Synthesis of ZnO：Dy Nanopowder and Photoluminescence of Dy^3＋ in ZnO

A type of dysprosium-doped ZnO （ZnO：Dy） nanopowder was synthesized by high temperature calcinations. XRD was used to analyze the structure. Photoluminescence spectra were used to study the optical characteristic. PL of ZnO：Dy shows two different spectra which are broad band resulted from the defect of Dy in ZnO and sharp lines from the 4f→4f transition of isolated Dy^3 ＋ luminescence center. The emission and excitation spectra depend on the excitation wavelength and the concentration of Dy^3＋ . The broad bands with peaks at 600 and 760 nm are attributed to the recombination from an electron of the defect Dy in ZnO to a hole in VB.

F掺杂对铁基超导体SmO_(1-x)F_δFeAs制备和性能的影响(英文)

研究了F掺杂对铁基超导体SmO0.7F0.3FeAs的制备和性能的影响。利用二次固相反应在1120℃保温40h制备出超导临界转变温度(Tc)为56.5K的SmO0.7F0.3FeAs超导体样品,其临界电流密度Jc为2.4×105A/cm2(10K,0T)。研究发现,SmO1-xFxFeAs样品的Tc受F含量的强烈影响,晶格参数的变化也是诱导SmO1-xFxFeAs超导体的Tc变化的原因之一。在此基础上详细研究了F元素过掺杂对铁基超导体SmO1-xFδFeAs(δ>x)制备参数和性能的影响。F元素过量时,在不降低SmO1-xFδFeAs超导性能的情况下,F元素过掺杂可以一定程度地降低样品制备时的热处理温度和极大地缩短热处理时间。1100℃时保温20h制备的SmO0.7F0.35FeAs和SmO0.7F0.4FeAs样品的Tc分别为56和55K;其临界电流密度Jc分别为1.9×105和1.7×105A/cm2(10K,0T)。