Bismuth cuprate high-T/sub c/ superconductors using cationic substitution
The Bi/sub 4/Sr/sub 4/Ca/sub 2-//sub x/R/sub x/Cu/sub 4/BO/sub y/ materials (R is a rare-earth element) were studied to determine their structural and physical properties. For most of the rare-earth elements, a complete solid solution exists up to x = 2. Below x = 0.5,T/sub c/ is not affected and for each added rare-earth element we find that about 0.5 oxygen atom is added to the structure. However, the structural modulation observed along the b axis for the undoped material persists and remains of the same amplitude for the rare-earth-doped samples. When more than one R(xgreater than or equal to1) is substituted, T/sub c/ is depressed and the compound becomes semiconducting beyond x = 1.5. The depression in the T/sub c/ from 85 K (x = 0) to less than 4.2 K (x = 1.5) correlates to a decrease in the formal valence of copper and is independent whether the rare-earth element is magnetic or nonmagnetic. No evidence for magnetic ordering over the range of temperature 1.7--400 K has been observed in all the substituted compounds. The substitution for Cu by 3d metals or for Sr by rare-earth elements fails for the 85-K Bi phase but succeeds for the 10-K Bi phase. Consequently, the following series Bi/sub 2/Sr/sub 2/Cu/sub 1-//sub x/M/sub x/O/sub y/ (M = Fe, Co) and Bi/sub 2/RCaCuO/sub y/ (R = La, Pr, Nd, Sm) were made for study. These substitutions result in an uptake of oxygen (0.5 for each substituted element). But the materials become semiconducting even though the formal valence of Cu remains greater than 2. An antiferromagnetic transition at 140 K has been found for the Co sample for which Co is found to be in the +3 state.
- Research Organization:
- Bellcore, Red Bank, New Jersey 07701
- OSTI ID:
- 6359732
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Vol. 39:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BISMUTH OXIDES
SUPERCONDUCTIVITY
CALCIUM OXIDES
COPPER OXIDES
RARE EARTH COMPOUNDS
STRONTIUM OXIDES
DOPED MATERIALS
SUBSTOICHIOMETRY
TRANSITION TEMPERATURE
VALENCE
ALKALINE EARTH METAL COMPOUNDS
BISMUTH COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
MATERIALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
STRONTIUM COMPOUNDS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties
656100 - Condensed Matter Physics- Superconductivity