We find that the superconductivity in the thin films of the formerly believed non-superconducting parent compound FeTe is accompanied by an emergence of second order with a correlation length of 742 nm and 258 nm at 1...We find that the superconductivity in the thin films of the formerly believed non-superconducting parent compound FeTe is accompanied by an emergence of second order with a correlation length of 742 nm and 258 nm at 10 K and 300 K, respectively. The structural phase transition found in iron pnictide superconductors, in non-superconducting FeTe bulk samples, and in FeSe superconducting thin films is not observed in the superconducting FeTe thin films. The interplay between superconductivity and long range order may suggest the crucial role of competition between electronic localization and itinerancy which leads to strong quantum fluctuations in the FeTe system.展开更多
Piezoelectric ceramics (Na0.5Bi0.5) （0.92）Ba0.08TiO3 +x%MnCO3（BNBT-Mn, x=0CD*21.6, mass fraction） were synthesized by conventional solid state reaction. The results show that when the addition of MnCO3 is 0CD*2 1....Piezoelectric ceramics (Na0.5Bi0.5) （0.92）Ba0.08TiO3 +x%MnCO3（BNBT-Mn, x=0CD*21.6, mass fraction） were synthesized by conventional solid state reaction. The results show that when the addition of MnCO3 is 0CD*2 1.4%, BNBT-Mn ceramics exhibit a single-phase perovskite structure. With the increase of content of MnCO3, piezoelectric constant and electromechanical coupling factor increase rapidly when x is lower than 0.3. Then they both decrease when x is in the range of 0.3 and 1.6. When x=0.3, piezoelectric constant and electromechanical coupling factor reach the maximum value of 160pC/N and 58.5% respectively, which can improve the temperature stability of BNBT-Mn.展开更多
Thin film bulk acoustic resonators are fabricated by using silicon bulk micromachining technology, which are constructed mainly from aluminium nitride （AlN） piezoelectric films. The results of x-ray diffraction, sca...Thin film bulk acoustic resonators are fabricated by using silicon bulk micromachining technology, which are constructed mainly from aluminium nitride （AlN） piezoelectric films. The results of x-ray diffraction, scanning electron microscopy and atomic force microscopy show that the AlN films exhibit highly c-axis orientation with good surface morphology. The resonators with the AlN films possessed a reflection coefficient -10.6 dB at the resonant frequency 2.537 GHz, an effective electromechanical coupling coefficient 3.75%, series quality 101.8, and parallel quality 79. 7.展开更多
Tt-phase electron-doped superconductor Pr1-xLaCexCuO4-δ（PLCCO） thin films are successfully prepared on SrTiOs （100） substrates by using the dc magnetron sputtering method. It is found that the films each have a h...Tt-phase electron-doped superconductor Pr1-xLaCexCuO4-δ（PLCCO） thin films are successfully prepared on SrTiOs （100） substrates by using the dc magnetron sputtering method. It is found that the films each have a highly oriented structure along the c-axis. For optimally doped films with x ≈ 0.10, the superconducting transition temperature Tc is 25.5 K, which is similar to that of a single crystal. The quadratic temperature dependence of the resistivity is observed when T 〉 To, which can be attributed to the two-dimensional Fermi liquid behaviour. Besides, the optimal conditions for preparing the T1-phase PLCCO thin films are also discussed in detail.展开更多
基金Project supported by the National Basic Research Program of China(Grant Nos.2006CB921107 and 2010CB630704)the National Natural Science Foundation of China(Grant No.10774165)
文摘We find that the superconductivity in the thin films of the formerly believed non-superconducting parent compound FeTe is accompanied by an emergence of second order with a correlation length of 742 nm and 258 nm at 10 K and 300 K, respectively. The structural phase transition found in iron pnictide superconductors, in non-superconducting FeTe bulk samples, and in FeSe superconducting thin films is not observed in the superconducting FeTe thin films. The interplay between superconductivity and long range order may suggest the crucial role of competition between electronic localization and itinerancy which leads to strong quantum fluctuations in the FeTe system.
文摘Piezoelectric ceramics (Na0.5Bi0.5) （0.92）Ba0.08TiO3 +x%MnCO3（BNBT-Mn, x=0CD*21.6, mass fraction） were synthesized by conventional solid state reaction. The results show that when the addition of MnCO3 is 0CD*2 1.4%, BNBT-Mn ceramics exhibit a single-phase perovskite structure. With the increase of content of MnCO3, piezoelectric constant and electromechanical coupling factor increase rapidly when x is lower than 0.3. Then they both decrease when x is in the range of 0.3 and 1.6. When x=0.3, piezoelectric constant and electromechanical coupling factor reach the maximum value of 160pC/N and 58.5% respectively, which can improve the temperature stability of BNBT-Mn.
基金Supported by the National Natural Science Foundation of China under Grant No 50572026, and the Wuhan Key Technology Project under Grant No 20061002073.
文摘Thin film bulk acoustic resonators are fabricated by using silicon bulk micromachining technology, which are constructed mainly from aluminium nitride （AlN） piezoelectric films. The results of x-ray diffraction, scanning electron microscopy and atomic force microscopy show that the AlN films exhibit highly c-axis orientation with good surface morphology. The resonators with the AlN films possessed a reflection coefficient -10.6 dB at the resonant frequency 2.537 GHz, an effective electromechanical coupling coefficient 3.75%, series quality 101.8, and parallel quality 79. 7.
基金supported by the State Key Program for Basic Research of China(Grant No 2004CB619004-1)the National Natural Science Foundation of China(Grant No 10474121)
文摘Tt-phase electron-doped superconductor Pr1-xLaCexCuO4-δ（PLCCO） thin films are successfully prepared on SrTiOs （100） substrates by using the dc magnetron sputtering method. It is found that the films each have a highly oriented structure along the c-axis. For optimally doped films with x ≈ 0.10, the superconducting transition temperature Tc is 25.5 K, which is similar to that of a single crystal. The quadratic temperature dependence of the resistivity is observed when T 〉 To, which can be attributed to the two-dimensional Fermi liquid behaviour. Besides, the optimal conditions for preparing the T1-phase PLCCO thin films are also discussed in detail.
