Effect of Oxidizing Atmosphere on Superconductivity in RBa2Cu3−xMxOz

1987 ◽  
Vol 99 ◽  
Author(s):  
David A. Robinsonem ◽  
Abbot Maginnis ◽  
A. Morrobel-Sosa ◽  
Chester Alexander ◽  
C. Asavaroengchai ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Electrical Resistance ◽  
Single Phase ◽  
Analysis Data ◽  
Nominal Composition ◽  
Superconducting Properties ◽  
Metal Substitution ◽  
Critical Temperatures ◽  
X Ray ◽  
Heat Treated

ABSTRACTThe dependence of the superconducting properties of RBa2Cu3−xMxOz (R = Y, Gd, M = Cr, Mn, Fe, Co, Ni, and x = 0.0, 0.025, 0.05, 0.1, 1.0, 3.0) on the oxidizing environment used during the processing (sintering/annealing) of these materials has been investigated. Samples of nominal composition, YBa2Cu3Oz, were prepared from the same starting materials and subjected to two different controlled heat treatments, under both controlled oxygen and ozone atmospheres. Measurements of ac electrical resistance versus temperature indicate that the critical temperatures are increased, and the widths of the superconducting transitions are narrowed for identically heat-treated samples when processed under ozone atmosphere rather than under an oxygen environment. Thermogravimetric analysis data indicate this trend to be correlated with increased oxygen content and thermal stability. This effect is also observable for materials with metal substitution for Cu, although the measured Tc's are generally lower for increased values of x. X-ray powder diffraction analysis showed the materials to be mostly single phase.

The Effect of Sheath Materials on the Superconductivity of MgB2

2001 ◽  
Vol 689 ◽  
Author(s):  
W. Zhu ◽  
D. R. Watson ◽  
J. R. Cave
Keyword(s):  
Palladium Alloy ◽  
Processing Conditions ◽  
Squid Magnetometry ◽  
Superconducting Properties ◽  
Critical Temperatures ◽  
X Ray ◽  
Heat Treated ◽  
Magnetization Data ◽  
Silver Palladium ◽  
Powder In Tube

ABSTRACTInconel, tantalum and a silver-palladium alloy were used to fabricate MgB2tapes. The tapes, made by the Powder In Tube (PIT) method, were heat-treated at 800°C and 900°C in 1 atmosphere of flowing argon. The microstructure and phase composition of the tapes were examined by Scanning Electron Microscopy (SEM) and X-Ray Diffractometry (XRD). Critical temperatures (Tc) and magnetization-applied magnetic field (M-H) curves were measured by SQUID magnetometry. It is found that between 800–900°C inconel and tantalum sheaths have no effect on the Tc,inductive of the material. However, under certain processing conditions, the silver-palladium sheath can decrease the Tcor destroy the superconductivity completely. The inconel sheathed tape was found to have better superconducting properties than the tantalum and silver-palladium sheathed tapes. Consistency checks have been applied to verify the validity of the Bean Model in obtaining the critical current density (Jc) from magnetization data. The inconel sheathed tape is estimated to have a magnetization Jc(5K, ∼0.5 T) of 1.4 × 105A/cm2.

TIN ADDITION TO THE (Bi, Pb) 2223 SYSTEM

1994 ◽  
Vol 08 (19) ◽  
pp. 1175-1183 ◽  
Author(s):  
G. RAVI CHANDRA ◽  
B. GOPALA KRISHNA ◽  
S. V. SURYANARAYANA ◽  
T. S. N. MURTHY
Keyword(s):  
Heat Treatment ◽  
Magnetic Susceptibility ◽  
Electrical Resistance ◽  
Volume Fraction ◽  
Ac Magnetic Susceptibility ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Metallic Behavior ◽  
X Ray

The effect of the addition of Sn on the superconducting properties of the Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 3 O y system as functions of Sn concentration and heat treatment has been studied by dc electrical resistance, ac magnetic susceptibility, and X-ray diffraction. Tin addition suppresses the volume fraction of the high T c phase. Samples with Sn > 0.1 show metallic behavior up to LNT. The formation of the Ca 2 PbO 4 phase is promoted by Sn. This depletes the amount of Pb and Ca necessary for the formation of the 2223 phase, thus reducing the volume fraction of the 2223 phase. It is possible that at least a small fraction of tin substitutes some of the cationic sites of the starting composition. The results of the different measurements are presented.

scholarly journals Mn-Induced Thermal Stability of L10 Phase in Fept Magnetic Nanoscale Ribbons

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1278
Author(s):  
Alina Daniela Crisan ◽  
Aurel Leca ◽  
Dan Pantelica ◽  
Ioan Dan ◽  
Ovidiu Crisan
Keyword(s):  
Rare Earth ◽  
Single Phase ◽  
Permanent Magnets ◽  
Magnetic Hysteresis ◽  
Ternary Alloys ◽  
Large Temperature ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Operation Conditions

Magnetic nanoscale materials exhibiting the L10 tetragonal phase such as FePt or ternary alloys derived from FePt show most promising magnetic properties as a novel class of rare earth free permanent magnets with high operating temperature. A granular alloy derived from binary FePt with low Pt content and the addition of Mn with the nominal composition Fe57Mn8Pt35 has been synthesized in the shape of melt-spun ribbons and subsequently annealed at 600 °C and 700 °C for promoting the formation of single phase, L10 tetragonal, hard magnetic phase. Proton-induced X-ray emission spectroscopy PIXE has been utilized for checking the compositional effect of Mn addition. Structural properties were analyzed using X-ray diffraction and diffractograms were analyzed using full profile Rietveld-type analysis with MAUD (Materials Analysis Using Diffraction) software. By using temperature-dependent synchrotron X-ray diffraction, the disorder–order phase transformation and the stability of the hard magnetic L10 phase were monitored over a large temperature range (50–800 °C). A large interval of structural stability of the L10 phase was observed and this stability was interpreted in terms of higher ordering of the L10 phase promoted by the Mn addition. It was moreover found that both crystal growth and unit cell expansion are inhibited, up to the highest temperature investigated (800 °C), proving thus that the Mn addition stabilizes the formed L10 structure further. Magnetic hysteresis loops confirmed structural data, revealing a strong coercive field for a sample wherein single phase, hard, magnetic tetragonal L10 exists. These findings open good perspectives for use as nanocomposite, rare earth free magnets, working in extreme operation conditions.

Synthesis and Characterization of T12Ba2CaCu2O8 and T12Ba2Ca2Cu3O10

1989 ◽  
Vol 169 ◽  
Author(s):  
Lauren E. H. McMills ◽  
Shu Li ◽  
Zhen Zhang ◽  
Martha Greenblatt
Keyword(s):  
Magnetic Susceptibility ◽  
Powder Diffraction ◽  
Single Phase ◽  
Synthesis And Characterization ◽  
Synthetic Method ◽  
Superconducting Properties ◽  
X Ray ◽  
Preparation Conditions ◽  
The Relationship

AbstractSingle-phase samples of T12Ba2CaCu2O8 and T12Ba2Ca2Cu3O10 have been prepared using a reliable and simple synthetic method. Samples were characterized by x-ray powder diffraction, magnetic susceptibility and four probe resistivity methods. The TcR=0 values for T12Ba2CaCu2O8 ranged from 100 to 105K, whereas those for T12Ba2Ca2Cu3O10 ranged from 96 to 107K. The relationship between the superconducting properties and the various preparation conditions are discussed.

Synthesis and Magnetic Properties of La-Doped Ni Ferrites

2010 ◽  
Vol 148-149 ◽  
pp. 736-739
Author(s):  
Ju Hua Luo
Keyword(s):  
Single Phase ◽  
Raw Materials ◽  
Nominal Composition ◽  
Vibrating Sample Magnetometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Magnetic Parameters ◽  
Ft Ir ◽  
Mechanochemical Treatments ◽  
La Doped

Ni ferrites doped with lanthanum with a nominal composition of NiFe2-xLaxO4(x=0.05) were obtained by mechanochemical treatments using NiCO3•2Ni (OH)2•4H2O , La2O3 and Fe2O3 as raw materials. Both series of materials were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM). The results indicated that the mixture became amorphous stage after ball-milled for 30 h, and single phase NiFe1.95La0.05O4 could be obtained after calcined at 700 for 2 h. The addition of lanthanum resulted in a reduction of all the magnetic parameters evaluated.

Investigation on the Thermal Stability of the Compounds Y3Fe29-xCrx

2013 ◽  
Vol 820 ◽  
pp. 71-74
Author(s):  
Xiao Hua Wang ◽  
Wei He ◽  
Ling Min Zeng
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Single Phase ◽  
Binary Compound ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Transition Elements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Stability Of

Binary compound Y3Fe29cannot be directly formed by rare earth Y and Fe and the third element M (non-iron transition elements) must be introduced to form ternary compound Y3(Fe,M)29. In this work, six alloys with compositions of the Y3Fe29-xCrx(x=1,2,3,4,5,6) were prepared and investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and differential thermal analysis (DTA). The study on the thermal stability of these compounds points to that the compoundY3(Fe,Cr)29is a high temperature phase and exists above 1100K. The alloys with single-phase of Y3(Fe,Cr)29was decomposed into Y2(Fe,Cr)17and Y(Fe,Cr)12annealed at high temperature 1100K.

STUDY OF Y1-xCaxBa2-yLayCu3Oz CARRIER UN-COMPENSATING SYSTEM

2009 ◽  
Vol 23 (25) ◽  
pp. 5039-5047
Author(s):  
W. T. JIN ◽  
S. J. HAO ◽  
H. ZHANG ◽  
Y. ZHAO
Keyword(s):  
Critical Temperature ◽  
Carrier Concentration ◽  
Single Phase ◽  
Magnetization Measurement ◽  
The Self ◽  
Careful Study ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Lengths

The single-phase samples of Y 0.9 Ca 0.1 Ba 2-y La y Cu 3 O z and Y1-x Ca x Ba 1.5 La 0.5 Cu 3 O z were synthesized with both x and y from 0 to 0.5, respectively. Structural and superconducting properties have been investigated by X-ray diffraction, Rietveld refinement, and DC magnetization measurement, respectively. Different from the self-compensating compound of Y 1-x Ca x Ba 2-x La x Cu 3 O z, carriers in these two systems of Y1-x Ca x Ba 2-y La y Cu 3 O z are not compensated as x ≠ y. By careful study of the chemical bond lengths related to Cu (2)– O plane and Cu (1)– O chain, it is demonstrated that the critical temperature (Tc) changes monotonously with the bond lengths of Cu (1)– O (4) and Cu (2)– O (4). The analysis demonstrates that crystalline structure is one of the important factors to high-Tc superconductivity, and its influence is independent of the carrier concentration.

scholarly journals Structural and Electron-Hopping Studies of Pr and Nd Substituted La2/3Ba1/3MnO3 Manganites

2009 ◽  
Vol 282 ◽  
pp. 1-8
Author(s):  
Abdullah Huda ◽  
S.A. Halim
Keyword(s):  
Electrical Resistance ◽  
Single Phase ◽  
Microstructural Properties ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Resistivity Measurements ◽  
Structural And Electrical Properties ◽  
Lower Temperature ◽  
Xrd Patterns ◽  
Semiconducting Behavior

The significance of substituting concentrations of Pr and Nd at La-sites, in La0.67Ba0.33MnO3 perovskite compounds, for the structural and electrical properties have been studied. Polycrystalline samples (La1-x Prx)0.67Ba0.33MnO3 and (La1-x Ndx)0.67Ba0.33MnO3 with x = 0.00, 0.167, 0.333, 0.5, 0.667, 0.833 and 1.0 were synthesized via conventional solid-state reaction in the bulk. All of the samples were calcined at 900oC for 12 hours, pelletized and sintered at 1300oC for 24 hours and investigated. In this paper the structural patterns and microstructural properties of bulk samples have been investigated via x-ray diffractometry (XRD) and scanning electron microscopy (SEM). XRD patterns show that these systems are single-phase, with orthorhombic distorted perovskite structures. The electrical property, Tp, was determined by using standard four-point probe resistivity measurements in the temperature range of 20 K to 300 K. The result shows that Pr and Nd dopants shift the value of TP to a lower temperature. When the temperature is above Tp, T > Tp, the variation of the electrical resistance was found to follow the an Arhenius-type law, ρ = ρo exp (-Ea/KBT). It was used to calculate the activation energy of every sample. The resistivity curves show semiconducting behavior of all samples above their Tp.

The Transformation of Co-Rich Alloys Produced by Mechanical Alloying

2006 ◽  
Vol 509 ◽  
pp. 135-140
Author(s):  
Francisco Cruz-Gandarilla ◽  
R. Gayosso-Armenta ◽  
J. Gerardo Cabañas-Moreno ◽  
Heberto Balmori-Ramírez
Keyword(s):  
Single Phase ◽  
Intermetallic Phase ◽  
High Energy ◽  
Inert Atmosphere ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Powder Mixtures ◽  
X Ray ◽  
Heat Treated ◽  
Energy Ball

Elemental powder mixtures of Co and Ti were subjected to high-energy ball milling in order to produce mechanically alloyed powders with nominal compositions Co64Ti36, Co67Ti33, Co70Ti30, Co73Ti27, Co76Ti24 and Co85Ti15. The mechanically alloyed powders were treated during 30 minutes in inert atmosphere at temperatures in the range 300 – 700 °C. Both the as-milled powders as well as those subjected to heat treatments have been characterized by x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectrometry and differential thermal analysis. As-milled products consist mostly of agglomerated powders with a size between 10 and 80 µm which give an amorphous-like diffraction pattern, except for the Co85Ti15 sample whose pattern presents the characteristic peaks of the Co3Ti intermetallic phase. The transformation of the asmilled powders occurs at temperatures in the range of about 530 – 670 °C with clearly observed exothermic events. The Co3Ti phase is found in all heat treated samples, together with fcc-Co (in Co76Ti24 and Co85Ti15) or the hexagonal Co2Ti intermetallic phase (in Co64Ti36, Co67Ti33 and Co70Ti30); the Co73Ti27 sample was essentially single-phase Co3Ti after heating to 700 °C. Our results suggest the occurrence of crystallization of an amorphous phase in two overlapping stages during heating of the mechanically alloyed powders.

Decomposition of an Al-Cu-Ru quasi-crystal at 1420 K

1996 ◽  
Vol 54 ◽  
pp. 718-719
Author(s):  
Y. Kitano ◽  
Y. Fujikawa ◽  
T. Watanabe
Keyword(s):  
High Temperature ◽  
Phase I ◽  
Icosahedral Phase ◽  
Thermal Reaction ◽  
Nominal Composition ◽  
X Ray ◽  
Epma Analysis ◽  
Heat Treated ◽  
Lower Temperature ◽  
Quasi Crystals

Quasi–crystals of Al65Cu20RU15 alloy are known to be an icosahedral— phase (I— phase) of the F–type. This state has been confirmed to be stable near 1100 K, but perhaps not at temperatures higher than around 1300 K. In this paper we report high temperature behavior of this alloy. We have found that the stable I-phase would decompose into three or four phases at 1420 K, one of which is an I–phase having a different composition. We denote the lower temperature I–phase, I–phase(L), and this high temperature one, I–phase(H).5N Al and Cu and 3N Ru were arc-melted in Ar. The nominal composition of the alloy was 65A1, 20Cu and 15Ru. In order to obtain homogeneous materials, the ingot was annealed at 1020 K for 100 hours. The X-ray powder diffraction pattern confirmed that the heat-treated ingot was only I-phase(L). This is the starting material in this study. DTA and EPMA analysis, and SEM and TEM observations were carried out in order to investigate subsequence thermal reaction. Experimental results with brief discussion are as follows.

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