中国物理B ›› 2009, Vol. 18 ›› Issue (9): 4000-4006.doi: 10.1088/1674-1056/18/9/064

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Doping dependent metal to insulator transition in the (Bi,Pb)-2212 system: The evolution of structural and electronic properties with europium substitution

ShabnaRazia, Sarun Pallian Murikoli, VinuSurendran, SyamaprasadUpendran   

  1. National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum, India-695019
  • 收稿日期:2008-09-19 修回日期:2009-04-02 出版日期:2009-09-20 发布日期:2009-09-20
  • 基金资助:
    Project supported by Kerala State Council for Science, Technology and Environment, Council of Scientific and Industrial Research and the University Grants Commission of India.

Doping dependent metal to insulator transition in the (Bi,Pb)-2212 system: The evolution of structural and electronic properties with europium substitution

Shabna Razia, Sarun Pallian Murikoli, Vinu Surendran, and Syamaprasad Upendran†   

  1. National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum, India-695019
  • Received:2008-09-19 Revised:2009-04-02 Online:2009-09-20 Published:2009-09-20
  • Supported by:
    Project supported by Kerala State Council for Science, Technology and Environment, Council of Scientific and Industrial Research and the University Grants Commission of India.

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摘要： The present work investigates the effect of europium substitution on the (Bi, Pb)-2212 system in the concentration range 0.5 ≤ x ≤ 1.0. Phase analysis and lattice parameter calculations on the powder diffraction data and the elemental analysis of EDX show that the Eu atoms are successfully substituted into the (Bi, Pb)-2212 system. Resistivity measurements (64--300~K) reveal that the system exhibits superconductivity at x ≤ 0.5 and semiconductivity at x > 0.5. With the complete suppression of superconductivity which is known to be a quasi-two dimensional phenomenon in these materials, a metal to insulator transition takes place at x=0.6 and the predominant conduction mechanism is found to be variable range hopping between localized states, resulting in macroscopic semiconducting behaviour. The results of electrical and structural properties of the doped (Bi, Pb)-2212 compounds suggest that the decrease of charge carrier concentration and the induced structural disorder are the more effective and dominant mechanisms in the origin of the metal to insulator transition and suppression of superconductivity due to Eu substitution at its Sr site.

Abstract: The present work investigates the effect of europium substitution on the (Bi, Pb)-2212 system in the concentration range 0.5 ≤ x ≤ 1.0. Phase analysis and lattice parameter calculations on the powder diffraction data and the elemental analysis of EDX show that the Eu atoms are successfully substituted into the (Bi, Pb)-2212 system. Resistivity measurements (64--300 K) reveal that the system exhibits superconductivity at x ≤ 0.5 and semiconductivity at x > 0.5. With the complete suppression of superconductivity which is known to be a quasi-two dimensional phenomenon in these materials, a metal to insulator transition takes place at x=0.6 and the predominant conduction mechanism is found to be variable range hopping between localized states, resulting in macroscopic semiconducting behaviour. The results of electrical and structural properties of the doped (Bi, Pb)-2212 compounds suggest that the decrease of charge carrier concentration and the induced structural disorder are the more effective and dominant mechanisms in the origin of the metal to insulator transition and suppression of superconductivity due to Eu substitution at its Sr site.

Key words: (Bi, Pb)-2212 superconductor, metal to insulator transition, variable range hopping, electrical properties

中图分类号:  (Effects of crystal defects, doping and substitution)

  • 74.62.Dh
61.66.Fn (Inorganic compounds) 71.30.+h (Metal-insulator transitions and other electronic transitions) 74.25.Jb (Electronic structure (photoemission, etc.))