Preparation Of Iron-based Superconducting Film And Phase Analysis Of Germanium-based Rare Earth Alloys

(I)Part I of this thesis prepared FeTe alloy though conventional solid-state reaction. The vacuum sintered alloy with nominal composition of FeTe was analyzed using powder X-ray diffraction and refined with Rietveld method. It is shown that FeTe alloy crystallizes a tetragonal structure with space group of P/4nmm and its lattice constant is a=3.8214(3)A, c=6.2875(3) A, Z=2. Fe at2a and2c positions and Te at2c positions. No superconducting transition was observed in relevant electromagnetic measurements. FeTe films prepared by pulsed laser deposition showed superconducting transition with starting transition temperature Tc,onset of13.2K and Tc,0of9.8K. We believe the emergence of superconducting transition originates from the two dimensional characteristic and stress-induced variation of structure of thin films. In the end, suggestions were made for further research.(Ⅱ)Part Ⅱ of this thesis focused on vacuum arc preparation of Ge-based rare earth alloys of1:2and1:3system. Phase composition and its variation with composition were studied through powder X-ray method. Indexing results of unknown orthorhombic phases Ain GdGe3-xMnx were:M(22)=10, F(22)=8, a=8.01A, b=5.69A, c=4.02A and for unknown orthorhombic phase B in TbGe3-xMnx were:M(23)=17, F(23)=13, a=7.99A, b=4.01A, c=3.26A. At last, suggestions on subsequent work were made.