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.

Structural changes induced by cation ordering in ferrotapiolite

2006 ◽  
Vol 70 (3) ◽  
pp. 319-328 ◽  
Author(s):  
M. Zema ◽  
S.C. Tarantino ◽  
A. Giorgiani
Keyword(s):  
Structural Changes ◽  
Rapid Determination ◽  
Linear Increase ◽  
X Ray Diffraction ◽  
Ionic Radii ◽  
Structural Modifications ◽  
Lattice Constants ◽  
Structure Factors ◽  
Polyhedral Volumes ◽  
Degree Of Order

AbstractStructural modifications as a function of the degree of order (Q) in FeTa2O6 ferrotapiolite have been characterized by means of single-crystal X-ray diffraction (SC-XRD). A total of 26 datasets covering the range of Q between 0.154 and 1 have been obtained by thermal treatments followed by quenching of natural tapiolite crystals. Ordering of Fe2+ at the A sites and of Ta5+ at the B sites causes a linear increase in the a/c lattice constants ratio, as a consequence of a linear decrease of the c dimension and only slight modifications of the a parameter. Calibration of a/c vs. Q represents a very useful tool for a rapid determination of the degree of order of tapiolite samples. Polyhedral volumes of the two octahedral sites vary linearly with Q as a consequence of the different ionic radii of the two species. Both the sites remain almost regular at all Q values but the B site shows an increasing off-centre displacement of the cation with increasing Q. Observed structure factors of supercell reflections, characterized by l ≠ 3n, increase linearly as a function of Q, thus representing a further tool for a quick evaluation of the degree of order.

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.

scholarly journals Interlamellar Space Configuration under Variable Environmental Conditions in the Case of Ni-Exchanged Montmorillonite: Quantitative XRD Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Marwa Ammar ◽  
Walid Oueslati ◽  
Nejmeddine Chorfi ◽  
Hafsia Ben Rhaiem
Keyword(s):  
Layer Structure ◽  
Theoretical Models ◽  
Xrd Analysis ◽  
Retention Mechanism ◽  
X Ray Diffraction ◽  
Host Materials ◽  
Space Organization ◽  
Interlamellar Space ◽  
Xrd Patterns ◽  
Low Charge

Interlamellar space organization of low-charge montmorillonite was studied by modeling of X-ray diffraction (XRD) patterns recorded under controlled relative humidity (RH) conditions on Ni saturated specimens. The quantitative XRD investigation, based on an indirect method consisting of the comparison of experimental00lreflections with the other calculated from structural models, is used to characterize eventual nanostructural changes alongc*axis of Ni-exchanged montmorillonite. This method allowed us to determine, respectively, the relative layer types contribution, the layer thickness, nanoconfiguration of the interlamellar space, and position, amount, and organization of water molecules and exchangeable cations. Obtained theoretical models exhibit heterogeneous hydration state which is the dominating character detected all over studied cycles. Along RH cycle a modification in the main structure of the host materials is performed and the presence of a mixed layer structure (MLS) is noted. The hydration hysteresis at the low and the high RH range can be explained by fluctuations in the water retention mechanism and hydration heterogeneities created within the smectite crystallite.

Synthesis and Optical Properties of Eu3+ Doped NaYF4 and KYF4 Micro/Nanocrystals

2016 ◽  
Vol 16 (4) ◽  
pp. 3857-3860 ◽  
Author(s):  
Siling Guo ◽  
Chunyan Cao ◽  
Renping Cao
Keyword(s):  
Optical Properties ◽  
Emission Spectra ◽  
Local Environment ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Two Samples ◽  
Xrd Patterns ◽  
The Eu

Through a hydrothermal method, 1 mol% Eu3+ doped NaYF4 and KYF4 micro/nanocrystals have been synthesized. The materials were characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM) images, room temperature photoluminescence (PL) excitation and emission spectra, and luminescent dynamic decay curves. The XRD analysis suggested the crystalline structures of the obtained samples. The FE-SEM images indicated the morphology and size of the obtained samples. The PL spectra illustrate the optical properties of Eu3+ in the two samples. Since it is sensitive to the local environment of the ion, the Eu3+ presents different optical properties in the NaYF4 and KYF4 materials.

The Fabrication of Refractory Cordierite from Aluminium Buff Mixture

2016 ◽  
Vol 690 ◽  
pp. 97-102
Author(s):  
Nuntaporn Kongkajun ◽  
Parinya Chakartnarodom ◽  
Warunee Borwornkiatkaew
Keyword(s):  
Microstructural Analysis ◽  
Secondary Phase ◽  
Xrd Analysis ◽  
Batch Composition ◽  
Brazilian Test ◽  
Raw Material ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Properties Of Materials

The aim of this work is to propose the utilization of aluminium buff from aluminium part manufacturer as a raw material for cordierite batch composition. The powder mixtures were compacted by uniaxial pressing. The green compacts were sintered at temperature in the range 1300-1400°C for 2 hours in air. The physical properties were characterized by Archimedes method, Brazilian test and dilatometry. Phase and microstructural analysis were done by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD analysis showed the major phase was cordierite along with sapphirine as a secondary phase. The fired properties of materials were demonstrated that the optimal properties was achieved from the specimen sintered at 1375 °C.

Investigation of Local Structure of ZnO with High Doping Copper Concentration (≥13 %mole) Prepared by Co-Precipitation Method

2021 ◽  
Vol 1028 ◽  
pp. 84-89
Author(s):  
Mohammad Syaiful Anwar ◽  
Kharisma Noor Afifah Supoyo ◽  
Retno Asih ◽  
Malik Anjelh Baqiya ◽  
Prae Chirawatkul ◽  
...  
Keyword(s):  
Local Structure ◽  
Parent Compound ◽  
Secondary Phase ◽  
Precipitation Method ◽  
Cu Doping ◽  
X Ray ◽  
Lattice Constants ◽  
Valence States ◽  
Xrd Patterns ◽  
Co Precipitation

Cu-doped ZnO (CZO) with Cu %mole of 0, 13, 14, and 15% have been synthesized by the co-precipitation method with controlled pH at 9. The diffraction pattern of CZO shows that a single phase of ZnO with wurtzite structure (w-ZnO) was achieved in the parent compound. In contrast, small fractions of the secondary phase of CuO monoclinic (m-CuO) were identified in the doped compounds. Rietveld-refinement on the X-Ray Diffraction (XRD) patterns reveals that the crystallite size of CZO is estimated in the range of 84 - 148 nm with instrumental correction factor and that CZO14 exhibits the most considerable fraction of m-CuO among the samples. Interestingly, lattice constants decrease by Cu doping. The effects of Cu doping on the valence state and the local structure were investigated by X-Ray Absorption Spectroscopy (XAS). Based on our analysis on both Cu K-edge and Zn K-edge XANES spectra, oxidation states of Cu and Zn ions are about +2 with no evidence of other valence states. Cu atom is likely to incorporate into wurtzite crystal lattice by occupying Zn sites in a small portion, and the doped compounds create a few oxygen vacancies.

scholarly journals Synthesis of novel red phosphate pigments from manganese carbonate to imitate natrophilite

Cerâmica ◽  
2018 ◽  
Vol 64 (372) ◽  
pp. 623-626
Author(s):  
H. Onoda ◽  
S. Fujikado
Keyword(s):  
Color Space ◽  
Xrd Analysis ◽  
Manganese Carbonate ◽  
X Ray Diffraction ◽  
Manganese Phosphate ◽  
A Value ◽  
Higher Temperature ◽  
Phosphate Pigments ◽  
Xrd Patterns ◽  
Visible Reflectance

Abstract A novel red pigment, sodium manganese phosphate (NaMnPO4), imitating natrophilite, was synthesized from manganese carbonate by heating under various conditions. The powders obtained were investigated by X-ray diffraction (XRD) analysis, infrared spectroscopy, ultraviolet-visible reflectance spectroscopy, and L*a*b* color space. Samples synthesized at 500-800 °C presented XRD patterns associated with NaMnPO4. By heating at a higher temperature, the samples exhibited lighter color. The sample synthesized at 700 °C indicated the highest a* value. Furthermore, the effects of varying relative amounts of constituents were also studied. The temperature and period of heating, volume of water, and phosphate content affected the color phase of the pigments.

Influence of Citric Acid on the Formation of Hydroxyapatite Powders by Using Ca(NO3)2-P2O5 Ethanol Solution System

2010 ◽  
Vol 152-153 ◽  
pp. 1248-1252
Author(s):  
Qing Chang ◽  
Hong Qiang Ru ◽  
Liang Yu ◽  
Ji Guang Li
Keyword(s):  
Particle Size ◽  
Citric Acid ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Transformation Process ◽  
Ethanol Solution ◽  
X Ray Diffraction ◽  
Solution System ◽  
Ca Addition ◽  
Xrd Patterns

In this study, nano-hydroxyapatite (HA) powders were synthesized via a simple sol-gel method using Ca(NO3)2•4H2O and P2O5 as starting materials. Two different precursors, with and without citric acid (CA), were prepared. The transformation process of HA from precursors, purity and particle size of the obtained HA powders were evaluated. HA derived from the precursor with CA showed a different transformation process from that without CA. It was observed that the content of CaO as an unavoidable major impurity was reduced due to the addition of CA. In the calcined powders from the CA-free precursor, X-ray diffraction (XRD) patterns revealed an intense CaO peak. For the calcined powders from the CA-addition precursor, XRD analysis showed a very weak CaO peak. It was also found that the synthesized HA powders from precursor with CA were finer than those without CA. The mechanism of the influence of CA on the formation, purity and particle size distribution of HA powders was discussed.

LOWER TEMPERATURE FORMATION OF ALUMINA THIN FILMS THROUGH SOL–GEL ROUTE

2008 ◽  
Vol 15 (05) ◽  
pp. 681-688 ◽  
Author(s):  
S. RIAZ ◽  
S. SHAMAILA ◽  
B. KHAN ◽  
S. NASEEM
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Structural Changes ◽  
Sol Gel ◽  
Stable Form ◽  
X Ray Diffraction ◽  
Glass Substrates ◽  
Lower Temperature ◽  
Xrd Patterns ◽  
Scanning Electron

Bayerite sol is spun onto single crystal Si substrate, after synthesis and optimization, to obtain films of thickness ~ 0.2 μm. The deposited films are room temperature dried and then heated up to a temperature of 350°C in order to obtain Al 2 O 3. Surface and structural changes, during heating, are observed with optical microscopy. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) are used for post-treatment analyses/characterization. The as-deposited and heated samples' surfaces are smooth as seen with optical and scanning electron microscope in case of optimized conditions. XRD patterns show the change from amorphous to crystalline behavior of these films when heated under various conditions. The most stable form of aluminum oxide, i.e. α- Al 2 O 3, is obtained when samples are heated up to a temperature of as low as 350°C. The thin films are also deposited onto sodalime glass substrates in order to confirm Al 2 O 3 formation through band gap probing. Photoconduction is used to find the energy band gap, which comes out to be 4.7 eV; lower value is correlated to the defect induced states in the band gap.

Phase Transition and Thermochromism of the Hybrid (C12H25NH3)2FeCl4

2006 ◽  
Vol 111 ◽  
pp. 55-58
Author(s):  
L.L. Guo ◽  
Y.D. Dai ◽  
H.X. Liu ◽  
Shi Xi Ouyang
Keyword(s):  
Phase Transition ◽  
Structural Changes ◽  
Energy Transition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Thermal Gravimetry ◽  
Reversible Phase Transition ◽  
Rotational Motions ◽  
Xrd Patterns ◽  
Reversible Phase

This paper focuses on the structural change and the thermochromism of the phase transition of the hybrid (C12H25NH3)2FeCl4. The temperature and the structures of the phase transition is investigated by a thermal gravimetry (TG) and differential scanning calorimetry (DSC), an infrared spectra (IR) and X-ray diffraction (XRD) patterns. The UV adsorption spectra account for the thermochromism. The results suggest that the reversible phase transition arises from the structural changes of the organic chains. The thermochromism is presumably due to the electrons redistribution on the levels and to the energy transition to translational and rotational motions of the organic chains.

Sign in / Sign up

Export Citation Format

Share Document