材料期刊网

一种具有双光子活性的新型吡啶盐的合成、表征及性质

周虹屏 , 郝扶影 , 张居舟 , 赵祖志 , 李东梅 , 吴杰颖 , 田玉鹏 , Hoong-Kun Fun

应用化学 doi:10.3969/j.issn.1000-0518.2005.06.007

合成了1种新的D-π-A结构的吡啶盐,通过红外、元素分析、热重分析、单晶X射线衍射对化合物的结构进行了表征. 研究了它的荧光光谱,用1 064 nm皮秒脉冲激光研究了它的三阶非线性光学特性. 结果表明,该吡啶盐的双光子吸收系数β=0.104 7 cm/GW,双光子吸收截面σ=3.247 3×10-46 cm 4 · s · photon-1,当泵浦能量达到1.677 mJ时,上转换效率达到1.9%.

关键词: D-π-A吡啶盐 , 三阶非线性光学特性 , 单晶X射线衍射 , Z扫描

Giant magnetoresistance in Co-Cu-Ni granular ribbons

Journal of Physics-Condensed Matter

We have systematically investigated the structural, magnetic and transport properties of as-quenched and annealed Co20NixCu80-x (0 less than or equal to x less than or equal to 20) granular alloys prepared by melt spinning. The microstructure of granular ribbons of Co-Ni-Cu shows a matrix in which nanoparticles of Co-Ni are well distributed, very different from that of granular ribbons of Ca-Cu in which fun-grown Co microparticles are embedded in a Cu matrix. The phase segregation in the Co-Ni-Cu granular ribbons is not a pure nucleation and growth process as in the Co-Cu granular ribbons, but also not purely due to spinodal decomposition. In contrast to the ribbons with high Ni content, the low-Ni-content ribbons show an increase in magnetoresistance (Delta R/R congruent to 6.2% at 300 K for Co20Ni5Cu75, which is larger than in as-quenched and annealed Co-Cu ribbons.

关键词: magnetic-properties;films;alloys