FORMATION OF THE "2223" SUPERCONDUCTING PHASE IN Bi4−xPbxSr3Ca3Cu4O16 SUPERCONDUCTORS

1990 ◽  
Vol 04 (10) ◽  
pp. 673-680
Author(s):  
I. M. TANG ◽  
K. EAIPRASERTSAK ◽  
R. CHITAREE
Keyword(s):  
High Temperature ◽  
Volume Fraction ◽  
Superconducting Phase ◽  
Temperature Decrease ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Temperature Component ◽  
Multiphase Systems ◽  
Temperature Component ◽  
Diffraction Patterns

Formation of the "2223" superconducting phase in Pb doped Bi 4 Sr 3 Ca 3 Cu 4 O 16 superconductor is studied. The X-ray diffraction patterns of the Bi 4−x Pb x Sr 3 Ca 3 Cu 4 O 16 (0.7 < x < 1.2) superconductors formed by various heat treatments indicate that they are all multiphase systems containing both the high T c and low T c superconductors, with the volume fraction of the "2223" phase increasing with increased Pb content. The high temperature component have extrapolated T c 's of around 105 K. The zero resistivity temperature decrease with lead content but are well above the reported T c (75 K) of the Pb free host superconductor.

An In Situ High-Temperature X-Ray Diffraction Study of Phase Transformations in Maraging 300 Steel

2017 ◽  
Vol 371 ◽  
pp. 73-77 ◽  
Author(s):  
Adriano Gonçalves Reis ◽  
Danieli Aparecida Pereira Reis ◽  
Antônio Jorge Abdalla ◽  
Antônio Augusto Couto ◽  
Jorge Otubo
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Austenite Transformation ◽  
X Ray ◽  
Xrd Diffraction ◽  
Temperature Solution ◽  
Diffraction Patterns

An in situ high-temperature X-ray diffraction (HTXRD) study in maraging 300 steel was carried out to study the martensite to austenite transformation and effect of time of exposure in the austenite reversion below austenite start temperature. Solution annealed materials were subjected to controlled heating-holding cycles. The first sample was heated at a rate of 10 oC/min from room temperature to 800 oC, showing that the microstructure is completely martensitic (α’110) until 600 oC. From 650 oC until 800 oC, the microstructure is gradually changing from martensitic to austenitic, showed by the increasing peaks of γ111 and reducing peaks of α’110. At 800 oC the microstructure is completely austenitic (γ111). Another sample was heated at 10 oC/min from room temperature to 600 oC and held for 4 hours. At 600 oC, at 0 h time of exposure, only a martensitic peak was observed. An austenite peak can be observed after some time of exposure at this temperature. The volume fraction of austenite increased with increasing time of exposure at 600 oC, reaching 50/50 volume fraction after 4 hours of exposure. XRD diffraction patterns for the same sample that was held for 4 hours at 600 oC and then cooled down in air to room temperature showed the same intensity of austenite and martensitic peaks found in situ at 600 oC for 4 hours (retained austenite), with the volume fraction of 50/50 of austenite and martensite phases. The HTXRD technique can be used to identify and quantify martensite to austenite transformation and austenite retention.

MAGNETIC AND TRANSPORT PROPERTIES OFPr0.7Sr0.3MnO3/La0.5Ca0.5MnO3/Pr0.7Sr0.3MnO3TRILAYERS

2012 ◽  
Vol 26 (23) ◽  
pp. 1250132 ◽  
Author(s):  
H. O. WANG ◽  
P. DAI ◽  
H. LIU ◽  
W. S. TAN ◽  
F. XU ◽  
...  
Keyword(s):  
Transport Properties ◽  
Exchange Bias ◽  
Volume Fraction ◽  
Magnetic Phase ◽  
X Ray Diffraction ◽  
High Crystalline Quality ◽  
Metal Insulator ◽  
X Ray ◽  
Diffraction Patterns ◽  
Oriented Single Crystal

All-manganites Pr0.7Sr0.3MnO3/ La0.5Ca0.5MnO3/ Pr0.7Sr0.3MnO3(PSMO/LCMO/PSMO) trilayers were deposited on (001)-oriented single crystal MgO by pulsed laser deposition. The thickness of both PSMO layers was 36 nm while the thickness of LCMO layer varied from 6 to 36 nm. High resolution X-ray diffraction patterns indicated that trilayers were well (001)-oriented grown with high crystalline quality, and that PSMO layers were fully-strain-relaxed while LCMO spacer was partially strained. Studies on transport and magnetic properties of trilayers indicated that metal-insulator transition temperature TMIincreased from 200 K to 260 K and the saturation magnetization was suppressed with decreasing thickness of LCMO spacer from 36 to 6 nm. Transport properties of trilayers are associated with enhancement of volume fraction of ferromagnetic clusters in charge ordered and magnetic phase separated LCMO spacer. Interestingly, exchange bias (EB) was not observed in PSMO/LCMO/PSMO trilayers. It was believed that preferential distribution of metallic ferromagnetic clusters in LCMO layer may result in disappearance of EB.

scholarly journals ASCA SIS X-ray Observations of the Wind Blown Bubble NGC 6888

1997 ◽  
Vol 166 ◽  
pp. 425-428
Author(s):  
Matthias Wrigge ◽  
You-Hua Chu ◽  
Eugene A. Magnier ◽  
Yuichi Kamata
Keyword(s):  
Heat Conduction ◽  
High Temperature ◽  
Spectral Resolution ◽  
Surface Brightness ◽  
Contact Discontinuity ◽  
Plasma Component ◽  
Central Temperature ◽  
X Ray ◽  
High Temperature Component ◽  
Temperature Component

AbstractWe present ASCA SIS observations of the wind-blown bubble NGC 6888. Because the ASCA SIS is sensitive to higher energy photons and has a higher spectral resolution compared to the ROSAT PSPC, we are able to detect a T ≈ 8×106 K plasma component besides the T ≈ 1.5×106 K component known from previous PSPC observations. The existence of a high-temperature component, the observed limb-brightened X-ray surface brightness profile, and the observed level of X-ray surface brightness cannot be satisfactorily explained by currently available models. Reducing heat conduction at the contact discontinuity may raise the central temperature and produce a limb-brightening; however, the expected X-ray surface brightness is still considerably higher than the observed surface brightness.

High Density Bulk Shape Rapid Consolidation of the Yba2Cu307-X Superconductor

1989 ◽  
Vol 169 ◽  
Author(s):  
S. V. Rele ◽  
R. V. Raman ◽  
H. S. Meeks ◽  
R. L. Anderson ◽  
R. N. Shelton ◽  
...  
Keyword(s):  
Volume Fraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Superconducting Volume Fraction ◽  
One Step ◽  
Hollow Cylinders ◽  
Diffraction Patterns ◽  
Set Up ◽  
Cylinders And Spheres ◽  
High Processing

AbstractA novel rapid densification technique for fabrication of bulk shape YBa2Cu307–xsuperconductor is presented. The Ceracon process is a one‐step, quasi‐isostatic consolidation route utilizing conventional P/M equipment and set‐up. The Ceracon technology has enabled successful fabrication of bulk, shapes such as discs, cylinders, hollow cylinders and spheres along with significant increases in the density up to 95‐98% of the theorertical. The superconducting volume fraction is preserved due to short hold times at the operating temperatures and avoidance of high processing temperatures. Results based on densities, microstructure, susceptibility measurements, X‐ray diffraction patterns and TGA measurements are discussed.

Effects of Donor Doping on Microstructure and Electrical Properties of Bismuth Layer-Structured Bi4Ti3O12 Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 259-262 ◽  
Author(s):  
Lina Zhang ◽  
Su Chuan Zhao ◽  
Liao Ying Zheng ◽  
Guo Rong Li ◽  
Qing Rui Yin
Keyword(s):  
Electrical Conductivity ◽  
High Temperature ◽  
Electrical Properties ◽  
Ferroelectric Properties ◽  
Orthorhombic Phase ◽  
X Ray Diffraction ◽  
Suitable Candidate ◽  
X Ray ◽  
Donor Doping ◽  
Diffraction Patterns

A study was conducted on the effects of donor dopants, Nb2O5 and WO3, on microstructure and electric properties of Bi4Ti3O12 (BIT) ceramics. X-ray diffraction patterns of the materials showed a single orthorhombic phase structure. The microstructure results revealed the appearance of plate-like grain. The donor doping decreased the conductivity of BIT by as much as 3 orders of magnitude. The dielectric and ferroelectric properties of doped-BIT materials were also investigated. The decrease in the electrical conductivity allowed the doped samples to be poled to develop piezoelectricity. Thermal annealing studies of the samples indicated the donor-doped BIT were suitable candidate materials for high-temperature piezoelectric applications.

Comments on determining X-ray diffraction-based volume fractions of retained austenite in steels

2001 ◽  
Vol 16 (4) ◽  
pp. 198-204 ◽  
Author(s):  
C. K. Lowe-Ma ◽  
W. T. Donlon ◽  
W. E. Dowling
Keyword(s):  
Retained Austenite ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Profile Fitting ◽  
Diffraction Peaks ◽  
Diffraction Patterns ◽  
Heat Treatment Regimes ◽  
Integrated Intensities

Retained austenite is an important characteristic of properly heat-treated steel components, particularly gears and shafts, that will be subjected to long-term use and wear. Normally, either X-ray diffraction or optical microscopy techniques are used to determine the volume percent of retained austenite present in steel components subjected to specific heat-treatment regimes. As described in the literature, a number of phenomenological, experimental, and calculation factors can influence the volume fraction of retained austenite determined from X-ray diffraction measurements. However, recent disagreement between metallurgical properties, microscopy, and service laboratory values for retained austenite led to a re-evaluation of possible reasons for the apparent discrepancies. Broad, distorted X-ray peaks from un-tempered martensite were found to yield unreliable integrated intensities whereas diffraction peaks from tempered samples were more amenable to profile fitting with standard shape functions, yielding reliable integrated intensities. Retained austenite values calculated from reliable integrated intensities were found to be consistent with values obtained by Rietveld refinement of the diffraction patterns. The experimental conditions used by service laboratories combined with a poor choice of diffraction peaks were found to be sources of retained austenite values containing significant bias.

Barium hollandite-type compounds BaxFe2xTi8−2xO16 with x=1.143 and 1.333

1999 ◽  
Vol 14 (1) ◽  
pp. 31-35 ◽  
Author(s):  
J. M. Loezos ◽  
T. A. Vanderah ◽  
A. R. Drews
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Powder Diffraction ◽  
Framework Structure ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns ◽  
Acta Crystallogr

Experimental X-ray powder diffraction patterns and refined unit cell parameters for two barium hollandite-type compounds, BaxFe2xTi8−2xO16, with x=1.143 and 1.333, are reported here. Compared to the tetragonal parent structure, both compounds exhibit monoclinic distortions that increase with Ba content [Ba1.333Fe2.666Ti5.334O16: a=10.2328(8), b=2.9777(4), c=9.899(1) Å, β=91.04(1)°, V=301.58(5) Å3, Z=1, ρcalc=4.64 g/cc; Ba1.143Fe2.286Ti5.714O16: a=10.1066(6), b=2.9690(3), c=10.064(2) Å, β=90.077(6)°, V=301.98(4) Å3, Z=1, ρcalc=4.48 g/cc]. The X-ray powder patterns for both phases contain a number of broad, weak superlattice peaks attributed to ordering of the Ba2+ ions within the tunnels of the hollandite framework structure. According to the criteria developed by Cheary and Squadrito [Acta Crystallogr. B 45, 205 (1989)], the observed positions of the (0k1)/(1k0) superlattice peaks are consistent with the nominal x-values of both compounds, and the k values calculated from the corresponding d-spacings suggest that the Ba ordering within the tunnels is commensurate for x=1.333 and incommensurate for x=1.143. High-temperature X-ray diffraction data indicate that the x=1.333 compound undergoes a monoclinic→tetragonal phase transition between 310 and 360 °C.

Densification Behaviour of Nano-Size CeO2

2007 ◽  
Vol 555 ◽  
pp. 189-194 ◽  
Author(s):  
D. Djurović ◽  
Matvei Zinkevich ◽  
Snezana Bošković ◽  
V. Srot ◽  
Fritz Aldinger
Keyword(s):  
High Temperature ◽  
Redox Reaction ◽  
Lattice Parameter ◽  
Oxygen Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Densification Behaviour ◽  
Air Atmosphere ◽  
Diffraction Patterns ◽  
Lower Temperature

A nano-sized CeO2 powder was synthesized by a modified glycine nitrate process (MGNP). The synthesized powder was characterized by X-ray diffraction (XRD), the Brunauer Emmett Teller (BET) method, and transmission electron microscopy (TEM). The lattice parameter and crystallite size were determined by the Rietveld refinement of X-ray diffraction patterns. The shrinkage kinetics of the green body was continuously monitored in air and in oxygen atmospheres using a high temperature dilatometer up to 1500°C. During the high temperature sintering in air a redox reaction occurred (Ce4+ was partially reduced to Ce3+, and oxygen gas was released). The redox reaction influenced the sintering behaviour of CeO2, resulting in a decrease in density. On the basis of shrinkage kinetics data in oxygen atmosphere a master sintering curve for CeO2 was constructed. Using the concept of the master sintering curve, the densification behaviour in oxygen atmosphere was successfully predicted from early to final stages of sintering. During sintering of CeO2 at lower temperature in air atmosphere a significant contribution of the surface diffusion was observed.

Residual Stresses in Aluminum-Mullite (α-Alumina) Composites*

1992 ◽  
Vol 36 ◽  
pp. 489-497
Author(s):  
Davor Balzar ◽  
Hassel Ledbetter
Keyword(s):  
Volume Fraction ◽  
Mechanical Equilibrium ◽  
X Ray Diffraction ◽  
Particle Volume ◽  
X Ray ◽  
The Matrix ◽  
Alumina Composites ◽  
Diffraction Patterns ◽  
Small Anisotropy ◽  
Three Phases

AbstractWe studied particle-reinforced 6061-aluminum-alloy composites with particle volume fractions ranging from 0 to 0.25. The mullite particles are approximately spherical and contain embedded α-alumina phase. We obtained lattice parameters of all three phases in the composites and starting materials by using Rietveld refinement of x-ray diffraction patterns. In all three phases stresses are tensile and approximately of the same magnitude, contradicting a requirement for mechanical equilibrium. Stresses increase with both increasing particle size and volume fraction. Measurements of extracted-from-composites particles showed no evidence of a possible chemical reaction at the matrix-particle interface. The matrix is [111] and [100] textured, but measurements of elastic constants reveal only small anisotropy. Thus, explanation of the mechanical-equilibrium violation remains uncertain.

scholarly journals In Situ High Temperature X-Ray Studies on Bainitic Transformation of Austempered Silicon Alloyed Steels

2010 ◽  
Vol 638-642 ◽  
pp. 3086-3092 ◽  
Author(s):  
Esa Vuorinen ◽  
Xiang Chen
Keyword(s):  
High Temperature ◽  
Volume Fraction ◽  
Early Stage ◽  
Bainitic Transformation ◽  
Experimental Results ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Heterogeneous Distribution ◽  
X Ray

The in-situ X-ray diffraction observations of the bainitic transformation of silicon alloyed steels were performed using the high temperature X-ray diffraction technique. The experimental results have shown that the volume fraction and carbon content of austenite remains a constant value which indicate that the transformation is almost finished after the early stages of austempering transformation. Asymmetry diffraction peaks are obtained for samples at the early stage of transformation due to a heterogeneous distribution of carbon in different regions of austenite and thus exists two types of austenite: low-carbon austenite (γLC) and the high-carbon austenite (γHC). The experimental results supports that the bainite growth is by a non-diffusive mechanism when austempering temperature is in the lower bainite transformation temperature.

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