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Al-doping Effects on the Superconductivity of MgB2

Author: MaJinYuan
Tutor: SunAiMin
School: Northwest Normal University
Course: Condensed Matter Physics
Keywords: MgB2 Doping Superconductivity The Topological index Valence electron orbit energy topological index
CLC: O511
Type: Master's thesis
Year: 2010
Downloads: 33
Quote: 0
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Abstract


The thesis is divided into two parts content. The first part introduces the development of superconductivity , the basic nature of the superconductivity , BCS theory and its main conclusions . 2001 superconducting transition temperatures as high as 39K metal the compound of MgB 2 < / sub> discovery has aroused widespread concern in the world of physics , materials and industry , our brief analysis of MgB < / sub> superconducting properties of the superconducting mechanism , and a few years to study the status and application prospects . Known doping is the study of the variation of the performance of the superconducting material , commonly used methods to find a new superconducting material . Mainly to explain the adoption of improved solid phase reaction sintering process a series of Mg 1 - x Al x B 2 ( 0.00-0.15 ) super conductivity materials , and their structures, the transition temperature and the superconducting characteristics was studied . Found that with the increase in the lattice parameter of Al incorporation and critical transition temperature has a decreasing trend . The combined XRD analysis , found that most of the Al atoms replace Mg atoms . This article analyzes the causes of this phenomenon results show that may be induced defects and samples of the Al atom of Al the distribution the unevenness formed MgAlB 4 < / sub> and the reaction of Al 2 < / sub> O 3 , have had an impact on superconductivity . The second section describes the predictive ability of the molecular topological index theory and molecular topological index materials research , practical value and some typical topological index . The topological properties of molecules and atoms is inherent geometric properties of molecules and atoms , it can reflect the structure of molecules and atoms important information that will help us to predict the nature of the substance . And the relationship between the 0 -order index 2 doped system through the study of MgB critical transition temperature and electronegativity topological index of valence electron orbit energy topological index found that the high transition temperature of the material in the best the corresponding doping within 2.9034-2.9509 and 3.9218-3.8613 respectively within . This change by experimental means MgBcTmFmV 0 F 0 < / sup > V 0 < / sup> F 0 < / sup > V2 system doped ingredients to ensure the selection and concentration of the dopant doping size to ensure that the transition temperature increases for experimentalists will explore better doping MgB 2 the system superconducting material research provides a draw .

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CLC: > Mathematical sciences and chemical > Physics > Low Temperature Physics > Superconductivity
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