COMPOSITION DEPENDENCE OF SUPERCONDUCTIVITY AND CRYSTAL STRUCTURE IN La(Ba1−xCax)2Cu3O7−y SYSTEM

1989 ◽  
Vol 03 (04) ◽  
pp. 307-311 ◽  
Author(s):  
N. CAO ◽  
J.Q. ZHENG ◽  
X.Y. SHAO ◽  
X.S. CHEN ◽  
W.Y. GUAN
Keyword(s):  
Crystal Structure ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Composition Dependence ◽  
Superconducting Transition ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
Zero Resistance

The composition dependence of superconductivity and crystal structure in La ( Ba 1−x Ca x)2 Cu 3 O 7−y system was determined by the resistivity measurements and X-ray diffraction analysis. The superconducting transition temperature is raised with the increase of Ca content till x=0.6, at which the zero resistance temperature of the sample is 81.5 K. In the meanwhile, the crystal structure of the sample changed from tetragonal (x=0) to orthorhombic structure (x=0.2, 0.4, 0.6). With further increase of Ca content, the superconductivity decrease for the sample of x=0.8 with mixed phases including the orthorhombic oxygen-deficient perovskite-like (ODP) structure and no superconducting transition is found at 4.2 K for the sample of x=1 without the ODP structure. A possible explanation of these experimental results is given.

Superconducting YBa2Cu3O7−x fibers from the thermoplastic gel method

1989 ◽  
Vol 4 (4) ◽  
pp. 787-794 ◽  
Author(s):  
Fusaoki Uchikawa ◽  
John D. Mackenzie
Keyword(s):  
Transition Temperature ◽  
Surface Area ◽  
Superconducting Transition Temperature ◽  
Organic Content ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Shrinkage Ratio ◽  
X Ray ◽  
Zero Resistance ◽  
Solution Route

The successful fabrication of ceramic superconducting YBa2Cu3O7−x fibers has been investigated. A new method was proposed for synthesis of the fibers through a solution route. The thermoplastic gels were synthesized using Y, Ba, Cu, ethoxides, and diethylenetriamine. The fibers were drawn from the reheated gels. The fibers were characterized by x-ray diffraction, SEM, and shrinkage ratio measurements. The fired and then annealed fiber is shown to have a superconducting transition temperature of 91 K (onset) and zero resistance temperature of 84 K. With regard to the fired fibers, it is found that the surface area increased and superconducting transition temperature decreased with increasing organic content in the initial gel. The usefulness of this method is shown and the structure of the synthesized gel is discussed.

Oxygen Stoichiometry and Superconductivity in Ho1Ba2Cu3O7−x

1987 ◽  
Vol 99 ◽  
Author(s):  
B. C. Sales ◽  
Y. C. Kim ◽  
J. R. Thompson ◽  
D. K. Christen ◽  
L. A. Boatner ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Transition Temperature ◽  
High Resolution ◽  
Oxygen Vacancies ◽  
Oxygen Stoichiometry ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
General Shape ◽  
X Ray ◽  
Lattice Constants

ABSTRACTThe effects of varying oxygen content on the superconducting transition temperature Tc, resistivity, and crystal structure of HoBa2Cu3O7−x (0 < x < 1) have been investigated. The variation of Tc wltn 8 is very similar to that previously reported by several authors for YBa2Cu3O7−x [1,2]. In particular a plateau in the Tc vs x curve is observed for values of x between 0.3 and 0.4 witfi the value of Tc,(10 % onset measured magnetically) remaining relatively constant at about 55 K. The width of the superconducting transition, as measured both resistively and magnetically, is substantially narrower for x= 0.35 + 0.05 than for slightly larger or smaller values of x. High resolution powder x-ray diffraction analysis was used to measure the lattice constants of both the orthorhombic and tetragonal phases as x was varied. With increasing x the temperature coefficient of the resistivity changed from positive (metallic) for x ≤0.2 to negative (semiconducting) for x ≥, 0.3. Since the general shape of the Tc vs x curve was unaffected by the complete substitution of magnetic Ho for Y, these results suggest an ordering of the oxygen vacancies in the a-b plane and the existence of an ordered compound with a Tc of 55 K.

Effects of (La0.67Ca0.33MnO3)x (x= 0.0, 0.8, 1.0) Additions on the Structural and Superconducting Transition Temperature of YBa2Cu3O7-δ System

2014 ◽  
Vol 895 ◽  
pp. 75-78
Author(s):  
B.N. Fadilah ◽  
Shaari Abdul Halim ◽  
Mansor Hashim ◽  
R.S.N. Ain ◽  
H.A.N.N. Amalina ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Xrd Analysis ◽  
Magnetic Behaviour ◽  
Ybco Superconductor ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
Space Group

The effect addition of manganites compound on the superconducting properties of YBCO was investigated through X-Ray diffraction (XRD), resistance-temperature (R-T) measurement, AC Susceptometer, and Scanning Electron Microscope (SEM). Samples with addition of (La0.67Ca0.33MnO3)x(LCMO) (x= 0.0, 0.8, 1.0) in YBa2Cu3O7-δ(YBCO) superconductor were prepared via solid state method. Addition of LCMO in YBCO superconductor changed the properties of samples. XRD analysis showed the addition of LCMO (0.8 wt% - 1.0 wt%) formed three new peaks of LCMO. The crystal structure is orthorhombic with space group Pmmm for pure Y123 but after addition 0.8 wt% and addition 1.0 wt% of LCMO the crystal structure was changed to tetragonal and space group P4/mmm. The temperature dependent of electrical resistance showed the samples were metallic above the transition temperature even though after addition. TheTc-onsuperconducting transition temperature decreased from 86 K to 84 K while theTc-offdecreased from 76 K to 70 K. Diamagnetic onset transition temperature,Tc-on(dia)decreased from 90.2 K to 89.8 K. This suppression was due to the magnetic behaviour of the LCMO addition. Morphology observation showed that the grain size and grains boundary are decreased while the porosity was increased as the addition of LCMOincreases.

STUDY OF THE DEPENDENCE OF HIGH Tc ON VARIOUS SINTERING TEMPERATURES FOR Bi-Pb-Sr-Ca-Cu-O SUPERCONDUCTORS

1991 ◽  
Vol 05 (24n25) ◽  
pp. 1635-1638
Author(s):  
S.M. M.R. NAQVI ◽  
A.A. QIDWAI ◽  
S.M. ZIA-UL-HAQUE ◽  
FIROZ AHMAD ◽  
S.D.H. RIZVI ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Liquid Nitrogen ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
Resistivity Measurements ◽  
Zero Resistance

Bi1.7-Pb0.3-Sr2-Ca2-Cu3-Ox superconducting samples were prepared at 855°C, 862 C, 870 C, and 882 C sintering temperatures respectively. All samples were sintered for 120 hours. The samples were then quenched in liquid nitrogen. The electrical resistivity measurements showed that the samples sintered at 870° C had the best Tc. For these samples the Tc onset was around 120 K and the zero resistance was obtained at 108 K. X-ray diffraction studies showed that the samples were multiphased.

Evolution of crystal structure of dual layered molecular conductor (ET)4ZnBr4(C6H4Cl2) with temperature

CrystEngComm ◽  
2021 ◽  
Author(s):  
Gennady V. Shilov ◽  
Elena I. Zhilyaeva ◽  
Sergey M. Aldoshin ◽  
Alexandra M Flakina ◽  
Rustem B. Lyubovskii ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electrical Resistivity ◽  
Single Crystal ◽  
Room Temperature ◽  
Organic Conductor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
Molecular Conductor ◽  
Abrupt Changes

Electrical resistivity measurements of a dual layered organic conductor (ET)4ZnBr4(1,2-C6H4Cl2) above room temperature show abrupt changes in resistivity at 320 K. Single-crystal X-ray diffraction studies in the 100-350 K range...

Effects of Electron Beam on Structure and Physical Properties of Natural Colorless Topaz

2015 ◽  
Vol 1125 ◽  
pp. 60-63
Author(s):  
Chutharat Paikaew ◽  
Juthamas Inthanont ◽  
Adisak Punyanut ◽  
Ekachai Hoonnivathana ◽  
Pichet Limsuwan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Beam ◽  
Physical Properties ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spin Resonance ◽  
Function Group ◽  
And Function ◽  
Beam Dose

The purpose of this research was to investigate physical properties, configuration and color of topaz. Topazes were irradiated with electron beam linear accelerator at different dose from 40 to 180 MGy. The color of topaz was analyzed by UV-vis and it was shown that the color of topaz was becoming strong color with increased electron beam dose. Crystal structure and function group of topaz were characterized by X- ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The results showed that the topaz has orthorhombic structure and no other crystalline. After irradiated, topaz released OH indicating higher crystallinity of topaz and this was confirmed with the results of electron spin resonance (ESR). Electron beam dose response of topaz was investigated. ESR results showed that the Al3+ ion was substituted in Si4+ site and Ti3+ impurity in Al4+ site and this result corresponds to the results of FTIR. The experiment result indicated that electron beam could be making defect on crystal structure and color enhancement of topaz.

Structure and properties of solid solutions in the Mg-Al-B system

Open Physics ◽  
2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Ludmila Sevastyanova ◽  
Olga Gulish ◽  
Vladimir Stupnikov ◽  
Vladimir Genchel ◽  
Oleg Kravchenko ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Unit Cell ◽  
Superconducting Transition ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Resistivity Measurements ◽  
Ceramic Synthesis

AbstractCompounds with the general formula Mg1−x AlxB2 were obtained by two-step ceramic synthesis. All compounds were characterized by X-ray diffraction, NMR spectroscopy, and by four point probe resistivity measurements in various magnetic fields method. The diborides unit cell parameters were determined as a function of the Al mole fraction. With the vaues of x up to 0.40 (where x is the composition of the stock prepared for sintering), the unit cell parameters of Mg1−x AlxB2 are similar to those of pure MgB2 and the superconducting transition temperature was lowered. For stock compositions of 0:25 ≤ x ≤ 0:60, the products contain a superstructure, also superconducting phase, which becomes the only product at x = 0:50, and at x > 0:60 this phase is replaced by AlB2-based solid solutions.

Synthesis and Properties of YBaSrCu3O6.9 Prepared from Soluble Precursors

1988 ◽  
Vol 121 ◽  
Author(s):  
Paul J. Nigrey ◽  
J. F. Kwak ◽  
E. L. Venturini ◽  
M. O. Eatough ◽  
R. J. Baughman
Keyword(s):  
Solid Solution ◽  
Solution Chemistry ◽  
X Ray Diffraction ◽  
Oxygen Annealing ◽  
X Ray ◽  
Resistivity Measurements ◽  
Superconducting Ceramics ◽  
Magnetization Data ◽  
Zero Resistance ◽  
Superconducting Onset Temperature

ABSTRACTSolution chemistry routes have been used to prepare single-phased superconducting ceramics of YBaSrCu3O6.9 (1113). Resistivity measurements on air annealed samples showed a superconducting onset temperature of 85 K with zero resistance at 78 K which improves to 81 K upon oxygen annealing. Magnetization data show ca. 78% flux exclusion at 5 K for 1113. X-ray diffraction experiments revealed that an orthorhombic to tetragonal transition occurs near 590°C when 1113 was heated in air. This work has demonstrated that such techniques can be utilized to prepare solid solution material with properties similar to those observed in YBa2Cu3Ox (123).

Properties and Structures of Copper Rich Y-Ba-Cu-O Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
A. J. Drehman ◽  
J. A. Horrigan ◽  
M. W. Dumais
Keyword(s):  
Transition Temperature ◽  
Grain Boundaries ◽  
Superconducting Transition Temperature ◽  
Superconducting Transition ◽  
Zero Resistance ◽  
Resultant Material

ABSTRACTCopper rich Y-Ba-Cu-O samples were prepared by reacting and sintering powders. The resultant material is composed of YBa2Cu3Oy and CuO. Proper processing results in a 85% dense, well interconnected material with a superconducting transition temperature of 92K. Zero resistance is observed even though a quarter of the volume is the CuO phase. This is because the CuO phase is in the form of isolated grains and not at the grain boundaries of the superconducting matrix.

scholarly journals Influence of Processing Conditions on Crystal Structure of Bi6Fe2Ti3O18 Ceramics

2016 ◽  
Vol 61 (2) ◽  
pp. 881-886 ◽  
Author(s):  
A. Lisińska-Czekaj ◽  
M. Lubina ◽  
D. Czekaj ◽  
M. Rerak ◽  
B. Garbarz-Glos ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ambient Air ◽  
Processing Conditions ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
Reaction Route ◽  
X Ray ◽  
Number Of Layers ◽  
Solid State Reaction Route ◽  
Diffraction Patterns

Abstract Aim of the present research was to apply a solid state reaction route to fabricate Aurivillius-type ceramics described with the formula Bi6Fe2Ti3O18 (BFTO) and reveal the influence of processing conditions on its crystal structure. Pressureless sintering in ambient air was employed and the sintering temperatures were 850 and 1080 °C. It was found that the fabricated BFTO ceramics were multiphase ones. They consisted of two Bim+1Fem-3Ti3O3m+3 phases, namely the phase with m=5 (i.e. the stoichiometric phase) and m=4 (i.e. the phase with a reduced number of layers in the slab). Detailed X-ray diffraction patterns analysis showed that both phases adopted the same orthorhombic structure described with Fmm2 (42) space group. The ratio of weight fractions of the constituent phases (m=5): (m=4) was ~30:70.

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