The Effect Of Sn And Ca Doping On YBCO Respectively Under Different Experiment Conditions

During a long period of time in which researchers have carried on research continually on the superconductor YBCO, various adulteration about it has been made in order to improve its superconducting properties. These adulterations mainly included element doing（replacement）and compound doping. In this first mode,different elements caused different consequences for YBCO. Therefore we can formulate a hypothesis as follows: Suppose all adulterations are made by the same element, can we find the best condition and quantity if we change the sintering temperature of the working process（must not surpass or under certain temperature）,which means trace of change under a certain amount of condition. Based on this hypothesis,this thesis take“ the effect of Sn and Ca doping on YBCO respectively under different e_xperiment conditions ”as its title. The main points of it can be listed as follows:1.A series of superconductor samples that the SnO2 doping on YBCO were prepared using solid-state reaction method under different temperature. The phase formation, Micro-structure,crystal structure and superconducting transition temper ature（Tc） were studied by means of XRD, SEM techniques and resistivity measure ements.The results indicted that the different sintering temperatures affect Sn4+to form. The intensity of Y-123 diffraction peak decreases obviously an any other SeconDary phase e_xits with increase of sintering temperature. This paper analyzes intrinsic association e_xisting between lattice structure and superconductivity. The SEM results reveal the presence of second-phase particle and surface topography depend upon the temperature as well.2.A series of Y_1-x Ca_xBa₂Cu3O_7-δ（_x=0⁰.08） superconductor samples were prepared by solid-state reaction method. The morphology and structure of samples are characterized by X-ray diffraction. With the increase of substituting quantity, the structure of sample has not trend from the orthogonal phase to tetragonal phase to tetragonal phase gradually. We adopted the X- ray diffraction on the sample lattice structure is analyzed The results show that 0.06 is the best doping rat four terminal method. The result indicates that superconducting transition temperature has a tendency of holistic dropping with the increase of Ca substituting quantity. And we do the theoretical analysis of e_xperimental. We also analyze intrinsic association e_xisting between lattice structure and superconductivity.