Correction to: Enhanced critical current density of ex situ MgB2 via control of Mg assisted sintering

Journal of Materials Science: Materials in Electronics -     

Combination of Ag Substrate Decoration with Introduction of?BaZrO3 Nano-Inclusions for?Enhancing Critical Current Density of?YBa2Cu3O7 Films

The combination of two methods: Ag substrate decoration and introduction of BZO nano-inclusions has been used in a pulsed laser deposition (PLD) method to increase the critical density (J _c ) of YBCO films. The films were deposited on single crystal SrTiO₃ (STO) substrates decorated with various architecture of Ag nano-dots. We have studied the diameter and density of Ag nano-dots and their influence on J _c of BZO-added YBCO films. We found that 15 laser pulses on the Ag target gives an optimum result in increasing J _c in comparison with BZO-doped YBCO films of the same thickness in self-field and low applied magnetic fields. A higher number of laser pulses on the Ag target led to increasing critical current density in high applied magnetic fields only (above 2 T). We have studied films of the thickness from 0.4 ??m to 3.8 ??m and found that the highest J _c at all applied fields investigated is achieved for a 1.2 ??m thick film. The transmission electron microscopy clearly shows BZO nano-rods that provide strong c-axis pinning centres in the films.     

Improved critical current densities in thick YBa2Cu3O7 − δ multilayer films interspaced with non-superconducting YBa2Cu3Ox nanodots

We have fabricated and studied quasi-multilayered thick YBa₂Cu₃O_7 − δ (YBCO) films composed of several YBCO layers interspaced with quasi-layers of non-superconducting YBa₂Cu₃O_x nanodots, grown by Pulsed Laser Deposition on SrTiO₃ (100) substrates. Magnetization J_c(B) at 77.3 K for these thick films showed significant improvement as compared to pure YBa₂Cu₃O_7 − δ films of same or even smaller thickness. A high J_c(B) in our quite thick films (1 μm to 6 μm) provides a very high total critical current per centimetre of the film width, I_c − w. Critical current as high as 830 A per cm width in self field and 77.3 K was achieved in 5 μm thick quasi-multilayer film with non-superconducting YBa₂Cu₃O_x nanodots. Frequency-dependent susceptibility measurements showed also an increase in the pinning potential. The angular dependence of I_c − w at 86.5 K, in 3 T shows a clear indication of anisotropic pinning centres aligned along the c-direction.     

Improvement of Pinning Force and Critical Current Density in Thick YBa 2 Cu 3 O 7−δ Films Grown on SrTiO 3 Substrates Decorated with LaNiO 3 Nanodots

We have investigated by DC magnetization measurements and frequency-dependent AC susceptibility the critical current density (J _c), pinning force (F _p) and pinning potential in thick (1.3–1.6 μm) YBa₂Cu₃O_7−δ (YBCO) films grown by Pulsed Laser Deposition on SrTiO₃ substrates decorated with LaNiO₃ nanodots deposited by a few (5–15) laser pulses, in comparison with those of a 1 μm thick YBCO reference sample. Experiments show that the highest improvement of superconducting properties was achieved for films grown on substrates decorated with 10 laser pulses on the LaNiO₃ target, which have, at 77.3 K, a J _c of 40–125% higher than in pure YBCO in fields between 1 and 2 T, and F _p increased by 40%. These results could be important for further improvement of current-carrying capability of coated conductors for in-field power applications.     

Growth and characterization of La5/8Sr3/8MnO3 thin films prepared by pulsed laser deposition on different substrates

Colossal magnetoresistance La_5/8Sr_3/8MnO₃ (LSMO) thin films were directly grown on MgO(100), Si(100) wafer and glass substrates by pulsed laser deposition technique. The films were characterized using X-ray diffraction (XRD), field emission-scanning electron microscope and atomic force microscopy (AFM). The electrical and magnetic properties of the films are studied. From the XRD patterns, the films are found to be polycrystalline single-phases. The surface appears porous and cauliflower-like morphology for all LSMO films. From AFM images, the LSMO films deposited on glass substrate were presented smooth morphologies of the top surfaces as comparing with the films were deposited on Si(100) and MgO(100). The highest magnetoresistance (MR) value obtained was ?17.21 % for LSMO/MgO film followed by ?15.65 % for LSMO/Si and ?14.60 % for LSMO/Cg films at 80 K in a 1T magnetic field. Phase transition temperature (T_P) is 224 K for LSMO/MgO, 200 K for LSMO/Si and above room temperature for films deposited on glass substrates. The films exhibit ferromagnetic transition at a temperature (T_C) around 363 K for LSMO/MgO, 307 K for LSMO/Si and 352 K for LSMO/Cg thin film. T_C such as 363 and 352 K are the high T_C that has ever been reported for LSMO films deposited on MgO substrate with high lattice mismatch parameter and glass substrates with amorphous nature.     

AC Losses in YBCO-Added Bi<Subscript>1.6</Subscript>Pb<Subscript>0.4</Subscript>Sr<Subscript>2</Subscript>Ca<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript><Emphasis Type="Italic">δ</Emphasis></Subscript> Superconductors

The effect of YBCO adding on the superconducting of BPSCCO system with nominal starting composition of (Bi_1.6Pb_0.4Sr₂Ca₂Cu₃O _δ )_1?x(YBCO) _x with x = 0.00?0.10 was studied. The preparation methods used to prepare the samples are the conventional solid-state techniques. From the XRD data, it is observed that the percentage of the Bi-2223 phase increases and Bi-2212 decreases for addition x = 0.02–0.04, respectively. The effect of YBCO addition on the BPSCCO system also has been investigated in term of AC susceptibility study. We have studied the various applied field dependence of the AC susceptibility in polycrystalline samples. The AC susceptibility measurements in the range 0.05 to 2.00 Oe show that as the applied fields increases, the intergranular AC loss peaks move to lower temperature, and also height decreases and width increases. The effect of YBCO addition for the intergranular critical current J _cm, and the presence of weak links that coupled the superconducting grains were defined.     

Structural,electrical and magnetic properties of polycrystalline La0.67(Ca1−x Sr x )0.33MnO3 manganites

Polycrystalline La_0.67(Ca_1?x Sr _x )_0.33MnO₃ with different substitution level of strontium element, were synthesized via solid state reaction. Structure of samples was characterized by X-ray diffraction (XRD). XRD patterns reveal that La_0.67Ca_0.33MnO₃ exhibits orthorhombic structure with space group Pnma. Phase transitions from orthorhombic to rhombohedral take place as Ca ions were gradually substituted by Sr ions. The XRD data were further analyzed by Rietveld refinement technique. The data show that Mn–O–Mn bond angle increases as x increases. Microstructures obtained from SEM show that substitution of Sr ions has demoted the grain growth and densification process during sintering. The substitution of Sr ions has greatly influenced the hopping integral of electron via double exchange interaction, thus affecting the electrical properties and magnetic properties as well. The resistivity decreases and the metal–insulator transition temperature (T _p ) shifts to higher temperature as x increases. The magnetoresistance (MR) effect gradually decreases and MR peak shifts to higher temperature as x increases. The magnetization measured at room temperature is found to be increasing as x increases.     

Improved Critical Current Densities in YBa2Cu3O7?�� Multilayer Films Interspaced with Palladium Nano-dots

Power applications of superconducting coated conductors in high magnetic fields require thick films with high critical current density J _c and strong artificial pinning centers. Here, we report on the artificial pinning centers induced in YBCO quasi-multilayer films interspaced with palladium (Pd) nano-dots. Quasi-multilayered (QM) YBa₂Cu₃O_7??? (YBCO) films composed of YBCO layers interspaced with quasi-layers of palladium nano-dots were grown by pulsed laser deposition on SrTiO₃(100) substrates. DC magnetization and frequency-dependent measurements showed high J _c comparable with best YBCO films in thin quasi-multilayers and significant improvement of J _c in thick quasi-multilayers. TEM study shows regions of planar defects, stacking faults, and pore formations suitable for immobilizing vortices. These defects significantly contribute to the pinning of magnetic flux and increase critical current in the films.     

Enhanced critical current density of ex situ MgB2 via control of Mg assisted sintering

Journal of Materials Science: Materials in Electronics - In this work,&nbsp;ex situ&nbsp;MgB2&nbsp;was mixed with 0.5&nbsp;mol of Mg and sintered. The sintering conditions were...