Correlated Decrease between the Superconducting Volume Fraction and Tc and Possible Phase Separation in the Overdoped Regime of La2−xSrxCuO4

2006 ◽  
Author(s):  
Y. Tanabe ◽  
T. Adachi ◽  
T. Noji ◽  
H. Sato ◽  
Y. Koike
Keyword(s):  
Phase Separation ◽  
Volume Fraction ◽  
Superconducting Volume Fraction

Porous Gel Coatings Obtained by Phase Separation in ORMOSIL System

2000 ◽  
Vol 628 ◽  
Author(s):  
Kazuki Nakanishi ◽  
Souichi Kumon ◽  
Kazuyuki Hirao ◽  
Hiroshi Jinnai
Keyword(s):  
Phase Separation ◽  
Reaction Time ◽  
Volume Fraction ◽  
Sol Gel ◽  
Reaction Times ◽  
Dip Coating ◽  
Coating Solution ◽  
Coating Method ◽  
Gel Phase ◽  
Dip Coating Method

ABSTRACTMacroporous silicate thick films were prepared by a sol-gel dip-coating method accompanied by the phase separation using methyl-trimethoxysilane (MTMS), nitric acid and dimethylformamide (DMF) as starting components. The morphology of the film varied to a large extent depending on the time elapsed after the hydrolysis until the dipping of the coating solution. On a glass substrate, the films prepared by early dipping had inhomogeneous submicrometer-sized pores on the surface of the film. At increased reaction times, relatively narrow sized isolated macropores were observed and their size gradually decreased with the increase of reaction time. On a polyester substrate, in contrast, micrometer-sized isolated spherical gel domains were homogeneously deposited by earlier dippings. With an increase of reaction time, the volume fraction of the gel phase increased, then the morphology of the coating transformed into co-continuous gel domains and macropores, and finally inverted into the continuous gel domains with isolated macropores. The overall morphological variation with the reaction time was explained in terms of the phase separation and the structure freezing by the forced gelation, both of which were induced by the evaporation of methanol during the dipping operation.

APPLICATION OF ESR TO HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS IV: ALKALI K DOPING EFFECTS ON THE SUPERCONDUCTING CHARACTERISTICS OF K3C60

1999 ◽  
Vol 13 (02) ◽  
pp. 59-69
Author(s):  
K. SUGAWARA ◽  
N. OHYA ◽  
N. ARAI ◽  
S. ICHIMURA ◽  
K. YAMAMOTO ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Calcination Temperature ◽  
Volume Fraction ◽  
Superconducting Properties ◽  
High Tc Superconductors ◽  
High Tc ◽  
Doping Effects ◽  
Superconducting Volume Fraction ◽  
Vortex Size ◽  
Quartz Tubes

Several samples of K 3 C 60 have been made by the calcination of C 60 powder plus K flakes in evacuated quartz tubes at temperatures between 100°C and 700°C for 24 hours. The non-resonant microwave absorption (NRMA) measurements have been done below T c for these samples. From the linewidths and intensities of the NRMA signals, the superconducting properties (T c superconducting volume fraction and vortex size) have been studied as a function of the calcination temperature.

Transmission Electron Microscopy (TEM) Observations of Phase-Separations of Gamma-Prime Precipitates in Ni-Al-Fe and Ni-Si-Fe Ternary Alloys

2007 ◽  
Vol 26-28 ◽  
pp. 1311-1314 ◽  
Author(s):  
M. Senga ◽  
H. Kumagai ◽  
Tomokazu Moritani ◽  
Minoru Doi
Keyword(s):  
Phase Separation ◽  
Volume Fraction ◽  
Heating Temperature ◽  
Ternary Alloys ◽  
Phase System ◽  
Precipitate Phase ◽  
Two Phase ◽  
Gamma Prime ◽  
Transmission Electron ◽  
The Difference

In Ni-13.0at%Si-3.1at%Fe alloy, when γ/γ’ two-phase microstructure formed at 1123 K is isothermally heated at 923 K which is lower than the temperature where the initial γ/γ’ microstructure forms, the phase-separation of γ/γ’ precipitate phase occurs and γ particles newly appear in each cuboidal γ’ precipitate. While in Ni-10.2at%Al-10.8at%Fe alloy, when γ/γ’ two-phase microstructure formed at 1023 K is isothermally heated at 1123 K which is higher than the temperature where the initial γ/γ’ microstructure forms, the phase-separation of γ’ precipitate phase takes place and γ particles newly appear in each cuboidal γ’ precipitate. Such appearance of new γ particles in γ’ precipitates can be explained by the difference in the volume fraction of γ phase that should exist in the γ/γ’ two-phase system depending on the heating temperature.

EFFECT OF COOLING RATE ON THE TRANSITION TEMPERATURE IN Bi–Pb–Sr–Ca–Cu–O SYSTEM

1990 ◽  
Vol 04 (04) ◽  
pp. 293-299
Author(s):  
YUGUI WANG ◽  
JINSONG WANG ◽  
NANLIN WANG ◽  
XINPING JIAO ◽  
GUCHANG HAN ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Specific Heat ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Oxygen Deficiency ◽  
Ac Susceptibility ◽  
Rapid Quenching ◽  
Nominal Composition ◽  
Unit Cell Size ◽  
Superconducting Volume Fraction

The resistance and ac susceptibility measurements show that cooling rate of the cast-annealing samples in heat treatment process has some effect on the 110 K superconducting phase in Bi–Pb–Sr–Ca–Cu–O system. Rapid quenching of the sample in air from 845°C causes oxygen deficiency in lattice and brings about a trifling change of unit cell size along c-axis direction. The dc magnetization and specific heat anomaly ∆c measurements demonstrate that fast cooling rate can reduce the transition temperature of high T c phase and the lower critical field, and weaken the pinning forces for vertex lines. The peak value of specific heat anomaly of the sample with nominal composition of Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 4.5 O y is still small in comparison with YBa 2 Cu 3 O 7. From the magnetization curve we can estimate that the superconducting volume fraction is about 20%.

scholarly journals Quantitative Phase-Field Simulation of Composition Partition and Separation Kinetics of Nanoscale Phase in Fe-Cr-Al Alloy

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Shi Chen ◽  
Yongsheng Li ◽  
Shujing Shi ◽  
Shengshun Jin
Keyword(s):  
Phase Separation ◽  
Phase Field ◽  
Ostwald Ripening ◽  
Volume Fraction ◽  
Phase Interface ◽  
Al Alloy ◽  
Average Particle ◽  
Phase Field Simulation ◽  
Field Simulation ◽  
Separation Kinetics

Phase separation of the Cr-enriched nanoscale α′ phase in the Fe-38 at.% Cr-10 at.% Al alloy is studied by utilizing phase-field simulation. The partition of elements in the α and α′ phases is clarified with the composition evolution through the α/α′ phase interface, and the separation kinetics is quantitatively investigated by the temporal evolution of the size and volume fraction of the α′ phase. Aluminum partitions into the Fe-enriched α phase and depletes in the α′ phase, and the partition coefficient decreases as the temperature changes from 720 K to 760 K for the steady-state coarsening stage. As the temperature increases, the initial change rate of the volume fraction of the α′ phase is faster, indicating an accelerated phase separation. At the coarsening stage, the average particle distance and coarsening rate constant of the α′ phase increase with increased temperature, and the ratio of the Ostwald ripening is dominating compared with coalescence coarsening. The element partition and kinetics evolution of the α′ phase with temperature are helpful for the morphology and property predication of nanoscale precipitates.

Mechanical and Structural Properties of Maltodextrin/Agarose Gel Composites

2006 ◽  
Vol 16 (5) ◽  
pp. 248-257 ◽  
Author(s):  
Chrystel Loret ◽  
William J. Frith ◽  
Peter J. Fryer
Keyword(s):  
Mechanical Properties ◽  
Phase Separation ◽  
Confocal Microscopy ◽  
Large Deformation ◽  
Mechanical Behaviour ◽  
Composite Structure ◽  
Volume Fraction ◽  
Dispersed Phase ◽  
Agarose Gel ◽  
Mechanical And Structural Properties

Abstract When two biopolymers are mixed together, they will normally phase separate to give two distinct phases. If the biopolymers are gelled during this phase separation, for instance by reducing the temperature, one phase is trapped in this other one and an emulsion-like composite structure is obtained. In this study, we investigated the effect of volume fraction and droplet size of this dispersed phase on the mechanical properties of maltodextrin/agarose gel composites, where agarose is the dispersed phase. Mechanical properties of the different composites were investigated under large deformation using a rheometer with a vane geometry. These composites were also observed by confocal microscopy, allowing conclusions to be drawn regarding the microstructural origins of the observed mechanical behaviour.

Effect of the species of substituted ion on ferroelastic domain switching of rare-earth ion-doped ZrO2 pseudo-single crystals

1999 ◽  
Vol 14 (1) ◽  
pp. 142-145 ◽  
Author(s):  
Takanori Kiguchi ◽  
Atsushi Saiki ◽  
Kazuo Shinozaki ◽  
Nobuyasu Mizutani
Keyword(s):  
Rare Earth ◽  
Phase Separation ◽  
Single Crystals ◽  
Domain Switching ◽  
Volume Fraction ◽  
Rare Earth Ion ◽  
Microstructural Aspect ◽  
The Difference

The difference of domain switching amount of 3 mol% R2O3−ZrO2 (R = Yb, Y, Dy, Gd, Eu, Sm) pseudo-single crystals with additive cation species was investigated from the microstructural aspect. The switching amount of Yb, Y, Dy, and Gd substituted ZrO2 was three times higher than that of Eu and Sm. The amount corresponded to the volume fraction of the t′-phase, and it indicated that phase separation proceeded, especially in Eu and Sm substituted ZrO2.

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