Introduction of lanthanide on the mercury site of the HgBa{sub 2}CuO{sub 4} superconductor

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Materials Research Bulletin

DOI:https://doi.org/10.1016/0025-5408(96)00049-9· OSTI ID:271756

Letouze, F; Huve, M; Martin, C; Maignan, A; Michel, C; Hervieu, M; Raveau, B ^[1]

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1. Univ. de Caen (France)

This investigation of the substitution of lanthanides for mercury in the HgBa{sub 2}CuO{sub 4+{delta}} structure has shown that 1201 cuprates Hg{sub 1{minus}x}Ln{sub x}Ba{sub 2}CuO{sub 4+{delta}} can be synthesized for Ln = Ce, Pr, Nd with x {approx} 0.15; whereas for Ln = Sm, Eu, Gd, lanthanide does not enter into the matrix. The XRD and HREM studies confirm the 1201-type structure and show the statistical distribution of mercury and lanthanides within the mixed [Hg{sub 1{minus}x}Ln{sub x}O{sub {delta}}]{sub {infinity}} layer. In contrast to the homologous strontium phases Hg{sub 1{minus}x}Ln{sub x}Sr{sub 2}CuO{sub 4+{delta}}, these barium cuprates exhibit superconducting properties, with {Tc} ranging from 55 K to 83 K when as-synthesized. Annealing in a reducing atmosphere increases T{sub c} significantly, showing that the as-synthesized samples are all overdoped. The most important feature deals with the fact that the critical temperature and the narrow character of the transition for the annealed samples are improved as the size of the lanthanide cation increases, the best characteristics being obtained for the cerium phase that exhibits a {Tc} of 90 K.

• OSTI ID: 271756
• Journal Information: Materials Research Bulletin, Journal Name: Materials Research Bulletin Journal Issue: 6 Vol. 31; ISSN MRBUAC; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
CERIUM OXIDES
CHEMICAL COMPOSITION
COPPER OXIDES
CRYSTAL STRUCTURE
ELECTRON DIFFRACTION
HIGH-TC SUPERCONDUCTORS
MERCURY OXIDES
NEODYMIUM OXIDES
PRASEODYMIUM OXIDES
SOLID SOLUTIONS
SUPERCONDUCTIVITY
SYNTHESIS
TETRAGONAL LATTICES
TRANSITION TEMPERATURE
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY