Chemical modification of the superconducting oxides YBa[sub 2]Cu[sub 3]O[sub 7-x] and Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+x]

Thesis/Dissertation · Sat Jan 01 04:00:00 EST 1994

OSTI ID:6917137

Gloffke, W

A series of YBa[sub 2]Cu[sub 3[minus]x]W[sub x]O[sub y] compounds was synthesized. The results show a cubic system with a simple perovskite structure for x < 0.2 and a face-centered doubled perovskite cell for x > 0.2. There was no indication of the existence of the superconducting YBa[sub 2]Cu[sub 3]O[sub 7[minus]x] phase for x > 0.2. Solid solution of tungsten was exhibited over the composition region x > 0.2 as well as in the simple perovskite composition range. Rietveld analysis indicates that the composition can be more accurately described as a perovskite Ba[sub 2][(Cu,Y)W]O[sub 6] with a[sub 0] = 8.3430 [angstrom]. Analyses of samples of nominal composition YBa[sub 2]Cu[sub 2]WO[sub y] show it is non-superconducting. The iodine intercalate of Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+x] was synthesized and the kinetics of formation studied. Up to one iodine atom per Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+x] formula unit was incorporated into the structure; under the conditions of reaction, no staging was observed. The activation energy for the diffusion of iodine molecules into the interlayers of the structure was determined to be 45 kJ/mol. Modification of Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+x] by reaction with lithium was studied through solid state, chemical and electrochemical reactions. Lithium diffusion into the structure was found to saturate at about 0.3 Li per formula unit Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+x] when synthesized chemically. Solid state reaction products showed no evidence of lithium incorporation into the structure. Electrochemically up to 0.4 mol Li per formula unit Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+x] was intercalated; the lithium diffusion coefficient was found to be about 10[sup [minus]13] cm[sup 2]/s in that compound.

• Research Organization: State Univ. of New York, Binghamton, NY (United States)
• OSTI ID: 6917137
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
&amp; Refractories-- Structure &amp; Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical &amp; Physicochemical Properties
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
BARIUM COMPOUNDS
BARIUM OXIDES
BISMUTH COMPOUNDS
BISMUTH OXIDES
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
CHEMICAL PREPARATION
CLATHRATES
COPPER COMPOUNDS
CRYSTAL DOPING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
CUPRATES
HIGH-TC SUPERCONDUCTORS
INTERMETALLIC COMPOUNDS
IODINE ADDITIONS
LITHIUM ADDITIONS
LITHIUM ALLOYS
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
REFRACTORY METAL COMPOUNDS
SUPERCONDUCTORS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
TUNGSTEN OXIDES
YTTRIUM COMPOUNDS
YTTRIUM OXIDES