The Application of Neutron Topography to the Study of X-ray Sensitive Organic Crystals - a Possible Alternative to X-ray Topography.

1989 ◽  
Vol 166 ◽  
Author(s):  
M. Dudley

ABSTRACTNeutron topography has been carried out on organic single crystals of varying Xray sensitivity, in order to test the feasibility of the technique as an alternative to X-ray topography for the study of the influence of defects on the solid state reactivity of X-ray sensitive single crystals. Specimens studied include the diacetylene PTS, and Pyrene. A comparison of the strain sensitivity and spatial resolution of the neutron and X-ray based techniques is made. Preliminary results of dynamic neutron topographic studies of the UV induced polymerization in PTS are presented. These results are compared to those obtained from similar X-ray topographic studies.Results indicate that the neutron technique can be a useful ally technique to the analogous X-ray techniques in studies of the influence of defects on reactivity in specimens of moderate X-ray sensitivity. In cases of extreme sensitivity, the neutron technique is the only one available for studies of this nature.

2018 ◽  
Vol 74 (7) ◽  
pp. 1006-1009 ◽  
Author(s):  
Matthias Weil

Single crystals of Ba2K2Te2O9(dibarium dipotassium nonaoxidoditellurate), (I), Ba2KNaTe2O9(dibarium potassium sodium nonaoxidoditellurate), (II), and Ba2CaTeO6(dibarium calcium hexaoxidotellurate), (III), were obtained from KNO3/KI or KNO3/NaNO3flux syntheses in platinum crucibles for (I) and (II), or porcelain crucibles for (III). (I) and (II) are isotypic and are members of triple perovskites with general formulaA2[12co]A′[12co]B2[6o]B′[6o]O9. They crystallize in the 6H-BaTiO3structure family in space-group typeP63/mmc, with theA,A′,BandB′ sites being occupied by K, Ba, Te and a second Ba in (I), and in (II) by mixed-occupied (Ba/K), Ba, Te and Na sites, respectively. (III) adopts theA2[12co]B′[6o]B′′[6o]O6double perovskite structure in space-group typeFm-3m, with Ba, Ca and Te located on theA,B′ andB′′sites, respectively. The current refinement of (III) is based on single-crystal X-ray data. It confirms the previous refinement from X-ray powder diffraction data [Fuet al.(2008).J. Solid State Chem.181, 2523–2529], but with higher precision.


1996 ◽  
Vol 51 (10) ◽  
pp. 1407-1410 ◽  
Author(s):  
B. Wedel ◽  
Hk. Müller-Buschbaum

Single crystals of Ba2Nb2TeO10) have been prepared by solid state reactions in air. X-ray investigations led to orthorhombic symmetry, space group D152h-Pbca, a = 7.242(4), b = 12.433(3), c = 9.932(3) Å. Z = 4. Nb5+ and Te6+ show octahedral coordination by O2- . The crystal structure is characterized by planes of edge- and corner-sharing NbO6- and TeO6octahedra. It is shown that in spite of nearly identical lattice constants of Ba2Nb2TeO10 with compounds of the composition M0,5BaNbTe2O9 the so far unknown crystals of these substances may not be derived from the Ba2Nb2TeO10 type.


1978 ◽  
Vol 33 (2) ◽  
pp. 146-148 ◽  
Author(s):  
Hk. Müller-Buschbaum ◽  
M. Harder

Single crystals of the compound Ba2Fe11Al11O34 were prepared by solid state reaction (1700 °C) of BaO-Fe2O3-Al2O3 mixtures. The crystal structure was investigated by X-ray data (space group D46h-P63/mmc, lattice constants: a = 565.3, c = 2281.0 pm). Ba2Fe11Al11O34 is isotypic with Na2O · 11 Al2O3, the structure of β-alumina


1981 ◽  
Vol 59 (1) ◽  
pp. 38-44 ◽  
Author(s):  
R. H. Marchessault ◽  
Suzanne Coulombe ◽  
Hiromichi Morikawa ◽  
Keizo Okamura ◽  
J. F. Revol

The solid state properties of poly-β-hydroxybutyrate (PHB) were investigated for samples with degrees of polymerization [Formula: see text] from 4 to 994. The observed melting points ranged from 47 °C to 180 °C. Electron diffractograms on carefully prepared single crystals of a high molecular weight sample provided data which confirmed the reported a and b parameters from X-ray fiber diffraction and provided clear justification for the P212121 space group. The observed intensities in the electron diffractogram, corresponding to (hk0) reflections, were compared with the predicted intensities for two proposed structures in the literature. The observed and calculated structure factors for both structures were in good agreement. Small angle X-ray diffraction of the meridional maximum for annealed "cold drawn" and "hot drawn" fibers showed a distinctly different dependence on temperature than the maximum for stacks of lamellar single crystals. For oligomers a long spacing was observed which was about twice the length of the sample [Formula: see text] multiplied by the crystalline advance per monomer.


2002 ◽  
Vol 55 (4) ◽  
pp. 271 ◽  
Author(s):  
N. B. Singh ◽  
A. Pathak ◽  
R. Fröhlich

Vapours of p-benzoquinone (BQ) have been found to react with solid 2,4,5-trichlorophenol (TCP). The reaction product (BQ-TCP) separated in the form of monoclinic single crystals, the structure of which was determined by X-ray diffraction to reveal that the two molecules are linked by a single hydrogen bond between the carbonyl oxygen of BQ and the phenolic hydrogen of TCP.


2021 ◽  
Author(s):  
Sivasubramani Vediyappan ◽  
Arumugam Raja ◽  
Ro Mu Jauhar ◽  
Ramachandran Kasthuri ◽  
Vishwanathan Vijayan ◽  
...  

Abstract 2-amino-5-nitropyridine 4-chlorobenzoic acid (1:1) (2A5NP4CBA), a potentially useful organic adduct compound has been synthesized and grown as optically transparent single crystals by conventional slow evaporation solution technique (SEST) for the first time in the literature. The formation of the new crystalline material was confirmed by the single-crystal X-ray diffraction (SXRD) analysis and the crystal structure of the grown crystal was found to be monoclinic. Fourier transform infrared (FTIR) spectrum has been recorded by the KBr pellet technique to determine the various vibrational functional groups in the title material. The powder X-ray diffraction (PXRD) and high-resolution X-ray diffraction (HRXRD) analyses have been carried out and the obtained results reveal that the grown crystal has a single-phase and is free from structural grain boundaries. The obtained less value (32 arc-s) of full width at half maximum (FWHM) for (001) plane indicates the excellent crystalline quality of the title 2A5NP4CBA single crystal. The linear optical properties were evaluated by the UV-vis-NIR absorption and transmittance analyses and the obtained results reveal that the grown crystal possesses more than 70% of optical transmittance window with the cut-off edge at 419 nm. The thermal analysis discloses that the grown crystal possesses good thermal stability of about 187°C. To determine the appropriateness of the grown crystal for the high-power laser application, laser damage threshold (LDT) analysis has been carried out by Nd: YAG laser of a wavelength of 1064 nm. The third-order nonlinear optical coefficients such as nonlinear absorption (β), nonlinear refraction (n 2 ) and nonlinear susceptibility (χ (3) ) have been evaluated by utilizing the single beam Z-scan technique using a solid-state laser of wavelength 532 nm. The calculated ꭓ (3) value is found to be reasonably good compared to other organic single crystals which are reported in the literature. The optical limiting (OL) behavior of the title crystal was evaluated using a solid-state laser at 532 nm and the limiting threshold was found to be 7.8 mW/cm 2 .


2010 ◽  
Vol 132 (33) ◽  
pp. 11398-11401 ◽  
Author(s):  
Panče Naumov ◽  
Petre Makreski ◽  
Gjorgji Petruševski ◽  
Tomče Runčevski ◽  
Gligor Jovanovski

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