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The communication range of magnetic-induction (MI) technology in extreme environments such as underwater or underground is limited by the dipole-like attenuation behavior of the magnetic field as well as the eddy current induced loss in conductive media, and therefore a highly sensitive receiver is generally required. In this work, we propose the use of a highly sensitive superconducting quantum interference device (SQUID) in MI communication and try to provide a comprehensive investigation on developing a SQUID-based receiver for practical MI applications. A portable receiver scheme integrating a SQUID sensor and a coil-based flux transformer was proposed. The high sensitivity and long-range communication capability of the proposed receiver was experimentally demonstrated by spectroscopic measurements and reception experiments on a receiver prototype. Based on the experimental demonstrations, the sensitivity optimization of the proposed scheme was further investigated by simulation studies, which suggest that a communication distance exceeding 100 m and a channel capacity of ∼20 kb/s in underwater environment could be achieved based upon the optimization of the developed prototype. The results presented in this work have highlighted the potential of deploying SQUID sensors for long-range MI applications in extreme environments.

The use of lead-free ceramic film materials with positive temperature coefficient of resistivity (PTCR) is widespread in temperature heaters and sensors in micro-electromechanical systems. In this research, the out of plane transport properties of the BiFeO3 (BFO) films have been studied. Surprisingly, PTCR was found in the BFO ceramic films due to the strongly correlated interaction between the multiferroic material BFO and the superconductor YBCO perovskite oxides. To our knowledge, this is the first report on the PTCR effect of BFO films. The BFO/YBCO interface and the bulk conductivity of BFO are important for the PTCR effect, as they make it possible to compare the transport properties of Au/BFO/YBCO- and YBCO/BFO/YBCO-type structures. PTCR was observed in Au/BFO/YBCO at a bias voltage of more than 2 V, but not in the YBCO/BFO/YBCO, even with a 40 V bias voltage. PTCR was found after BFO breakdown of a YBCO/BFO/YBCO capacitor. This indicated that the conductivity of BFO is critical for PTCR. The dependence of PTCR on the superconducting transition temperature illustrates that a cooper-pair can be injected into BFO. Our work presents a method by which to produce a lead-free ceramic film material with PTCR.

Studying a unified nonlinear response function near the vortex solid liquid transition and make microscopic analysis of the superconducting-normal state (S-N) resistive transition. This equation combined with the Maxwell equation may provide a useful tool for applied superconductivity design.

We experimentally studied a passive mode-locked square-wave fiber laser with net-normal dispersion by using a nonlinear amplifying loop mirror. The output pulse width of the square-wave pulse (SWP) can be extended with the increasing of the pump power as well as single pulse energy. The SWP can be amplified without shape distortion when the mode-locked laser is injected into an erbium-ytterbium codoped fiber amplifier. Then, by inputting the amplified SWPs into a single mode fiber (SMF), a supercontinuum (SC) can be observed with the spectral range of about 1550 to 1850 nm. Broader and flatter SC with the 20-dB spectral range of about 1550 to 1950 nm can also be generated using a segment of dispersion-shifted fiber instead of SMF. [ABSTRACT FROM AUTHOR]

The crystal structure stability as well as electric conductance of (Sr/Ca)2CuO2Cl2compound with K2NiF4 structure was Investigated up to 31 GPa using diamond anvil technique. It seems that (Sr/Ca)2CuO2Cl2 is quite stable under pressure but with obvious anisotropic compressibility. The equation of state (EOS) obtained shows relative large bulk modulus. [ABSTRACT FROM AUTHOR]

Analyzes the properties of high-quality c-axis Nd[sub 1+x]Ba[sub 2-x]Cu[sub 3]O[sub 7-d] (Nd123) thin films produced by the laser ablation method. Resistivity of deposited films; Composition of the films under varied deposition conditions; Effect of laser fluence on the thin films.

Practical applications of the MgB2 prepared by the in situ method are usually limited because of the pores formed by the volatility of Mg. In order to improve the performance of MgB2 bulks, MgB2 bulks were fabricated through an in situ synthesis method with composites of B powder, Mg powder, and 10–100 wt% Mg(BH4)2 powder. The superconducting properties and grains structure of these MgB2 bulks were investigated, such as onset superconducting transition temperature (Tc), critical current density (Jc), porosity, resistivity (ρ), and grain connectivity. For the MgB2 bulk prepared from 80 wt% Mg(BH4)2 powder added composites, the Jc (1 T) value at 5 K was 4.1 × 105 A cm−2 and the onset Tc value was 37.5 K. Moreover, the microstructure of these MgB2 bulks was also analyzed using scanning electron microscope (SEM). The MgB2 bulk with less pores can be prepared with moderate Mg(BH4)2 powder added composite as precursor. The composites also provide raw materials for preparing high-quality in situ MgB2 superconducting wires. [ABSTRACT FROM AUTHOR]