The Effects of Transition Metal Substitutions for Copper in the Bi-Sr-Ca-Cu-O Superconducting System

1989 ◽  
Vol 169 ◽  
Author(s):  
J.C. Bennett ◽  
F.W. Boswell ◽  
J.M. Corbett ◽  
S. Kohara ◽  
F.S. Razavi
Keyword(s):  
Transition Metal ◽  
Single Phase ◽  
Superconducting Phase ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Slight Effect ◽  
X Ray ◽  
Edx Analysis

AbstractThe effects of transition metal dopants on superconductivity in samples of nominal composition Bi2CaSr2(Cu1-xMx)208+δ with M = Co, Fe, Ni and Zn have been investigated for 0 ≤ x ≤ 1. Co and Fe additions progressively suppress the ? of the doped material and result in semiconducting behaviour for x ≤ 0.2. In the ranges 0 ≤ x ≤ .07 and near x = 1.0, x-ray diffraction reveals the samples are essentially single phase but are multiphase otherwise. Ni and Zn dopants have only a very slight effect on Tc; however, EDX analysis reveals these elements are not significantly Incorporated into the superconducting phase.

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 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.

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.

VARIATION OF Tc IN SINGLE PHASE Bi4Sr3Ca3Cu4O16−x SYSTEM

1990 ◽  
Vol 04 (22) ◽  
pp. 1385-1391 ◽  
Author(s):  
M. NASIR KHAN ◽  
FARID A. KHWAJA
Keyword(s):  
High Temperature ◽  
Critical Temperature ◽  
Solid State ◽  
Single Phase ◽  
High Temperature Superconductor ◽  
Interlayer Spacing ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
X Ray

The variation of critical temperature Tc in a single-phased ceramic high temperature superconductor Bi 4 Sr 3 Ca 3 Cu 4 O y is studied using techniques like X-ray diffraction, magnetic and electrical measurements. Samples of Bi-Sr-Ca-CuO having nominal composition 4334 are synthesized by solid state reaction using appropriate amounts of Bi 2O3, SrCO 3, CaCO 3 and CuO powders. It has been shown that the Tc in this material can be raised from 98 K in the fast quenched sample to 120 K in the furnace-cooled one. The higher values of Tc in furnace cooled specimens as compared with the Tc in quenched samples have been attributed to the variation in the interlayer spacing in these compounds. It is concluded that electron density and hence the attractive interaction between pairs are increased due to shortening of the interlayer spacing in the furnace-cooled sample, leading to an increase of its Tc.

VARIATION OF Tc IN SINGLE PHASE Bi2Sr2Ca1Cu2O8−x SYSTEM

1991 ◽  
Vol 05 (24n25) ◽  
pp. 1645-1653
Author(s):  
M. NASIR KHAN ◽  
F.A. KHWAJA ◽  
RAANA FARID
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Electron Density ◽  
Solid State Reaction ◽  
Single Phase ◽  
High Temperature Superconductor ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Layer Spacing ◽  
X Ray

The variation of Tc in a single-phase high temperature superconductor Bi 2 Sr 2 Ca 1 Cu 2 O 8−x is studied using techniques like X-ray diffraction, magnetic and electric measurements. The samples of Bi-Sr-Ca-Cu-O (with nominal composition 2212) are synthesized by solid state reaction using appropriate amounts of Bi 2 O 3, SrCO 3, CaCO 3 and CuO powders. The Tc is found to vary from 92 K to 115 K in the quenched samples. These changes in the value of Tc have been related to the changes in the inter-layer spacing. It is concluded that an increase in the electron density due to shortening of the inter-layer increases the attractive interaction between pairs and is thus responsible for the high Tc in these superconductors.

Synthesis and Dielectric Properties of Ba(Ti,Y)O3 Solid Solutions to Ba3Ti2YO8.5-BaTiO3 Composites

2011 ◽  
Vol 194-196 ◽  
pp. 109-112
Author(s):  
Min Huang ◽  
Yun Wu Wang
Keyword(s):  
Single Phase ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Microstructure Observation ◽  
Ceramic Samples ◽  
Scanning Electron

Ceramic samples with the nominal composition (1-x) BaTiO3 + x Ba3Ti2YO8.5 (x = 0 - 0.4) were prepared by the solid-state reaction method. The X-ray diffraction (XRD) analysis and the lattice parameters determination indicate that the samples with x≤ 0.16 exhibit a single phase cubic perovskite structure. When x > 0.16, the system is of biphasic composites, which consist of Ba(Ti0.911Y0.089)O3 and Ba3Ti2YO8.5. The microstructure observation by Scanning Electron Microscopy (SEM) supports the XRD result. For the biphasic composites, the dielectric constant follows the Lichtenecker relation in a wide temperature range.

SUPERCONDUCTIVITY IN Y-Ba-Cu(Cr)-O SYSTEM

1987 ◽  
Vol 01 (02) ◽  
pp. 281-284
Author(s):  
Z. Xianyu ◽  
R.J. Li ◽  
Q.H. Zhao ◽  
L.Q. Liu ◽  
Q.T. Wang ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Structural Analysis ◽  
Single Phase ◽  
Hexagonal Phase ◽  
Superconducting Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Superconductor

We report the superconductor of Y-Ba-Cu-O system, with Tci= 100K , Tc=95K , Tcf=94.1K and Δ Tc=1K . The structural analysis by X-ray diffraction shows that single phase superconductor has order-disorder transformation around 220K and phase transformation takes place in the multiphase sample in the range of (123–173K). This indicates that the phase transformation related to the high Tci. With the substitution of Cr for Cu, with Cu:Cr=2:1 we have also obtained the superconductor with Tci=95.5 , Tc=91K , Tcf=86.3K and Tc=1K X-ray structural analysis shows that the major superconducting phase of this system is hexagonal phase.

SUPERCONDUCTIVITY IN Bi-Sr-Ca-Mg-Cu-OXIDE

1991 ◽  
Vol 05 (11) ◽  
pp. 771-777 ◽  
Author(s):  
A.Y. KHAN ◽  
M. MOHAMMAD ◽  
M. SHAHNAZ ◽  
S.K. HASNAIN
Keyword(s):  
Magnetic Susceptibility ◽  
Electrical Resistance ◽  
Meissner Effect ◽  
Superconducting Phase ◽  
Partial Substitution ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Minor Phase ◽  
X Ray ◽  
A Minor

A Mg -substituted material with nominal composition Bi 2 Sr 2 Ca 3 Mg 2 Cu 6 O x, prepared by partial substitution of Ca by isovalent Mg in the 2256 composition of Bi-Sr-Ca-Cu-O , has been studied by the measurements of electrical resistance, magnetic susceptibility and X-ray diffraction pattern. Results show the existence of a superconducting phase with onset T c at 112.5±1 K along with a minor phase with onset T c =88 K . The material retained superconducting characteristics (Meissner effect and T c onset ) even after a period of six months.

Synthesis of YBa2Cu3O7−x by chemical precursors

1991 ◽  
Vol 6 (1) ◽  
pp. 11-17 ◽  
Author(s):  
D. E. Peterson ◽  
K. A. Kubat-Martin ◽  
T. G. George ◽  
T. G. Zocco ◽  
J. D. Thompson
Keyword(s):  
Single Phase ◽  
High Temperature Superconductor ◽  
Superconducting Phase ◽  
Synthesis Methods ◽  
Scanning Electron Microscopy Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopy Data ◽  
Microscopy Data ◽  
Synthesis Approach

An alternative synthetic route for obtaining bulk forms of the high temperature superconductor YBa2Cu3O7−x has been investigated. The approach is based on first preparing the phases Y2Cu2O5 and BaCuO2, followed by a single sintering of an appropriate mixture of these intermediate compounds to produce the superconducting phase. The resulting materials are largely single-phase as shown by x-ray diffraction, and have densities as high as 86% of the theoretical value, and superconducting onset temperatures of 93 K with magnetic shielding factors ranging from 0.85 to 1.02 (±0.05). Metallography and scanning electron microscopy data were also obtained on the best (high Tc, high shielding factors) of the samples. This synthesis approach is believed to be simpler, more reproducible, and has the potential of producing better materials than previously used bulk synthesis methods.

Raman And Fluorescence Spectra Observed in Laser Microprobe Measurements of Several Compositions in the Ln-Ba-Cu-O System

1990 ◽  
Vol 48 (2) ◽  
pp. 278-279
Author(s):  
Edgar S. Etz ◽  
Thomas D. Schroeder ◽  
Winnie Wong-Ng
Keyword(s):  
Fluorescence Spectra ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Raman Microprobe ◽  
Methods Of Synthesis ◽  
Compositional Homogeneity ◽  
Processing Techniques

We are investigating by Raman microprobe measurements the superconducting and related phases in the LnBa2Cu3O7-x (for x=0 to 1) system where yttrium has been replaced by several of the lanthanide (Ln = Nd,Sm,Eu,Ho,Er) elements. The aim is to relate the observed optical spectra (Raman and fluorescence) to the compositional and structural properties of these solids as part of comprehensive materials characterization. The results are correlated with the methods of synthesis, the processing techniques of these materials, and their superconducting properties. Of relevance is the substitutional chemistry of these isostructural systems, the differences in the spectra, and their microanalytical usefulness for the detection of impurity phases, and the assessment of compositional homogeneity. The Raman spectra of most of these compounds are well understood from accounts in the literature.The materials examined here are mostly ceramic powders prepared by conventional solid state reaction techniques. The bulk samples are of nominally single-phase composition as determined by x-ray diffraction.

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