Cationic substitution and role of oxygen in the n -type superconducting T prime system Nd sub 2 minus y Ce sub y CuO sub z

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.6582· OSTI ID:7122561

Wang, E; Tarascon, J; Greene, L H; Hull, G W ^[1]; McKinnon, W R ^[2]

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1. Bellcore, 331 Newman Springs Road, Red Bank, New Jersey 07701 (USA)
2. National Research Council of Canada, Ottawa, Canada K1A0R9 (CA)

The effect of oxygen content and cationic substitution on the structural and superconducting properties of the {ital T}{prime} phase were studied by investigating the Nd{sub 2{minus}{ital y}}Ce{sub {ital y}}CuO{sub {ital z}} and {ital R}{sub 1.85{minus}{ital x}{ital R}}{sup {prime}}{sub {ital x}}{ital M}{sub 0.15}CuO{sub {ital z}} ({ital R}=Nd,Eu; {ital R}{prime}=La,Y; {ital M}=Ce,Th; {ital z}{approx equal}4) series. We find that solid solutions of the {ital T}{prime} phases can be prepared, and the solubility range of La and Y depends on the sizes of the host versus the dopant ions. The transition from tetragonal {ital T}{prime} phase to the orthorhombic {ital T} phase is quite abrupt, without evidence for the {ital T}{sup *} phase. In this system, as for the La-Sr-Cu-O system, we find that superconductivity seems to correlate with the in-plane Cu-Cu distance, and there is a critical distance (3.95 A) for which {ital T}{sub {ital c}} is maximum. The as-prepared Ce- or Th-doped materials have an oxygen content per unit formula greater than four, and when heated under nitrogen they lose oxygen in two steps at temperatures of 400 and 800 {degree}C, with the amount of oxygen lost through each step being strongly dependent on sample processing. The total amount of mobile oxygen lost decreases with increasing Ce or Th content. From thermogravimetric-analysis measurements we show the crucial importance of the reducing step at temperatures greater than 850 {degree}C for inducing superconductivity as well as the importance of the cooling rate on the superconducting properties of the {ital T}{prime} phases. The importance of oxygen disorder to the normal-state properties is demonstrated.

• OSTI ID: 7122561
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 41:10; ISSN 0163-1829; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
CERIUM COMPOUNDS
CERIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRONIC STRUCTURE
ELEMENTS
MATERIALS
N-TYPE CONDUCTORS
NEODYMIUM COMPOUNDS
NEODYMIUM OXIDES
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SEMICONDUCTOR MATERIALS
STOICHIOMETRY
SUPERCONDUCTIVITY
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE