Structural studies of the BaPb/sub 1-x/Bi/sub x/O/sub 3/ system

Conference · Thu Jan 01 04:00:00 EST 1976

OSTI ID:7259662

Cox, D E; Sleight, A W

Superconductivity has recently been observed in the BaPb/sub 1-x/Bi/sub x/O/sub 3/ system for x between 0.05 and 0.3, the highest transition temperature being around 13/sup 0/K. Structural studies have been carried out at 25/sup 0/C by means of x-ray Guinier techniques and profile refinement of neutron powder data. BaPbO/sub 3/ is orthorhombic, space group Ibmm, and has a distorted perovskite-type structure in which the Pb atoms occupy one set of equivalent positions with the surrounding oxygen octahedra tilted roughly 8/sup 0/ about a pseudo-cubic (110) axis. BaBiO/sub 3/ has a basically similar structure, but in this case the Bi atoms are situated on two sets of octahedral sites, and there is an additional shift in the position of the oxygen atoms of about 0.1A from one set of sites towards the other, consistent with ordering of Bi/sup 3 +/ and Bi/sup 5 +/. The resulting symmetry is monoclinic, space group I2/m. The superconducting region is characterized by a tetragonal structure at 25/sup 0/C, space group I4/mcm, similar to that of the low temperature form of SrTiO/sub 3/. In BaPb/sub 0/./sub 7/Bi/sub 0/./sub 3/O/sub 3/, the oxygen octahedra are tilted roughly 8/sup 0/ about the (001) axis. For x between 0.4 and 0.75, orthorhombic symmetry is once again observed.

• Research Organization: Brookhaven National Lab., Upton, N.Y. (USA)
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• DOE Contract Number: E(30-1)-16
• OSTI ID: 7259662
• Report Number(s): BNL-21484; CONF-760601-3
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656000 -- Condensed Matter Physics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BISMUTH COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
LEAD COMPOUNDS
MOLECULAR STRUCTURE
NEUTRON DIFFRACTION
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SCATTERING
SUPERCONDUCTIVITY