a model polymer, nylon 6,12, most commonly occurring in the triclinic α phase, was chosen in order to demonstrate the effect of triclinic symmetry on the 2D-constrained polymer nanostructure. The self-arranging unit of nylon 6,12 takes various forms, including stems, unit cells, hydrogen-bonded sheets, lamellae and complex spherulites, which is an essential structural feature for investigating hierarchical nanostructure. The rod nanostructure in confinement was examined by cross-checking electron and X-ray diffraction techniques. It is found that the a* axis of the α-phase cell is inclined at about ±6–11° to the rod long axis within the a*b* plane around the c axis (c axis ⊥ rod long axis). The rotation of the a*b* plane most likely results from the impact of the triclinic symmetry on the molecular chain packing under 2D confinement. A mechanism for this a*b* plane tilting is proposed.

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Synthesis of Polyazobenzenes Exhibiting Photoisomerization and Liquid Crystallinity

Polymers ◽

10.3390/polym11020348 ◽

2019 ◽

Vol 11 (2) ◽

pp. 348 ◽

Cited By ~ 2

Author(s):

Masashi Otaki ◽

Reiji Kumai ◽

Hajime Sagayama ◽

Hiromasa Goto

Keyword(s):

Conjugated Polymers ◽

Main Chain ◽

Cross Coupling ◽

Industrial Applications ◽

Optical Absorption Spectroscopy ◽

X Ray Diffraction ◽

Liquid Crystallinity ◽

X Ray ◽

Cis And Trans ◽

Chain Type

While only a few studies have investigated the synthesis of main chain-type polyazobenzenes, they continue to draw an increasing amount of attention owing to their industrial applications in holography, dyes, and functional adhesives. In this study, dibromoazobenzene was prepared as a monomer for constructing azo-based π-conjugated polymers. Miyaura–Suzuki cross-coupling polymerization was conducted to develop copolymers containing an azobenzene unit as a photoisomerization block and a pyrimidine-based liquid crystal generator block. The prepared polymers exhibited thermotropic liquid crystallinity and underwent cis and trans photoisomerization upon irradiation with ultraviolet and visible light. Furthermore, the photoisomerization behavior was examined using optical absorption spectroscopy and synchrotron X-ray diffraction spectrometry.

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