Effects of getter annealing and codoping of iron and zinc in yttrium-barium cuprates

Journal Article · Thu Sep 01 00:00:00 EDT 1994 · Materials Research Bulletin; (United States)

DOI:https://doi.org/10.1016/0025-5408(94)90059-0· OSTI ID:6917480

O'Brien, J R; Oesterreicher, H ^[1]; Taylor, R D ^[2]

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1. Univ. of California, San Diego, La Jolla, CA (United States)
2. Los Alamos National Lab., NM (United States). Physics Division

This study explores issues connected with the complex structural and electronic behavior of partly substituted YBa[sub 2](Cu[sup 1[minus]x[minus]z]Fe[sub x]Zn[sub z])[sub 3]O[sub y] when given special redox sequencing over varying times. For z = 0 and x = 0.03 conventional oxygenated slow cooling preparations (OP) yield tetragonal materials with [Tc][sub mid] = 59K. Getter annealing procedures using Gd to control the extent of reduction to y = 6.1 at 1000K for 4 days followed by reoxidation at 700K for 1 hour yield orthorhombic materials with [Tc][sub mid] = 68K and improved superconducting volume fractions. The results are in line with expectations for the presence of ordered atomic size Fe clusters with these reducing preparations (RP). This redox sequence also reduces the paramagnetic Curie temperature from [Theta][sub P] = [minus]35K to [Theta][sub P] = [minus]51K for z = 0, hinting at higher cluster Neel temperatures. When the getter annealed specimen is air annealed for prolonged times (50h) at 673K, a broader [Tc] transition develops and a slight decrease in the orthorhombic splitting is observed. This demonstrates that small rearrangements from properties of RP to OP are possible even at these low temperatures. Codoping to x = 0.03, z = 0.01 results in drastic reductions to [Tc][sub mid] = 31K for OP, beyond the one expected from individual contributions, while structural parameters do not change noticeably. This synergistic effects is also reflected in [Theta][sub P] and may have to do with a large proportion of Fe occupying the Cu(2) site. Results are discussed within models of inhomogeneous M distributions and oxygen chain order.

• OSTI ID: 6917480
• Journal Information: Materials Research Bulletin; (United States), Vol. 29:9; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
ANNEALING
MICROSTRUCTURE
COPPER OXIDES
IRON OXIDES
YTTRIUM OXIDES
ZINC OXIDES
REDOX POTENTIAL
TRANSITION TEMPERATURE
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
HEAT TREATMENTS
IRON COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
ZINC COMPOUNDS
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication
360202 - Ceramics
Cermets
& Refractories- Structure & Phase Studies