Abstract： Lead-free piezoelectric ceramics of （1 - x） Bi0.5K0.5TiO3-BaTiO3 （BKT-BT） were fabricated by the solid state reaction method with normal sintering. The influence of BT addition on the crystal structure,...Abstract： Lead-free piezoelectric ceramics of （1 - x） Bi0.5K0.5TiO3-BaTiO3 （BKT-BT） were fabricated by the solid state reaction method with normal sintering. The influence of BT addition on the crystal structure, phase transition and dielectric properties was investigated. The crystal structure and ferroelectric phase transition were studied by XRD （X-ray diffraction） and dielectric measurements. The complete solid solution of BKT-BT was observed for all compositions. In XRD results, all compositions showed a single phase perovskite structure with tetragonal symmetry at room temperature. With increasing BT content, the separation between diffraction peaks corresponded to increasing tetragonality. The phase transition temperature of ferroelectric tetragonal-paraelectric cubic （Tc） decreased with increasing BT content. As the amount of BT concentration increased, the ceramic became denser, and almost no porosity was finally obtained.展开更多
We report the discovery and characterization of a novel 112-type iron pnictide EuFeAs2, with La-doping induced superconductivity in a series of Eu1- xLaxFeAs2. The polycrystalline samples were synthesized through soli...We report the discovery and characterization of a novel 112-type iron pnictide EuFeAs2, with La-doping induced superconductivity in a series of Eu1- xLaxFeAs2. The polycrystalline samples were synthesized through solid state reaction method only within a very narrow temperature window around 1073 K. Small single crystals were also grown from a flux method with the size about 100μm. The crystal structure was identified by single crystal X-ray diffraction analysis as a monoclinic structure with space group of P2 1/m. From resistivity and magnetic susceptibility measurements, we found that the parent compound EuFeAs2 shows distinct anomalies probably due to the Fe2＋ related antiferromagnetic/structural phase transition near 110K and the Eu2＋ related antiferromagnetic phase transition near 40K. La-doping suppressed both phase transitions to lower temperatures and induced superconducting transitions with a Tc - 11 K for Eu0.85La0.15FeAs2.展开更多
文摘Abstract： Lead-free piezoelectric ceramics of （1 - x） Bi0.5K0.5TiO3-BaTiO3 （BKT-BT） were fabricated by the solid state reaction method with normal sintering. The influence of BT addition on the crystal structure, phase transition and dielectric properties was investigated. The crystal structure and ferroelectric phase transition were studied by XRD （X-ray diffraction） and dielectric measurements. The complete solid solution of BKT-BT was observed for all compositions. In XRD results, all compositions showed a single phase perovskite structure with tetragonal symmetry at room temperature. With increasing BT content, the separation between diffraction peaks corresponded to increasing tetragonality. The phase transition temperature of ferroelectric tetragonal-paraelectric cubic （Tc） decreased with increasing BT content. As the amount of BT concentration increased, the ceramic became denser, and almost no porosity was finally obtained.
基金the financial supports from the National Natural Science Foundation of China (11474339)the National Basic Research Program of China (973 Program, 2016YFA0300301, 2010CB923000 and 2011CBA00100)the Youth Innovation Promotion Association of the Chinese Academy of Sciences
文摘We report the discovery and characterization of a novel 112-type iron pnictide EuFeAs2, with La-doping induced superconductivity in a series of Eu1- xLaxFeAs2. The polycrystalline samples were synthesized through solid state reaction method only within a very narrow temperature window around 1073 K. Small single crystals were also grown from a flux method with the size about 100μm. The crystal structure was identified by single crystal X-ray diffraction analysis as a monoclinic structure with space group of P2 1/m. From resistivity and magnetic susceptibility measurements, we found that the parent compound EuFeAs2 shows distinct anomalies probably due to the Fe2＋ related antiferromagnetic/structural phase transition near 110K and the Eu2＋ related antiferromagnetic phase transition near 40K. La-doping suppressed both phase transitions to lower temperatures and induced superconducting transitions with a Tc - 11 K for Eu0.85La0.15FeAs2.
