scholarly journals Oscillatory Changes in Structural Characteristics in Multicomponent Ceramics, YBCO

2022 ◽  
Author(s):  
B. Kodess
Keyword(s):  
Phase Composition ◽  
Crystal Lattice ◽  
Structural Characteristics ◽  
Oscillatory Behavior ◽  
Unit Cell Dimension ◽  
Unit Cell ◽  
Specific Process ◽  
X Ray ◽  
Compression And Expansion ◽  
Long Time

Abstract. The structural characteristics of samples of a four-component superconducting material (YBCO) after exposure to X-ray irradiation during a long time are investigated. The effect of X-ray beam processing on angular positions (corresponding parameters of the crystal lattice) and the width of Bragg reflections is established. The phenomenon of oscillatory behavior in the unit cell dimension with long-time irradiation is found. The analysis of the profiles of reflection also demonstrates the presence of reversible changes phase composition with the exposure time. The observed phenomena reflect the presence of a nontrivial and specific process of compression and expansion of the unit cell due to the accumulation and then disengagement outside of ionized oxygen, which is formed under such irradiation exposure on the surface of the samples.

scholarly journals Impact of Machining and Phase Composition Change of Titanium Alloyed with Molybdenum

2022 ◽  
Author(s):  
B. Kodess
Keyword(s):  
Phase Composition ◽  
Single Crystal ◽  
High Precision ◽  
Orthorhombic Phase ◽  
Unit Cell Dimension ◽  
Unit Cell ◽  
Cell Dimension ◽  
Composition Change ◽  
X Ray

Abstract. The titanium samples alloyed with molybdenum and aluminum are used to conduct full high-precision X-ray experiments enabling to determine the characteristic of the atomic interrelations - the unit cell dimension, and to establish the phase components of the doped single crystal. An orthorhombic phase is found, the volume of which increases after the deformation impact.

Composition-dependent magnitude of atomic shuffles in Ti–Nb martensites

2014 ◽  
Vol 47 (4) ◽  
pp. 1374-1379 ◽  
Author(s):  
Matthias Bönisch ◽  
Mariana Calin ◽  
Lars Giebeler ◽  
Arne Helth ◽  
Annett Gebert ◽  
...  
Keyword(s):  
Experimental Data ◽  
Chemical Composition ◽  
Diffraction Data ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Orthorhombic Unit Cell ◽  
Homogenization Treatment ◽  
X Ray

In this work the structural characteristics of martensitic phases in the Ti–Nb system are studied in detail. While the distortion of the orthorhombic unit cell of α′′-martensite by the addition of β-stabilizing atoms is well documented in the literature, comprehensive experimental data on the detailed atomic positions and how they vary with chemical composition are missing. For this study, a series of binary Ti–Nb alloys were prepared by casting techniques, followed by homogenization treatment and water quenching. Rietveld-based analyses of X-ray diffraction data were used to study the gradual structural changes of α′- and α′′-martensites effected by the addition of Nb, and their compositional boundaries were determined. In the case of orthorhombic α′′, it was established that, besides the lattice parameters, the positions of the atoms on the (002)α′′planes respond very sensitively to the amount of Nb present.

scholarly journals Long Time Stability Investigation for Structural and Magnetic Properties of Ti-doped Barium Ferrite

2019 ◽  
Vol 3 (2) ◽  
pp. 53-57
Author(s):  
Mohammed Abdul Malek Al Saadi
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Barium Hexaferrite ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Storage Process ◽  
X Ray ◽  
Air Atmosphere ◽  
Long Time

Barium hexaferrite (BHF) (BaFe12O19) and its substituted derivatives have been considered as the most potential magnetic candidates with considerable chemical stability and physiochemical characteristics. BHF with x ferrite ions substituted by titanium (Ti-doped BTHF) (BaTixFe12-xO19) (x=1 and x=3) was prepared from ferric oxide (Fe2O3), barium oxide (BaO), and titanium oxide (TiO2) of purity >98%. The materials were mixed with deionized water and then dried at 1100°C and 1200°C overnight. For the formation of BaFe12O19 phase, the mixture was annealed at a rate of 10°C/min in static air atmosphere until reaching 1200°C and then maintained for 10 h. Structural properties of these samples were measured using X-ray diffraction (XRD) and scanning electron microscopy, while magnetic properties were measured using vibrating sample magnetometer (VSM) device. Magnetic and structural characteristics are investigated after preserving Ti-doped BHF samples at room temperature and ambient conditions for 12 years. The samples are characterized using the same previous techniques to find out the possible effect of long period storage on their properties. The results showed that the storage process has little effect on these properties where the granular size increased due to increased oxidation. XRD tests also showed the absence of Ti at low ratios due to increased oxidation of ferrite. VSM results showed increased magnetic properties after storage due to increased iron oxide.

scholarly journals Unravelling the impact of Ta doping on the electronic and structural properties of titania: A combined theoretical and experimental approach

2021 ◽  
Author(s):  
Vignesh Kumaravel ◽  
Maria Barbara Maccioni ◽  
Snehamol Mathew ◽  
Steven Hinder ◽  
John Bartlett ◽  
...  
Keyword(s):  
Crystal Lattice ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Structural Characteristics ◽  
Energy Levels ◽  
Average Crystallite Size ◽  
Defect States ◽  
X Ray ◽  
The Impact ◽  
Ta Doping

The introduction of new energy levels in the forbidden band through the doping of metal ions is an effective strategy to improve the thermal stability of TiO2. In the present study, the impact of Ta doping on the anatase to rutile transition (ART), structural characteristics, anion and cation vacancy formation were investigated in detail using Density Functional Theory (DFT) and experimental characterisation including, X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS). The average crystallite size of TiO2 decreases with an increase in the Ta concentration. At high temperatures, more oxygen atoms entered the crystal lattice and occupy the vacancies, leading to lattice expansion. Importantly, we find that Ta doping preserved the anatase content of TiO2 up to annealing temperatures of 850 °C which allows anatase stability to be maintained at typical ceramic processing temperatures. The substitution of Ti4+ by the Ta5+ ions increased the electron concentration in the crystal lattice through formation of Ti3+ defect states. Raman studies revealed the formation of new Ta bonds via disturbing the Ti-O-Ti bonds in the crystal lattice. It is concluded that under the oxidising conditions, Ta5+ ions could be enhanced on Ta-TiO2 surface due to the slow diffusion kinetics.

Synchrotron X-ray powder diffraction data of atorvastatin

2008 ◽  
Vol 23 (4) ◽  
pp. 350-355 ◽  
Author(s):  
Selma Gutierrez Antonio ◽  
Fernanda Ribeiro Benini ◽  
Fabio Furlan Ferreira ◽  
Paulo César Pires Rosa ◽  
Carlos de Oliveira Paiva-Santos
Keyword(s):  
Synchrotron Radiation ◽  
Powder Diffraction ◽  
High Throughput ◽  
Diffraction Data ◽  
Unit Cell Dimension ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters

X-ray powder diffraction data collected in transmission and high-throughput geometries were used to analyze form I of atorvastatin. The X-ray wavelength of the synchrotron radiation used in this study was determined to be λ=1.3771 Å. Form I of atorvastatin was found to be triclinic with space group P1 and unit cell parameters a=5.4568(2) Å, b=9.8887(4) Å, c=30.3091(9) Å, α=76.801(3)°, β=99.177(5)°, γ=105.318(5)°, V=1527.1(1) Å3, Z=1, and M=1209.41 g mol−1 Alternatively, another unit cell dimension can be used to describe the same P1 crystal with a=5.4564(2) Å, b=9.8883(4) Å, c=29.6555(8) Å, α=95.745(3)°, β=94.297(5)°, γ=105.327(5)°, and V=1526.8(1) Å3.

Structural Study of the Disordered RECd6 Quasicrystal Approximants (RE = Tb, Ho, Er, Tm and Lu)

2006 ◽  
Vol 61 (6) ◽  
pp. 644-649 ◽  
Author(s):  
Shu Ying Piao ◽  
Cesar P. Gömez ◽  
Sven Lidin
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Structural Study ◽  
Diffraction Data ◽  
Unit Cell Dimension ◽  
Unit Cell ◽  
Cell Dimension ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Types

The crystal structures of approximants RECd6 (RE = Tb, Ho, Er, Tm and Lu) have been refined from single crystal X-ray diffraction data. This work is a continuation of a previous study of MCd6 approximants [1] in which the different types of disorder of the central Cd4 tetrahedra located in the dodecahedral cavities were examined. The structures of the title compounds are all similar to GdCd6 and disorder was observed in all these compounds. There is a correlation between the anisotropic displacement parameter and the unit cell dimension

scholarly journals The magnetic and optical properties of the benzene ring in aromatic compounds

1929 ◽  
Vol 126 (800) ◽  
pp. 143-154 ◽  
Keyword(s):  
Crystal Lattice ◽  
Benzene Ring ◽  
Unit Cell ◽  
Organic Crystals ◽  
Parallel Plates ◽  
X Ray ◽  
Suitable Material ◽  
Starting Point ◽  
Sufficient Precision ◽  
Complete Interpretation

The present paper describes the third of a series of investigations undertaken at the suggestion of Sir C. V. Raman of the remarkable magnetic and optical characters exhibited by organic crystals of the aromatic class. In the earlier papers the author had described the optical and the magnetic characters of naphthalene crystals and also of anthracene and other organic compounds and discussed the significance of the results. In all these cases, however, the fact that there were two or more molecules per unit cell in the crystal lattice, and that the X-ray results available did not fix with sufficient precision either the form of the molecules or their orientation relatively to each other and to the crystal lattice prevented a complete interpretation of the results. Mrs. Lonsdale’s recent admirable investigation of the structure of hexamethylbenzene has made further and very significant progress possible. She has shown that this substance crystallises in the triclinic system with one molecule per unit cell and that the carbon atoms in the molecule form flat hexagonal rings parallel to a cleavage plane. Hence this substance forms a very suitable material for the experimental study of the magnetic and optical characters of the benzene ring in its substitution products. It has accordingly been used as the starting point in the present investigation. For convenience of reference Mrs. Lonsdale's results will be briefly recalled here. The nomenclature adopted is the same as hers. The substance crystallises out of benzene mostly in parallel plates with the be plane prominently developed. Often there are two other pairs of faces, fairly well developed, which were chosen by her as the ab and ac planes. The unit cell thus defined is a triclinic cell which was found to have the following axes and axial angles:— A. U. ° ˊ 9.010 . . . . . . . . . . . . . . . . . 44 27 8.926 . . . . . . . . . . . . . . . . . 116 43 5.344 . . . . . . . . . . . . . . . . . 119 34 The crystal is centrosymmentrical with one molecule per cell.

Characteristic of Crystallite Sizes and Lattice Deformations Changes in the Oxide Layer Formed on Steel Operated for a Long Time at an Elevated Temperature

2013 ◽  
Vol 203-204 ◽  
pp. 204-207 ◽  
Author(s):  
Monika Gwoździk
Keyword(s):  
Phase Composition ◽  
Elevated Temperature ◽  
Oxide Layer ◽  
Flue Gas ◽  
Phase Identification ◽  
X Ray ◽  
Term Operation ◽  
Long Time ◽  
Crystallite Sizes

The paper presents results of studies on the phase composition, crystallite sizes and lattice deformations of oxide layers formed during a long-term operation on X10CrMoVNb9-1 steel. Test specimens were taken from a live steam pipeline operated at 535°C for 70,000 hours. X-ray studies were carried out on the tube outside surface (on the flue gas side), then the layer’s surface was polished and the diffraction measurements repeated to reveal differences in the originated oxides layer. X-ray phase analysis was performed using a SEIFFERT 3003 T/T X-ray diffractometer, with a cobalt tube of λCo= 0.17902nm wavelength. crystallographic database were used for the phase identification.

scholarly journals Single Crystal X-ray Diffraction, Spectroscopic and Mass Spectrometric Studies of Furanocoumarin Peucedanin

2014 ◽  
Vol 9 (1) ◽  
pp. 1934578X1400900
Author(s):  
Magdalena Bartnik ◽  
Marta Arczewska ◽  
Anna A. Hoser ◽  
Tomasz Mroczek ◽  
Daniel M. Kamiński ◽  
...  
Keyword(s):  
Single Crystal ◽  
Crystal Lattice ◽  
2D Nmr ◽  
Unit Cell ◽  
Spectroscopic Techniques ◽  
Fragmentation Pattern ◽  
X Ray Diffraction ◽  
X Ray ◽  
Single Column ◽  
Biological Tests

The structure of peucedanin, isolated from Peucedanum tauricum Bieb. (Apiaceae), has been established using single crystal X-ray diffraction. This furanocoumarin isolated from the light petroleum extract of P. tauricum fruits was characterized by high resolution EI-MS, sATR-FTIR and 2D NMR spectroscopic techniques. The EI-MS showed the typical fragmentation pattern of methoxyfuranocoumarins. Extensive 1D (1H and 13C) as well as 2D NMR data enabled complete assignment of the carbon atoms in the peucedanin molecule. The FTIR data confirms intermolecular hydrogen bonding between peucedanin molecules in polar solvents. Peucedanin crystallises in the R-3 space group from the trigonal system with one molecule in the asymmetric part of the unit cell. The crystal lattice of peucedanin consists of the molecules arranged in separate columns. They are related by two fold screw axes and centres of symmetry. Interestingly, peucedanin columns form two channels per unit cell with a diameter of 7.5Å going through the crystal lattice in the Z-direction. These channels are filled with disordered water molecules, which are surrounded by hydrophobic methyl groups and are located exactly at the centres of the channels. The peucedanin molecules are stacked in a single column with the opposite orientation of the neighbouring molecules. These results could be interesting in further application of this molecule, for example in biological tests of its activity.

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