scholarly journals Refinement of the Congruently Melting Composition of Nonstoichiometric Fluorite Crystals Ca1−xYxF2+x (x = 0.01–0.14)

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 696
Author(s):  
Denis N. Karimov ◽  
Elena A. Sulyanova ◽  
Boris P. Sobolev
Keyword(s):  
Linear Equation ◽  
Concentration Dependence ◽  
Lattice Parameters ◽  
Directional Crystallization ◽  
Congruently Melting ◽  
Melting Curves ◽  
Concentration Series

The concentration series of nonstoichiometric crystals Ca1–xYxF2+x (x = 0.01–0.14) was obtained from a melt by directional crystallization to refine the composition of the temperature maximum on the melting curves. A precision (±9 × 10−5 Å) determination of lattice parameters of theCa1–xYxF2+x crystals with the structure of fluorite (sp. gr. Fm-3m) was performed, and a linear equation of their concentration dependence was calculated: a(x) = 5.46385(5) + 0.1999(4) x. The distribution of yttrium along the crystals Ca1–xYxF2+x, the content of which is determined by the precision lattice parameters, is studied. The congruently melting composition x = 0.105(5) of the Ca1–xYxF2+x phase is refined by the method of directional crystallization.

Direct determination of the concentration dependence of diffusivities using combined model-based Raman and NMR experiments

2009 ◽  
Vol 277 (2) ◽  
pp. 96-106 ◽  
Author(s):  
E. Kriesten ◽  
M.A. Voda ◽  
A. Bardow ◽  
V. Göke ◽  
F. Casanova ◽  
...  
Keyword(s):  
Concentration Dependence ◽  
Direct Determination ◽  
Combined Model ◽  
Model Based

Unit cell constants of zeolites stabilized by dealumination determination of Al content from lattice parameters

1984 ◽  
Vol 19 (1) ◽  
pp. K1-K3 ◽  
Author(s):  
H. Fichtner-Schmittler ◽  
U. Lohse ◽  
G. Engelhardt ◽  
V. Patzelová
Keyword(s):  
Unit Cell ◽  
Lattice Parameters ◽  
Al Content

Novel Determination of Anti-Hypertensive Combination; Benidipine Hydrochloride and Nebivolol Hydrochloride by High Performance Chromatographic Method

2021 ◽  
pp. 5433-5438
Author(s):  
V.L.N. Balaji Gupta Tiruveedhi ◽  
Venkateswara Rao Battula ◽  
Kishore Babu Bonige ◽  
Tejeswarudu B.
Keyword(s):  
High Performance ◽  
Degradation Products ◽  
Research Work ◽  
Hplc Method ◽  
Assay Method ◽  
Injection Quantity ◽  
Relative Standard ◽  
Nebivolol Hydrochloride ◽  
Concentration Series

This research work was designed to establish and validate a novel stability indicating RP-HPLC method for the combined determination of Benidipine hydrochloride (BHE) and Nebivolol hydrochloride (NHE) in bulk and tablets, dependent on ICH guidelines.The assay method to analyse BHE and NHE was optimized with isocratic elution using acetonitrile: 0.1M acetate buffer (45:55, pH 5.1), Lichrospher ODS RP-18 column and flow pace of 1 ml/min. Total time for single run was 14 min. The injection quantity was 20μl, and was detected at 249nm. The method was verified on a concentration series of 1.25-10μg/ml (NHE) and 1.0-10μg/ml (BHE) for precision, accuracy and linearity. The LOD values were 0.059µg/ml and 0.028µg/ml for NHE and BHE, respectively. The LOQ values were 0.196µg/ml for NHE and 0.094µg/ml for BHE. The recovery percentages were 98.60-100.11% (BHE) and 98.94-101.50% (NHE) with relative standard deviation 0.250-0.694% (BHE) and 0.183-0.400% (NHE). The method was also observed to be efficient, and was sufficiently specific to measure BHE and NHE in the presence of stress-produced degradation products.

scholarly journals Magnetically Oriented Powder Crystal to Indexing and Structure Determination

2014 ◽  
Vol 70 (a1) ◽  
pp. C1560-C1560
Author(s):  
Fumiko Kimura ◽  
Wataru Oshima ◽  
Hiroko Matsumoto ◽  
Hidehiro Uekusa ◽  
Kazuaki Aburaya ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Crystal Lattice ◽  
Powder Diffraction ◽  
Diffraction Method ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Lattice Parameters

In pharmaceutical sciences, the crystal structure is of primary importance because it influences drug efficacy. Due to difficulties of growing a large single crystal suitable for the single crystal X-ray diffraction analysis, powder diffraction method is widely used. In powder method, two-dimensional diffraction information is projected onto one dimension, which impairs the accuracy of the resulting crystal structure. To overcome this problem, we recently proposed a novel method of fabricating a magnetically oriented microcrystal array (MOMA), a composite in which microcrystals are aligned three-dimensionally in a polymer matrix. The X-ray diffraction of the MOMA is equivalent to that of the corresponding large single crystal, enabling the determination of the crystal lattice parameters and crystal structure of the embedded microcrytals.[1-3] Because we make use of the diamagnetic anisotropy of crystal, those crystals that exhibit small magnetic anisotropy do not take sufficient three-dimensional alignment. However, even for these crystals that only align uniaxially, the determination of the crystal lattice parameters can be easily made compared with the determination by powder diffraction pattern. Once these parameters are determined, crystal structure can be determined by X-ray powder diffraction method. In this paper, we demonstrate possibility of the MOMA method to assist the structure analysis through X-ray powder and single crystal diffraction methods. We applied the MOMA method to various microcrystalline powders including L-alanine, 1,3,5-triphenyl benzene, and cellobiose. The obtained MOMAs exhibited well-resolved diffraction spots, and we succeeded in determination of the crystal lattice parameters and crystal structure analysis.

Sign in / Sign up

Export Citation Format

Share Document