SUPERCONDUCTIVITY IN THE U-Y-Ba-Cu-O SYSTEM

1987 ◽  
Vol 01 (07n08) ◽  
pp. 323-326 ◽  
Author(s):  
Q.Z. QIN ◽  
A.D. HE ◽  
W.J. JIA ◽  
L.D. MA ◽  
Z.Y. HUA
Keyword(s):  
Single Phase ◽  
Ambient Pressure ◽  
Raw Material ◽  
Material Structure ◽  
Nominal Composition ◽  
Uranium Oxides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zero Resistance ◽  
Superconducting Oxides

High Tc superconductivity has been observed in a new U-Y-Ba-Cu-O system at ambient pressure. The zero-resistance temperature in the sample with nominal composition of U0.1Y1.1Ba0.8CuO4−δ is 87K with a width of 2K. X-ray diffraction analysis shows that none of the peaks could be fitted to the uranium oxides and the other raw material structure, and its pattern might be attributed to new multiple phases with structure different from the known single-phase superconducting oxides.

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.

Preparation and Property of Al87Ce3Ni8.5Mn1.5 Nanophase Amorphous Composites

2011 ◽  
Vol 412 ◽  
pp. 263-266
Author(s):  
Hong Wei Zhang ◽  
Li Li Zhang ◽  
Feng Rui Zhai ◽  
Jia Jin Tian ◽  
Can Bang Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
Volume Fraction ◽  
Material Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures

The higher mechanical strength of Al87Ce3Ni8.5Mn1.5 nanophase amorphous composites has been obtained with two methods. The first nanophase amorphous composites are directly produced by the single roller spin quenching technology. The method taken for the second nanophase amorphous composites is at first to obtain amorphous single-phase alloy, followed by annealed at different temperatures .The formative condition, the microstructure, the particle size, the volume fraction of α-Al phase and microhardness of nanophase amorphous composites etc have been investigated and compared by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The microstructure of composites produced by the second method is higher than the former, the fabricated material structure of the system is more uniform and the process is easier to control.

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.

REBa2ZrO5.5 (RE = La, Ce, Eu, and Yb): Synthesis, characterization, and their potential use as substrates for YBa2Cu3O7–δ superconductors

1997 ◽  
Vol 12 (11) ◽  
pp. 2976-2980 ◽  
Author(s):  
R. Jose ◽  
Asha M. John ◽  
J. Kurian ◽  
P. K. Sajith ◽  
J. Koshy
Keyword(s):  
Single Phase ◽  
Detrimental Effect ◽  
Solid State Reaction Method ◽  
Dielectric Constants ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
New Class ◽  
Zero Resistance ◽  
Potential Use

A new class of complex perovskites REBa2ZrO5.5 (where RE = La, Ce, Eu, and Yb) have been synthesized and sintered as single phase materials by the solid state reaction method. The structure of these materials was studied by x-ray diffraction, and all of them were found to be isostructural, having a cubic perovskite structure. X-ray diffraction and resistivity measurements have shown that there is no detectable chemical reaction between YBa2Cu3O7–delta; and REBa2ZrO5.5 even under severe heat treatment at 950 °C, and that the addition of REBa2ZrO5.5 up to 20 vol.% in YBa2Cu3O7–δ shows no detrimental effect on the superconducting properties of YBa2Cu3O7-δ. Dielectric constants and loss factors are in the range suitable for their use as substrates for microwave applications. Thick films of YBa2Cu3O7–δ fabricated on polycrystalline REBa2ZrO5.5 substrates gave a zero resistance transition temperature Tc(0) ∼ 92 K, indicating the suitability of these materials as substrates for YBa2Cu3O7–δ.

Sol-Gel Synthesis of the Strontium-Copper Oxycarbonate Superconductor Sr2CuO2(CO3)1−x(BO3)x

1996 ◽  
Vol 453 ◽  
Author(s):  
Audrey J. Babcock ◽  
Alexander R. Pico ◽  
Catherine J. Page
Keyword(s):  
Ambient Pressure ◽  
Sol Gel ◽  
Subsequent Treatment ◽  
Nominal Composition ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gel Preparation ◽  
Starting Solutions ◽  
Sol Gel Synthesis

AbstractWe have developed an ambient-pressure sol-gel synthetic route to superconducting borate-doped Sr2CuO2(CO3) using polyether alkoxide precursors. In our sol-gel preparation, the starting solutions contain strontium and copper alkoxide complexes in 2-(2-methoxy-ethoxy)ethanol. Boron is incorporated into the solution by using an aqueous boric acid solution for hydrolysis. Dried gels were examined by x-ray diffraction and thermal gravimetric analysis. By experimenting with various firing sequences and atmospheres we have established a successful route for reproducibly preparing relatively pure Sr2CuO2CO3 and boron-doped phases. Final products were characterized by x-ray diffraction, elemental analysis and magnetic susceptibility. Samples of nominal composition Sr2CuO2(CO3)0.85(BO2)0.15 are superconducting with a Tc(onset) of ∼25K. Subsequent treatment at 1100°C and 3 GPa for one hour increased Tc(onset) to ∼35K.

SUPERCONDUCTIVITY AND STRUCTURES OF MBa2Cu3O7−x (WITH M = Y, Eu AND Yb) OXIDES

1988 ◽  
Vol 02 (06) ◽  
pp. 1407-1410 ◽  
Author(s):  
M. N. KHAN ◽  
S. Al-DALLAL ◽  
A. MEMON
Keyword(s):  
Tetragonal Phase ◽  
Perovskite Structure ◽  
Single Phase ◽  
Chemical System ◽  
Temperature Transition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ir Studies ◽  
Zero Resistance ◽  
Orthorhombic Perovskite

We have prepared and observed that the zero-resistance temperature transition occurs in the chemical system MBa 2 Cu 3 O 7 (M = Y, Eu and Yb). The highest T c (ρ = 0) is 92.50 K for Y, 93.80 K for Eu and 96.00 for Yb. The X-ray diffraction analysis shows that these compounds correspond to a single phase which is an orthorhombic perovskite structure. The results of the infrared (IR) studies on orthorhombic and tetragonal phases of some of these compounds provide evidence for the oxygen rearrangement on going from the orthorhombic to the tetragonal phase.

Ba2RESbO6 (RE = Nd, Eu and Dy); Characterization and Potential Use as Substrate for Superconducting YBCO Films

1997 ◽  
Vol 11 (20) ◽  
pp. 889-897 ◽  
Author(s):  
P. R. S. Wariar ◽  
J. Kurian ◽  
P. K. Sajith ◽  
T. G. N. Babu ◽  
J. Koshy
Keyword(s):  
Single Phase ◽  
Detrimental Effect ◽  
Diffraction Measurement ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Complex Perovskite ◽  
X Ray ◽  
Dielectric Constant And Loss ◽  
Zero Resistance ◽  
Potential Use

Perovskite compounds of the general formula, Ba2RESbO6 (where RE = Nd, Eu and Dy) were sintered as single phase materials by standard solid state techniques. These compounds are found to be isostructural and to have a complex perovskite structure as observed by powder X-ray diffraction measurement. No chemical reaction between YBa2Cu3O 7-δ and Ba2RESbO6 compounds, was observed even under severe heat treatment at 950°C, and the addition of Ba2RESbO6 up to 20 vol% in YBa2Cu3O 7-δ, shows no detrimental effect on the superconducting properties of YBa2Cu3O 7-δ. The dielectric constant and loss factor values of sintered specimens, are in a range suitable for their use as substrates for microwave applications. Thick films of YBCO fabricated on highly polished Ba2RESbO6 specimens, gave a superconducting zero resistance transition T c(o) of 92 K, with a critical current density, J c of 2×104 A/cm2 at 77 K.

ANALYSIS OF FLUCTUATION CONDUCTIVITY OF GRANULAR Gd1-xPrxBa2Cu3O7-δ SUPERCONDUCTOR

2010 ◽  
Vol 24 (24) ◽  
pp. 2465-2475 ◽  
Author(s):  
CRISTIANO SANTOS LOPES ◽  
LINCOLN BRUM DE LEITE GUSMÃO PINHEIRO ◽  
MARCELO DOS SANTOS ◽  
ALCIONE ROBERTO JURELO ◽  
ROSÂNGELA MENEGOTTO COSTA ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Electrical Transport ◽  
Single Phase ◽  
Transition Width ◽  
X Ray Diffraction ◽  
Solid State Reaction Technique ◽  
Fluctuation Conductivity ◽  
X Ray ◽  
Zero Resistance ◽  
Resistance State

Single phase polycrystalline Gd 1-x Pr x Ba 2 Cu 3 O 7-δ (0 ≤ x ≤ 0.10) samples have been prepared by standard solid state reaction technique and characterized by SEM, X-ray diffraction and electrical transport experiments. The samples were granular and homogeneous. It was observed that the critical temperature decreases and that the transition width increases with increasing Pr doping. Systematic measurements of fluctuation conductivity are reported. Special attention is taken above the critical temperature, where Gaussian and critical regimes are observed. Below the critical temperature, on approaching the zero resistance state, our results show a power-law behavior consistent with a phase transition from a paracoherent to a coherent state of the granular array.

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