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1.
Stuart C. Wimbush Dominic Walsh Simon R. Hall 《Physica C: Superconductivity and its Applications》2010,470(7-8):373-377
We have recently demonstrated that through a sol–gel route, superconductor crystallization in the presence of simple biopolymers results in a drastic alteration of morphology, producing technologically useful nanowires and porous architectures. Morphological control is of the utmost importance to bulk high-temperature superconductors, as grain boundaries act as weak links in limiting the achievable critical current density (Jc). Here we show that, as expected, the incorporation of nanoparticulate barium zirconate (BaZrO3) species into a biopolymer-mediated synthetic protocol for YBa2Cu3O7?δ (Y123) leads to a significantly improved in-field Jc compared to that observed in a sample without BaZrO3 additions. To ameliorate degradation of the BaZrO3 species in this protocol, we demonstrate that by drawing the precursor sol into fibers, a microtape architecture is able to be formed, leading to lengthy, anisotropic structures having enhanced Jc through the retention of the BaZrO3 species. 相似文献
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Self-injection length in La0.7Ca0.3MnO3-YBa2Cu3O7-δ ferromagnet-superconductor multilayer thin films
We have carried out extensive studies on the self-injection problem in barrierless heterojunctions between La0.7Ca0.3MnO3 (LCMO) and YBa2Cu3O7-δ (YBCO) thin films. The heterojunctions were formed in situ by sequentially growing LCMO and YBCO films on 〈100〉 LaAlO3 (LAO) substrate using a pulsed laser deposition (PLD) system. YBCO micro-bridges with 64 μm width were patterned both on
the LAO (control) and LCMO side of the substrate. Critical current, I
c, was measured at 77 K on both the control side as well as the LCMO side for different YBCO film thickness. It was observed
that while the control side showed a J
c of ∼ 2 × 106 A/cm2, the LCMO side showed about half the value for the same thickness (1800 ?). The difference in J
c indicates that a certain thickness of YBCO has become ‘effectively’ normal due to self-injection. From the measurement of
J
c at two different thicknesses (1800 ? and 1500 ?) of YBCO films both on the LAO as well as the LCMO side, the value of self-injection
length (at 77 K) was estimated to be ∼ 900 ?. To the authors’ best knowledge, this is the first time that self-injection length
has been quantified. A control experiment carried out with LaNiO3 deposited by PLD on YBCO did not show any evidence of self-injection. 相似文献
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CoFe2O4-BaTiO3 composites were prepared using conventional ceramic double sintering process with various compositions. Presence of two phases
in the composites was confirmed using X-ray diffraction. The dc resistivity and thermoemf as a function of temperature in
the temperature range 300 K to 600 K were measured. Variation of dielectric constant (ɛ′) with frequency in the range 100 Hz to 1 MHz and also with temperature at a fixed frequency of 1 kHz was studied. The ac
conductivity was derived from dielectric constant (ɛ′) and loss tangent (tan δ). The nature of conduction is discussed on the basis of small polaron hopping model. The static value of magnetoelectric
conversion factor has been studied as a function of magnetic field. 相似文献
6.
A Gurtu P K Malhotra I S Mittra P M Sood SC Gupta VK Gupta GL Kaul LK Mangotra Y Prakash NK Rao ML Sharma 《Pramana》1974,3(5):311-322
This is a continuation of our earlier investigation (Gurtuet al 1974Phys. Lett. 50 B 391) on multiparticle production in proton-nucleus collisions based on an exposure of emulsion stack to 200 GeV/c beam at the NAL. It is found that the ratioR em = 〈n s〉/〈n ch〉, where 〈n ch〉 is the charged particle multiplicity in pp-collisions, increases slowly from about 1 at 10 GeV/c to 1·6 at 68 GeV/c and attains a constant value of 1·71 ± 0·04 in the region 200 to 8000 GeV/c. Furthermore,R em = 1·71 implies an effectiveA-dependence ofR A =A 0.18,i.e., a very weak dependence. Predictions ofR em on various models are discussed and compared with the emulsion data. Data seem to favour models of hadron-nucleon collisions in which production of particles takes place through adouble step mechanism,e.g., diffractive excitation, hydrodynamical and energy flux cascade as opposed to models which envisage instantaneous production. 相似文献
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Periodic superconducting, porous self-supporting monoliths were synthesized using cuttlebone as a morphological template; this produced a lightweight, structurally stable superconductor with a greatly improved critical current density. 相似文献
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The magnetic susceptibility and the electrical resistivity of n-type BaTi1-xNbxO3 have been measured over a wide temperature range. It is found that, for 0相似文献
9.
Munshi G Mustafa Sudhir Raniwala T Awes B Rai RS Bhalerao JG Contreras RV Gavai SK Ghosh P Jaikumar GC Mishra AP Mishra H Mishra B Mohanty J Nayak J-Y Ollitrault SC Phatak L Ramello R Ray PK Sahu AM Srivastava DK Srivastava VK Tiwari 《Pramana》2006,67(5):961-981
This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and
work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported. 相似文献
10.
G.H. Cao P. Simon W. Skrotzki S.C. Wimbush B. Holzapfel 《Applied Physics A: Materials Science & Processing》2005,81(3):583-585
A thin film of the superconductor YNi2B2C deposited on an MgO(001) substrate by pulsed laser deposition has been investigated by transmission electron microscopy (TEM). Plan-view TEM analyses show that the YNi2B2C film consists of isolated rectangular grains distributed within a second phase. This phase was identified as the monoclinic phase Y2Ni15B6 with lattice parameters a=1.422 nm,b=1.067 nm,c=0.958 nm and β=95°. Additionally, the cubic phase Y2O3 with lattice constant a=1.06 nm was identified within the film. PACS 74.70.Dd; 74.78.Db; 68.37.Lp; 68.55.-a 相似文献