Title :
Niobium induced metal-superconductor to metal-insulator transition in the YBCO system
Author :
Semchinova, O.K. ; Grekchov, I.V. ; Delimova, L.A. ; Linijchuck, I.A.
Author_Institution :
Inst. fur Halbleitertechnol. und Werkstoffe der Elektrotech., Hannover Univ., Germany
fDate :
6/1/1995 12:00:00 AM
Abstract :
In this work a novel high-T/sub c/ compound of the form YBa/sub 2/Cu/sub 3(1-x)/Nb/sub x/O/sub 7/ as been synthesized and investigated for a broad range of Nb contents O0.21 corresponding to a no-superconducting state, the conduction mechanism is adequately described through the variable-range-hopping (VRH) model. Comparison of experimental data with theory provides an estimation of both, carrier localization length and density of states at the Fermi energy.<>
Keywords :
Fermi level; barium compounds; electrical resistivity; electron density; electronic density of states; high-temperature superconductors; hopping conduction; localised states; metal-insulator transition; superconducting transition temperature; yttrium compounds; 90 K; CuO; Fermi energy; Y/sub 2/BaCuO/sub 5/; YBa/sub 2/(CuNb)/sub 3/O/sub 7/; YBa/sub 2/Cu/sub 3(1-x)/Nb/sub x/O/sub 7/; YBa/sub 2/NbO/sub 6/; carrier localization length; critical temperature; density of states; dielectric inclusions; dilute superconducting grains; high temperature superconductivity; metal-insulator transition; resistivity; variable-range-hopping model; Conductivity; Doping; Granular superconductors; High temperature superconductors; Metal-insulator structures; Niobium; Superconducting materials; Superconducting transition temperature; X-ray diffraction; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
