通过先制备一种纳米尺寸的GdF_3作为GdFeAsO_(1-x)F_x样品中F的反应原料,在相对较低的温度(1120℃)下成功制备出一系列GdFeAsO_(1-x)F_x(x=0,0.05,0.1,0.15,0.2,0.25)多晶样品.X射线衍射结果表明,超导样品属四方ZrCuSiAs-type结构,晶格参数随着掺F量的增加而减小.扫描电子显微镜测试结果表明,样品具有片层状晶体形貌特征.当掺F量x=0.1时,样品表现出超导电性,超导转变温度为22K,随着掺F量的增多,超导转变温度升高.和其他制备方法相比,这种制备方法更有利于F的掺入,而且可有效减少样品中杂质相的含量.
Preparation of F-doped GdFeAsO_(1-x)Fx samples has been developed using GdF_3 with nanometer scale as the source of fluorine. Polycrystalline samples of GdFeAsO_(1-x)F_x(x = 0, 0. 05, 0.1, 0. 15, 0. 2, 0. 25) have been successfully synthesized using the present method. According to the X-ray diffraction patterns, all of the samples possess a tetragonal ZrCuSiAs-type structure and the lattice parameters decreased with the increasing doping level. The layered crystal structure has been observed in the scanning electronic Microscope (SEM) images. Superconductivity emerges when x = 0.1 with a transition temperature of 22K and it is definitely enhanced with the increasing F-doping level. Compared with other methods, this process is more effective to introduce F into GdFeAsO system as well as reduce the content of the impurities in the samples.
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