Neutron structural studies of the superconducting YBa<sub>2</sub>(Cu<sub>1-x</sub>V<sub>x</sub>)<sub>3</sub>O<sub>7- delta </sub> system at x=0.04 and 0.06
U S Joshi; A Sequeira; H Rajagopal; R G Kulkarni; U S Joshi; Dept. of Phys., Saurashtra Univ., Rajkot, India; A Sequeira; Dept. of Phys., Saurashtra Univ., Rajkot, India; H Rajagopal; Dept. of Phys., Saurashtra Univ., Rajkot, India; R G Kulkarni; Dept. of Phys., Saurashtra Univ., Rajkot, India
Журнал:
Superconductor Science and Technology
Дата:
1995-03-01
Аннотация:
We have investigated the influence of the incorporation of V ions with Cu ions on the structural features of the YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7- delta </sub> superconductor by Rietveld refinement of neutron diffraction patterns of two YBa<sub>2</sub>(Cu<sub>1-x</sub>V<sub>x</sub>)<sub>3</sub>O<sub>7- delta </sub> samples with (sample A) x=0.04 and (sample B) x=0.05. Neutron data confirm an orthorhombic structure with space group Pmmm for both samples, and the lattice parameters are in excellent agreement with those obtained from X-ray diffraction. The oxygen contents per formula unit of these samples are in good agreement with the iodometrically obtained values. V ions occupy Cu(1) and Cu(2) sites in equal proportions in the mixed valence state (4<sup>+</sup>, 5<sup>+</sup>) without affecting the orthorhombic structure and T<sub>c</sub> of the compound. A correlation exists between the Cu(1)-O(2) bond length and the measured T<sub>c</sub> values of both samples.
318.1Кб