11 research outputs found
Studies on La2-xPrxCayBa2Cu4+yOz (0.1 < x < 0.5) type mixed oxide superconductors
The La2-xPrxCayBa2Cu4+yOz (LaPrCaBCO) mixed oxides have been studied for
their structural and superconducting properties using X-ray diffraction (XRD),
d. c. resistivity, d. c. susceptibility and iodometric double titration. All
the LaPrCaBCO samples for x = 0.1 - 0.5, exhibit tetragonal crystalline
structure with P 4/mmm space group as determined by Rietveld analysis of the
X-ray diffraction data. With increasing x, enhancement in Tc is observed, which
is quite interesting for Pr substituted high Tc oxides. Maximum Tc ~ 58 K has
been observed for x = 0.5(La-2125 stoichiometry). The results of structural
studies and superconducting property measurements are presented in light of
increase in Tc in LaPrCaBCO system with increasing Pr concentration.Comment: 6 pages including 5 figures and 1 tabl
Critical current density and flux pinning in La2-xPrxCa2xBa2Cu4+2xOz (x = 0.1 - 0.5) superconductors
Polycrystalline La2-xPrxCa2xBa2Cu4+2xOz (LPCaBCO) compounds with x = 0.1 -
0.5 were synthesized by solid-state reaction method and studied by room
temperature X-ray diffraction, dc resistivity, dc magnetization and iodometry.
The superconducting transition temperatures in these tetragonal triple
perovskite compounds increases from 32 to 62 K (Tconset values) with increasing
dopant concentration. The mixing of rare earth La3+ and Pr3+/4+ ions at rare
earth site (La3+) along with substitution of divalent Ca2+ results in the
shrinkage of unit cell volume. The contraction of unit cell volume due to
larger ion being substituted by smaller ions, gives rise to creation of pinning
centers in the unit cell leading to increase in critical current density and
flux pinningComment: To be published in Solid State Communications (2004