SUPERCONDUCTING PROPERTIES OF Y1-xTbxBa2Cu3O7-δ AND Y1-xTbxSr2Cu2.7Mo0.3O7-δ

2010 ◽  
Vol 24 (04n05) ◽  
pp. 419-429 ◽  
Author(s):  
S. MIRSHAMSI ◽  
S. FALLAHI ◽  
M. AKHAVAN
Keyword(s):  
Secondary Phase ◽  
Rietveld Analysis ◽  
Creep Model ◽  
Structural Parameter ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Metallic Behavior ◽  
Thermally Activated ◽  
Diffraction Patterns ◽  
Xrd Patterns

We have investigated the effect of Tb substitution for Y in both YBa 2 Cu 3 O 7-δ and the more stabilized YSr 2 Cu 2.7 Mo 0.3 O 7-δ systems. Adding Mo has been shown to stabilize the Tb -doped systems. The samples of Y 1-x Tb x Ba 2 Cu 3 O 7-δ with x=0.0, 0.1, 0.15, 0.2, 0.3, 0.35, 0.4, 0.5, 0.55, and 0.6, and of Y 1-x Tb x Sr 2 Cu 2.7 Mo 0.3 O 7-δ with x=0.0, 0.2, 0.4, 0.6, and 0.8 have been prepared by the standard solid-state reaction technique. The superconducting transition occurs only with x=0–0.5 for the Ba -based samples, and with x=0–0.8 for the Sr -based samples. The structural parameter identification and phase determination of the samples have been carried out by the Rietveld analysis of the X-ray diffraction patterns, which indicates that Tb does not enter in the structure of the Ba -based 123 phase, while in the Sr -based 123 structure Tb enters in the structure and substitutes for Y . In the Y 1-x Tb x Ba 2 Cu 3 O 7-δ samples, a new secondary TbBaO 3 phase forms; and by increasing the amount of Tb , the secondary phase increases as the Y 123 phase decreases. But, for the Y 1-x Tb x Sr 2 Cu 2.7 Mo 0.3 O 7-δ samples, by increasing the amount of Tb doping, no impurity phase is detected in the XRD patterns. For both groups of samples, by increasing the amount of Tb , the normal resistivity increases, and the metallic behavior of the resistivity changes to semiconducting behavior. The magnetoresistance of Y 1-x Tb x Ba 2 Cu 3 O 7-δ was measured in different magnetic fields. The width of transition for the same values of magnetic field increases with the increase of Tb doping, indicating that with the increase of Tb , grains link weaker due to the increase in the amount of the secondary TbBaO 3 phase. The pinning energy has also been evaluated based on the thermally activated phase creep model.

scholarly journals Polymorphism of tricalcium silicate in Portland cement: A fast visual identification of structure and superstructure

2003 ◽  
Vol 18 (1) ◽  
pp. 7-15 ◽  
Author(s):  
M. Courtial ◽  
M.-N. de Noirfontaine ◽  
F. Dunstetter ◽  
G. Gasecki ◽  
M. Signes-Frehel
Keyword(s):  
Portland Cement ◽  
Structural Model ◽  
Rietveld Analysis ◽  
Tricalcium Silicate ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Diffraction Patterns ◽  
Xrd Patterns ◽  
Industrial Compounds ◽  
Open Question

So-called alite is a solid solution of tricalcium silicate Ca3SiO5 with a few percent of impurities. It constitutes the major phase of anhydrous Portland cement. In industrial compounds, alite crystallizes into two monoclinic forms designated M1 and M3. The possibility of correlation between the crystallographic structure of the clinker and its reactivity is still an open question. The answer of such a question involves a proper quantitative analysis of the various phases—including the exact alite polymorph—of the industrial product. The rather similar structure of the two alites makes it difficult to distinguish them from their XRD patterns. This paper shows that five angular windows in the X-ray diffraction patterns can be used with synthetic alites as well as industrial compounds, to identify the nature of the actual polymorph (M1 or M3) present and the structural model to be used (with or without superstructure) in subsequent Rietveld analysis of the data.

Analysis of Selected Area Diffraction Patterns With Winjade

1998 ◽  
Vol 4 (S2) ◽  
pp. 342-343 ◽  
Author(s):  
S. D. Walck ◽  
P. Ruzakowski-Athey
Keyword(s):  
Single Phase ◽  
Xrd Analysis ◽  
Analysis Program ◽  
X Ray Diffraction ◽  
Program Module ◽  
Vast Number ◽  
One Dimensional ◽  
X Ray ◽  
Diffraction Patterns ◽  
Xrd Patterns

The analysis of Selected Area Diffraction (SAD) patterns that are collected from a single phase material having sufficient crystallites to provide continuous rings is relatively straightforward. However, when this condition is not met and there may be several phases present having rings of a spotty nature, the pattern is complex and can be quite difficult to analyze manually because of the vast number of discrete spots. WinJade from MDI is an X-ray diffraction (XRD) analysis program with an Electron Diffraction Program Module (EDPM) that can be used to aid in the analysis of SAD patterns. The EDPM produces Integrated Circular Density Plots (ICDP), which are one-dimensional intensity profiles plotted as a function of equivalent XRD 20 values or crystal d-spacings. These ICDP's can be overlayed with XRD patterns or with reference lines from the NIST and JCPDS crystalline databases for direct comparisons.

Fabrication of PbO-Type Structure β-FeSe Superconductor Ceramics by Solid State Reaction Method

2013 ◽  
Vol 790 ◽  
pp. 21-24
Author(s):  
Yun Yi Wu ◽  
Jian Gao ◽  
Tao Li ◽  
Zhi Qiang Hua
Keyword(s):  
Solid State ◽  
High Vacuum ◽  
Secondary Phase ◽  
Vacuum State ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Solid State Sinter ◽  
Metallic Behavior ◽  
X Ray ◽  
Sinter Method

PbO-type structure β-FeSe superconductor ceramic were successfully prepared by solid state sinter method in high vacuum state. The structures of the ceramics were investigated by X-ray diffraction and scanning electron microscopy. X-ray diffraction indicates that the sample prepared by two-steps method exhibited a much improved crystallinity. And as sintering temperature increases to 700°C, secondary phase Fe7Se8 phase peak disappear and α-Fe peak weakened. Besides, the ceramic prepared in 700°C exhibited a denser surface morphology in comparison to that prepared in 410°C and its composition is closer to the chemical formula FeSe according to EDX compositional analyses. It was noted that the resistivity of the sample, sintered at 700°C using two-steps sinter method, shows a linear metallic behavior from room temperature and onset is around T = 7.5 K.

EFFECT OF GAMMA IRRADIATION ON YBa2Cu3O7-δ HIGH TEMPERATURE SUPERCONDUCTORS

2008 ◽  
Vol 22 (27) ◽  
pp. 2699-2707 ◽  
Author(s):  
SAADAT A. SIDDIQI ◽  
RABIA SIDDIQUI ◽  
SALAMAT ALI
Keyword(s):  
Gamma Irradiation ◽  
Structural Changes ◽  
High Temperature Superconductors ◽  
Secondary Phase ◽  
Xrd Analysis ◽  
Theoretical Explanation ◽  
X Ray Diffraction ◽  
Lattice Constants ◽  
Xrd Patterns ◽  
Experimental Findings

Samples of YBa 2 Cu 3 O 7-δ superconducting ceramic were prepared and characterized by resistivity measurements using the four probe method and structural analysis using X-ray diffraction (XRD). XRD-patterns show the presence of orthorhombic Y -123 phase with a small fraction of secondary phase, YBa 2 Cu 3 O 5. Samples were irradiated with gamma (γ) rays using Co 60 source with five successive doses of 2.5 Mrad. A monotonic increase in the Tc0 value was observed for radiation dosage up to 10 Mrad. When exposed to even higher γ-doses, the Tc0 value leveled off at a saturation value or decreased. XRD-analysis shows slightly changed values of the lattice constants and a mild shift of diffraction peaks towards a lower 2θ value. These observations indicate structural changes in YBa 2 Cu 3 O 7-δ induced upon gamma irradiation. The present work describes our experimental findings and attempts to offer a theoretical explanation for the effects observed.

X-ray powder diffraction analysis of the heteropoly-molybdate (MoO2)0.5PMo14O42

2003 ◽  
Vol 18 (3) ◽  
pp. 236-239 ◽  
Author(s):  
L. Marosi ◽  
J. Cifré ◽  
C. Otero Areán
Keyword(s):  
Catalytic Activity ◽  
Diffraction Analysis ◽  
Computer Modeling ◽  
Powder Diffraction ◽  
Rietveld Analysis ◽  
Nitrogen Atmosphere ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

The new heteropoly blue compound (MoO2)0.5PMo14O42, which is relevant in the context of catalytic activity of heteropoly-molybdates, was prepared by controlled thermolysis of (NH4)3PMo12O40 at 730 K in a nitrogen atmosphere. Powder X-ray diffraction analysis showed that this compound has a cubic unit cell, space group Pn3m (No. 224), with ao=11.795(2) Å, Z=2 and DXR=4.2466 g cm−3. Computer modeling and Rietveld analysis of powder diffraction patterns led to a proposed structure of the corresponding Keggin-cage unit PMo14O42.

An X-ray diffraction system with controlled relative humidity and temperature

1996 ◽  
Vol 11 (4) ◽  
pp. 288-289 ◽  
Author(s):  
H. Hashizume ◽  
S. Shimomura ◽  
H. Yamada ◽  
T. Fujita ◽  
H. Nakazawa ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Room Temperature ◽  
Control Unit ◽  
Saturated Water Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Saturated Water ◽  
Sample Chamber ◽  
Diffraction Patterns ◽  
Xrd Patterns

A system enabling X-ray diffraction patterns under controlled conditions of relative humidity and temperature has been devised and combined with an X-ray powder diffractometer. Relative humidity in the sample space is controlled by mixing dry N2 gas with saturated water vapor. Temperatures of the sample and inner wall of the sample chamber are monitored by two attached thermocouples and the information was fed back to the control unit. Relative humidity between 0% and the 95%, and temperature between room temperature and 60 °C can be controlled. All parameters including those for XRD are programmable and the system runs automatically. The function of the system was checked by recording the XRD patterns of montmorillonite (a clay mineral) and NaCl under increasing and decreasing relative humidity.

Nano-Sized Zirconium Carbides: Synthesis, Characterisation and Irradiation

2005 ◽  
Vol 908 ◽  
Author(s):  
Mickaël Dollé ◽  
Dominique Gosset ◽  
Christine Bogicevic ◽  
Guido Baldinozzi ◽  
Fabienne Karolak ◽  
...  
Keyword(s):  
Diffraction Method ◽  
Grazing Incidence ◽  
Rietveld Analysis ◽  
Metal Carbides ◽  
X Ray Diffraction ◽  
Waste Production ◽  
Nuclear Plants ◽  
Volume Swelling ◽  
Diffraction Patterns ◽  
New Generation

AbstractThe projects of a new generation of nuclear plants with improved yield and drastical reduction of waste production make necessary the development of materials able to withstand high temperature (1000-1200°C) in normal conditions. New materials such as the refractory transition metal carbides are then considered. These materials have a ceramic-like, brittle behaviour. Their mechanical properties might be improved by decreasing the particles size at a nanometer level. The behaviour under irradiation of such nano-sized materials have then to be compared with classical micro-sized ones. High density, nano-sized materials have been obtained by two different sintering techniques. In order to simulate neutron irradiation, the samples were irradiated with low energy heavy ions. Consequently, the damaged material has a low thickness (100-200 nm), requiring surface analysis methods. Here, the grazing incidence X-ray diffraction method is used. From a Rietveld analysis of the diffraction patterns, the micro-sized materials show a linear volume swelling in the range 20-40 dpa in the Zr sublattice. Nano- and micro-sized materials both show high internal distortions.

New complete assignment of X-ray powder diffraction patterns in graphitic carbon nitride using discrete Fourier transform and direct experimental evidence

2017 ◽  
Vol 19 (38) ◽  
pp. 26072-26084 ◽  
Author(s):  
Bo-wen Sun ◽  
Hong-yu Yu ◽  
Yong-jing Yang ◽  
Hui-jun Li ◽  
Cheng-yu Zhai ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Experimental Evidence ◽  
Powder Diffraction ◽  
Carbon Nitride ◽  
Graphitic Carbon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Complete Assignment ◽  
Diffraction Patterns ◽  
Xrd Patterns

To date, there have been only a few studies focusing on the assignment of X-ray diffraction (XRD) patterns in graphitic carbon nitrides (g-C3N4) and contradictory determination for a broad peak around 12°–14° has been perplexing.

An expert system for the structural characterization of kaolinites

Clay Minerals ◽  
1990 ◽  
Vol 25 (3) ◽  
pp. 249-260 ◽  
Author(s):  
A. Plançon ◽  
C. Zacharie
Keyword(s):  
Expert System ◽  
Defect Structure ◽  
Defect Structures ◽  
X Ray Diffraction ◽  
Diffraction Profile ◽  
X Ray ◽  
Diffraction Patterns ◽  
Xrd Patterns

AbstractUntil recently, the determination of the defect structures (previously referred to incorrectly as “crystallinity”) of kaolinites has been obtained in one of two ways: (1) measurement of the Hinckley index, or (2) by comparing calculated X-ray diffraction patterns based on a model of the defect structure (including types of defects and abundances) with experimental diffraction profiles. The Hinckley method is simple and easy to perform but contains no real information about the defect structure. Calculated XRD patterns are based on real defects but these calculations are time consuming and require some skill in application. Another approach is proposed: an expert system which will accurately describe the defect structure of kaolinites based on a few measurements taken from a normal powder diffraction profile. This system has been verified for nine kaolinite samples for which the defect structure was previously determined by comparison of calculated and observed diffraction profiles. The expert system reproduced the correct defect structure for each of the samples.

A study of the electrochemical synthesis of ZnO thin films

1997 ◽  
Vol 75 (11) ◽  
pp. 1439-1444 ◽  
Author(s):  
Z.H. Gu ◽  
T.Z. Fahidy ◽  
R. Hornsey ◽  
A. Nathan
Keyword(s):  
Zinc Oxide ◽  
Nitrate Solution ◽  
Zinc Nitrate ◽  
X Ray Diffraction ◽  
Zinc Nitrate Solution ◽  
Principal Characteristics ◽  
X Ray ◽  
Oxide Cathode ◽  
Diffraction Patterns ◽  
Xrd Patterns

The principal characteristics of the cathode deposition of zinc oxide from slightly acidified aqueous zinc nitrate solution at 65 °C were studied via potentiodynamic electrolysis, potentiostatic electrolysis, and X-ray diffraction patterns. The results indicate the reliability of a low-temperature electrolytic path of synthesis, and avenues of further exploration. Keywords: zinc oxide, cathode deposition, XRD patterns, FBM theory.

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