scholarly journals Texture of the Freshwater Shells from the Unionidae Family Collected in the Czech Republic Investigated by X-ray and Neutron Diffraction

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1483
Author(s):  
Monika Kučeráková ◽  
Jan Rohlíček ◽  
Stanislav Vratislav ◽  
Markéta Jarošová ◽  
Ladislav Kalvoda ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Shell Growth ◽  
Growth Direction ◽  
Mechanical Resistance ◽  
Minimal Amount ◽  
The Czech Republic ◽  
Crystallographic Preferred Orientation ◽  
X Ray ◽  
Engineering Sciences ◽  
Source Of Information

Bivalve shells exhibit extreme mechanical resistance despite using a minimal amount of material. The shells thus represent an inspiration and a source of information for environmental, geological, and engineering sciences. In this study, two species of freshwater shells from the Unionidae family, collected in the Czech Luznice River, were investigated with respect to their crystallographic preferred orientation by means of X-ray and neutron diffraction. The observed texture was found to be of a strongly uniaxial type, with the strength increasing along the shell growth direction. The c-axis of aragonite does not change during growth and its alignment remains perpendicular to the outer surface of the shell

Texture measurements in Al2O3 using BEKP

1994 ◽  
Vol 52 ◽  
pp. 608-609
Author(s):  
M. D. Vaudin ◽  
J. P. Cline
Keyword(s):  
Neutron Diffraction ◽  
Rapid Method ◽  
Crystallographic Orientation ◽  
Specimen Surface ◽  
X Ray Diffraction ◽  
Anisotropic Crystal ◽  
X Ray ◽  
Verification Method ◽  
Crystal Properties ◽  
Backscattered Electron

The study of preferred crystallographic orientation (texture) in ceramics is assuming greater importance as their anisotropic crystal properties are being used to advantage in an increasing number of applications. The quantification of texture by a reliable and rapid method is required. Analysis of backscattered electron Kikuchi patterns (BEKPs) can be used to provide the crystallographic orientation of as many grains as time and resources allow. The technique is relatively slow, particularly for noncubic materials, but the data are more accurate than any comparable technique when a sufficient number of grains are analyzed. Thus, BEKP is well-suited as a verification method for data obtained in faster ways, such as x-ray or neutron diffraction. We have compared texture data obtained using BEKP, x-ray diffraction and neutron diffraction. Alumina specimens displaying differing levels of axisymmetric (0001) texture normal to the specimen surface were investigated.BEKP patterns were obtained from about a hundred grains selected at random in each specimen.

Material Structure of Microcrystalline Silicon Deposited with an Expanding Thermal Plasma

2003 ◽  
Vol 762 ◽  
Author(s):  
C. Smit ◽  
D.L. Williamson ◽  
M.C.M. van de Sanden ◽  
R.A.C.M.M. van Swaaij
Keyword(s):  
Thermal Plasma ◽  
Hydrogen Plasma ◽  
Plasma Chemistry ◽  
Plasma Source ◽  
Growth Direction ◽  
Interaction Time ◽  
Material Structure ◽  
Average Particle ◽  
Microcrystalline Silicon ◽  
X Ray

AbstractExpanding thermal plasma CVD (ETP CVD) has been used to deposit thin microcrystalline silicon films. In this study we varied the position at which the silane is injected in the expanding hydrogen plasma: relatively far from the substrate and close to the plasma source, giving a long interaction time of the plasma with the silane, and close to the substrate, resulting in a short interaction time. The material structure is studied extensively. The crystalline fractions as obtained from Raman spectroscopy as well as from X-ray diffraction (XRD) vary from 0 to 67%. The average particle sizes vary from 6 to 17 nm as estimated from the (111) XRD peak using the Scherrer formula. Small angle X-ray scattering (SAXS) and flotation density measurements indicate void volume fractions of about 4 to 6%. When the samples are tilted the SAXS signal is lower than for the untilted case, indicating elongated objects parallel to the growth direction in the films. We show that the material properties are influenced by the position of silane injection in the reactor, indicating a change in the plasma chemistry.

scholarly journals Polymorphs of Rb3ScF6: X-ray and Neutron Diffraction, Solid-State NMR, and Density Functional Theory Calculations Study

2021 ◽  
Vol 60 (8) ◽  
pp. 6016-6026
Author(s):  
Aydar Rakhmatullin ◽  
Maxim S. Molokeev ◽  
Graham King ◽  
Ilya B. Polovov ◽  
Konstantin V. Maksimtsev ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Neutron Diffraction ◽  
Solid State Nmr ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
X Ray

scholarly journals Complex magnetic properties associated with competing local and itinerant magnetism in $${\text {Pr}}_2 {\text {Co}}_{0.86} {\text {Si}}_{2.88}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mily Kundu ◽  
Santanu Pakhira ◽  
Renu Choudhary ◽  
Durga Paudyal ◽  
N. Lakshminarasimhan ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Neutron Diffraction ◽  
Single Phase ◽  
Magnetic Transition ◽  
Muon Spin Rotation ◽  
Antiferromagnetic Coupling ◽  
Diffraction Measurement ◽  
Zero Field ◽  
Crystalline Electric Field ◽  
X Ray

AbstractTernary intermetallic compound $${\text {Pr}}_2 {\text {Co}}_{0.86} {\text {Si}}_{2.88}$$ Pr 2 Co 0.86 Si 2.88 has been synthesized in single phase and characterized by x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX) analysis, magnetization, heat capacity, neutron diffraction and muon spin rotation/relaxation ($$\mu$$ μ SR) measurements. The polycrystalline compound was synthesized in single phase by introducing necessary vacancies in Co/Si sites. Magnetic, heat capacity, and zero-field neutron diffraction studies reveal that the system undergoes magnetic transition below $$\sim$$ ∼ 4 K. Neutron diffraction measurement further reveals that the magnetic ordering is antiferromagnetic in nature with an weak ordered moment. The high temperature magnetic phase has been attributed to glassy in nature consisting of ferromagnetic clusters of itinerant (3d) Co moments as evident by the development of internal field in zero-field $$\mu$$ μ SR below 50 K. The density-functional theory (DFT) calculations suggest that the low temperature magnetic transition is associated with antiferromagnetic coupling between Pr 4f and Co 3d spins. Pr moments show spin fluctuation along with unconventional orbital moment quenching due to crystal field. The evolution of the symmetry and the crystalline electric field environment of Pr-ions are also studied and compared theoretically between the elemental Pr and when it is coupled with other elements such as Co. The localized moment of Pr 4f and itinerant moment of Co 3d compete with each other below $$\sim$$ ∼ 20 K resulting in an unusual temperature dependence of magnetic coercivity in the system.

scholarly journals X-ray diffraction analysis of kaolin M1 and M2 via the Williamson–Hall and Warren–Averbach methods

2021 ◽  
pp. 174751982098472
Author(s):  
Lalmi Khier ◽  
Lakel Abdelghani ◽  
Belahssen Okba ◽  
Djamel Maouche ◽  
Lakel Said
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Low Temperature ◽  
Diffraction Analysis ◽  
Mechanical Resistance ◽  
X Ray Diffraction ◽  
Integral Breadth ◽  
X Ray ◽  
Mullite Phase

Kaolin M1 and M2 studied by X-ray diffraction focus on the mullite phase, which is the main phase present in both products. The Williamson–Hall and Warren–Averbach methods for determining the crystallite size and microstrains of integral breadth β are calculated by the FullProf program. The integral breadth ( β) is a mixture resulting from the microstrains and size effect, so this should be taken into account during the calculation. The Williamson–Hall chart determines whether the sample is affected by grain size or microstrain. It appears very clearly that the principal phase of the various sintered kaolins, mullite, is free from internal microstrains. It is the case of the mixtures fritted at low temperature (1200 °C) during 1 h and also the case of the mixtures of the type chamotte cooks with 1350 °C during very long times (several weeks). This result is very significant as it gives an element of explanation to a very significant quality of mullite: its mechanical resistance during uses at high temperature remains.

Design of a novel Peltier-based cooling device and its use in neutron diffraction data collection of perdeuterated yeast pyrophosphatase

2010 ◽  
Vol 43 (5) ◽  
pp. 1113-1120 ◽  
Author(s):  
Esko Oksanen ◽  
François Dauvergne ◽  
Adrian Goldman ◽  
Monika Budayova-Spano
Keyword(s):  
Data Collection ◽  
Neutron Diffraction ◽  
Diffraction Data ◽  
Catalytic Mechanism ◽  
Inorganic Pyrophosphatase ◽  
Neutron Diffraction Data ◽  
Cooling Device ◽  
Data Set ◽  
X Ray ◽  
X Ray Crystallography

H atoms play a central role in enzymatic mechanisms, but H-atom positions cannot generally be determined by X-ray crystallography. Neutron crystallography, on the other hand, can be used to determine H-atom positions but it is experimentally very challenging. Yeast inorganic pyrophosphatase (PPase) is an essential enzyme that has been studied extensively by X-ray crystallography, yet the details of the catalytic mechanism remain incompletely understood. The temperature instability of PPase crystals has in the past prevented the collection of a neutron diffraction data set. This paper reports how the crystal growth has been optimized in temperature-controlled conditions. To stabilize the crystals during neutron data collection a Peltier cooling device that minimizes the temperature gradient along the capillary has been developed. This device allowed the collection of a full neutron diffraction data set.

An X-ray and Neutron Scattering Study of the Structure of Zinc Vanadate Glasses

2001 ◽  
Vol 56 (6-7) ◽  
pp. 478-488
Author(s):  
Uwe Hoppe ◽  
Rainer Kranold ◽  
Emil Gattef ◽  
Jörg Neuefeind ◽  
David A. Keen
Keyword(s):  
Neutron Diffraction ◽  
Coordination Number ◽  
Short Range ◽  
Short Range Order ◽  
X Ray ◽  
Coordination Numbers ◽  
Gaussian Functions ◽  
Scattering Study ◽  
Neutron Scattering Study ◽  
Vanadate Glasses

Abstract The short-range order of vitreous V20 5 and of three (Zn0)Jt(V20 5)1_x glasses with x = 0.2, 0.4, and 0.5 is studied by X-ray and neutron diffraction experiments where the change of the contrast allows to resolve the V -0 and Z n -0 correlations. The V -0 and the Z n -0 first-neighbor peaks are approximat­ ed by several Gaussian functions. In case of vitreous V20 5 two obvious V -0 distances exist which are related with V 0 4 and V 0 5 units. With ZnO additions the V -O coordination number decreases from 4.4 in vitreous V20 5 to 4.0 in the metavanadate glass where the strongest decrease of the fraction of V 0 5 units is found for glasses of * < 0.2. Dominantly, the V 0 5 groups are linked with the neighboring units by comers. The Z n-0 coordination numbers of the modified glasses are about five with closest dis­ tances of = 0.200 nm.

X-ray and neutron diffraction study of the defect crystal structure of the as-grown nonstoichiometric phase Y0.715Ca0.285F2.715

2013 ◽  
Vol 58 (4) ◽  
pp. 575-585 ◽  
Author(s):  
N. B. Bolotina ◽  
A. I. Kalyukanov ◽  
T. S. Chernaya ◽  
I. A. Verin ◽  
I. I. Buchinskaya ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Diffraction Study ◽  
Neutron Diffraction Study ◽  
Nonstoichiometric Phase ◽  
X Ray ◽  
Defect Crystal
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