Quenched Fe moment in the collapsed tetragonal phase of Ca_(1-x)Pr_x Fe_2As_2

We report 75As NMR studies on single crystals of rare-earth doped iron pnictide superconductor Ca1-xPrxFe2As2 . In both cases of x = 0.075, 0.15, a large increase of νq upon cooling is consistent with the tetragonal-collapsed tetragonal structure transition. A sharp drop of the Knight shift is also seen just below the structure transition, which suggests the quenching of Fe local magnetism, and therefore offers important understanding of the collapsed tetragonal phase. At even low temperatures, the 1/75T1 is enhanced and forms a peak at T ≈ 25 K, which may be caused by the magnetic ordering of the Pr3+ moments or spin dynamics of mobile domain walls.     

硫化亚铜/四针状氧化锌晶须纳米复合材料的制备及其光催化性能(英文)

在聚乙烯吡咯烷酮的辅助下,采用多元醇法制备了不同铜/锌摩尔比的硫化亚铜/四针状氧化锌晶须纳米复合材料,并利用X射线衍射、场发射扫描电镜、X射线光电子能谱和紫外-可见漫反射光谱对样品进行了表征.结果表明,在紫外光照射下,样品对甲基橙的光降解效率优于纯ZnO晶须.在铜/锌摩尔比低于4%时,样品的光催化性能随着铜/锌摩尔比增加而增加,但随着铜/锌摩尔比的继续增加,样品的光催化性能下降.此外,还采用周期实验来评价催化剂的稳定性.结果表明,该催化剂具有优异的光催化稳定性.