A5080345974- Physics of Superconductivity and Magnetism
- Superconductivity in MgB2 and Alloys
- Iron-based superconductors research
- Magnetic and transport properties of perovskites and related materials
- Electronic and Structural Properties of Oxides
- Advanced Condensed Matter Physics
- ZnO doping and properties
- Acoustic Wave Resonator Technologies
- Magnesium Alloys: Properties and Applications
- Semiconductor materials and devices
- Molecular Junctions and Nanostructures
- Superconducting Materials and Applications
- Electrochemical Analysis and Applications
- Water Treatment and Disinfection
- Silicon Carbide Semiconductor Technologies
- Corrosion Behavior and Inhibition
- Copper Interconnects and Reliability
- Thermal Expansion and Ionic Conductivity
- Advancements in Solid Oxide Fuel Cells
- HVDC Systems and Fault Protection
- Electrochemical sensors and biosensors
- Chemical and Physical Properties of Materials
- Microwave Dielectric Ceramics Synthesis
- Molecular Sensors and Ion Detection
- Boron and Carbon Nanomaterials Research
Tianjin University
2024-2025
Yanbian University
2024
Anyang Normal University
2013
Shandong University
2006-2007
Oak Ridge National Laboratory
2001-2006
University of Houston
2000-2005
Institute of Physics
1997
Superconducting MgB2 films with Tc=38.6 K were prepared using a precursor-deposition, ex situ postprocessing approach. Precursor of boron, ∼0.5 μm thick, deposited onto Al2O3 (102) substrates by electron-beam evaporation; postanneal at 890 °C in the presence bulk and Mg metal produced highly crystalline films. X-ray diffraction indicated that exhibit some degree c-axis alignment, but are randomly oriented plane. Transport current measurements superconducting properties show high values...
Superconducting magnesium diboride films with Tc0∼24 K and sharp transition ∼1 were prepared on Si by pulsed-laser deposition from stoichiometric MgB2 target. Contrary to previous reports, anneals at 630 °C a background of 2×10−4 Ar/4%H2 performed without the requirement Mg vapor or cap layer. This integration superconducting film may thus prove enabling in superconductor-semiconductor device applications. Images surface morphology cross-section profiles scanning electron microscopy show...
Ultrathin YBa2Cu3O7−δ (YBCO) films down to two unit cells thick have been prepared on LaAlO3 (LAO) and SrTiO3 (STO) substrates for the study of substrate-induced strain effects critical transition temperature (Tc). The YBCO LAO has a higher Tc than that STO very thin films, this difference increases with reduction film thickness. X-ray diffraction experiments reveal compressive exists in a–b plane LAO, while tensile occurs STO. different stresses these account difference.
We have investigated the temperature and magnetic field dependence of Hall coefficient two well-characterized superconducting ${\mathrm{MgB}}_{2}$ films ${(T}_{c0}=38.0\mathrm{K})$ in both normal states. Our results show that normal-state ${R}_{H}$ is positive increases with decreasing temperature, independent applied (to 8 T). find ${R}_{H}^{\ensuremath{-}1}\ensuremath{\propto}T(40--300\mathrm{K})$ $\mathrm{cot}{\ensuremath{\theta}}_{H}\ensuremath{\propto}{T}^{2}(100--300\mathrm{K}).$ As...
We have studied the structure of superconducting gap in MgB2 thin films by means point-contact spectroscopy using a gold tip. The were produced depositing pure boron on sapphire substrate, e-beam evaporation, followed reaction with magnesium vapour. Tc 38.6 +- 0.3 K and resistivity about 20 microOhm cm at 40 K. spectra prove directly existence multi-valued order parameter MgB2, two distinct values gap, DELTA1=2.3+-0.3 meV DELTA2=6.2+-0.7 4.2 Analysis terms Blonder-Tinkham-Klapwijk model...
A new method for continuous compositional-spread (CCS) thin-film fabrication based on pulsed-laser deposition (PLD) is introduced. This approach a translation of the substrate heater and synchronized firing excimer laser, with occurring through slit-shaped aperture. Alloying achieved during film growth (possible at elevated temperature) by repeated sequential sub-monolayer amounts. Our overcomes serious shortcomings in previous in-situ implementations CCS sputtering or PLD, particular...
An MgB2 thin film deposition technology is the first critical step in development of superconducting electronics utilizing 39 K superconductor. It turned out to be a challenging task due volatility Mg and phase stability MgB2, low sticking coefficients at elevated temperatures, reactivity with oxygen. A brief overview current techniques provided here from thermodynamic perspective, an emphasis on very successful technique for high quality situ epitaxial films, hybrid physical–chemical vapour...
Electrochemical DNA (E-DNA) based biosensors have been shown to be a promising alternative mass- and fluorescence-based sensors for the specific detection of oligonucleotide sequences. MicroRNAs (miRNAs) are believed important cancer diagnosis prognosis serving as reliable molecular biomarkers. In this work, we reported label-free electrochemical sensor miRNAs on difference in structure RNA DNA. Specifically, were captured by pre-immobilized probes electrode recognized electrochemically...
In this paper we present the results of measurements microwave surface impedance a powder sample and two films MgB2. The has Tc = 39 K have 29 38 K. These samples show different temperature dependences field penetration depth. Over period six months, film with degraded to 35 We compare on all data obtained elsewhere discuss implications as far is possible at stage.
The development of YBa2Cu3O7−δ (YBCO)-based coated conductors for electric power applications will require electrical and thermal stabilization the high-temperature superconducting (HTS) coating. In addition, nonmagnetic tape substrates are an important factor in order to reduce ferromagnetic hysteresis energy loss ac applications. We report progress toward a conductive buffer layer architecture on biaxially textured Cu tapes electrically couple HTS underlying metal substrate. A protective...
The effect of water exposure on MgB2 is studied by submerging an 800 nm thick film into de-ionized at room temperature for 1 h, 4 10 and 15 analysing the resulting material using scanning electron microscopy resistance versus measurements. It clearly observed that Tconset these films (obtained ex-situ reaction e-beam evaporated boron layer) remains unchanged throughout this process, indicating least a portion sample retains its original bulk-like properties. data consistent with...
The microwave power and frequency dependence of the surface resistance MgB2 films powder samples were studied. Sample quality is relatively easy to identify by breakdown in ω2 law for poor-quality at all temperatures. performance 10 GHz 21 K was compared directly with that high-quality YBCO films. found be approximately three times higher low showed an onset nonlinearity fields ten lower than film. It clear are not yet optimized applications.
Electrical and thermal stability of high-temperature superconducting (HTS) wires∕tapes are essential in applications involving efficient production, distribution, storage electrical energy. We have developed a conductive buffer layer structure composed bilayer La0.7Sr0.3MnO3∕Ir on textured Ni–W alloy metal tape to functionally shunt the HTS underlying substrate. The key feature is Ir layer, which serves as barrier both inward diffusion oxygen outward substrate cations during fabrication....
Single buffer layer of LaMnO/sub 3/ (LMO) has been epitaxially grown on biaxially textured Ni and Ni-alloy substrates by sputter deposition. The property characterizations revealed that LMO buffers can serve both as a chemical well structural for YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films. Epitaxial YBCO films using pulsed laser deposition (PLD) have self-field critical current densities (J/sub c/) exceeding 1 /spl times/ 10/sup 6/ A/cm/sup 2/ at 77 K. present results demonstrated...