Phase equilibria, superconductivity, and flux creep in Nd sub 1+x Ba sub 2-x Cu sub 3 O sub 7+. delta. superconductors
NdBa{sub 2}CU{sub 3}O{sub 7} (Ndl23) is one of REBa{sub 2}CU{sub 3}O{sub 7} (RE123) superconductors (RE = Y and rare earths), having {Tc} of about 90 K. The phase diagram in the Nd-Ba-Cu-O system, superconductivity in Ndl23ss, and the role of Nd substitution for Ba sites as the magnetic flux pinning sites were investigated. The discrepancies in published phase diagrams were clarified. Significant results contain the solubility limits of 0.04{le} {times} {le} 0.6 in Ndl23ss, the existence of Nd{sub 2}BaCuO{sub 10} having a solid solution, and a discovery of a new phase NdBa{sub 6}CU{sub 3}O{sub y}. Superconductivity in Nd{sub l+x}Ba{sub 2-x}CU{sub 3}O{sub 7+{delta}} was studied for well- characterized samples with sharp transitions. With the substitution of Nd{sup +3} for Ba{sup +2}, there is an increase in the O(5) sites surrounding this substitution. While for x > O.l there is a significant depression of{Tc}, for x < O.l there is no substantial decrease in {Tc} within experimental error. {Tc} vs x is characterized by two plateaus analogous to {Tc} vs d in YBa{sub 2}CU{sub 3}O{sub 7-d}. Analysis of O content of Ndl23ss suggests the analogy with Y123 is valid. Transition width and Meissner fraction for all Ndl23ss samples are strongly dependent on the sintering temperature. Hysteresis show good intragranular critical currents (J{sub c}) at high fields but still low intergranular. Since the magnetic fields penetrate a Type II superconductor at high field, flux lines must be pinned to increase the J{sub c}. While {Tc} is not affected over the range 0 < {times} < 0. 1, the oxygens surrounding the substituted Ba sites are expected to locally suppress the superconducting order parameter. Such a local suppression of the order parameter may act as a flux pinning site. Hysteresis exhibits a small increase in the magnetic J{sub c}, but flux creep measurements show no apparent effects of this substitution on flux pinning energy.
- Research Organization:
- Ames Lab., IA (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 7229029
- Report Number(s):
- IS-T-1613; ON: DE93001223
- Country of Publication:
- United States
- Language:
- English
Similar Records
Superconductivity and flux pinning in Nd[sub 1+x]Ba[sub 2-x]Cu[sub 3]O[sub 7+[delta]]
Superconductivity and flux pinning in Nd{sub 1+x}Ba{sub 2-x}Cu{sub 3}O{sub 7+{delta}}
Related Subjects
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360207 -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HIGH-TC SUPERCONDUCTORS
HYSTERESIS
MAGNETIC FLUX
NEODYMIUM COMPOUNDS
NEODYMIUM OXIDES
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SUPERCONDUCTIVITY
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE