Synthesis, characterization, and thermoelectric power study of thallium-based high Tc superconductors

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5427975

Xin, Ying

New Tl-based 1,212 type superconductors, 100K (Tl{sub 0.8}Pb{sub 0.2})-Sr{sub 2}(R,Sr) Cu{sub 2}O{sub 7{minus}{delta}} and 110K TlSr{sub 2}(Ca, Cr)Cu{sub 2}O{sub 7{minus}{delta}} have been synthesized and studied on superconductivity and crystal structure. Systematically study on the thallium-based nominal MTlBaCuO{sub x} (M = Zn, Cd, and Hg), TlSr{sub 2} (R,Sr)Cu{sub 2}O{sub x} (R = rare earths), and Tl{sub 2}M{sub 0.2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (M = Na, K, Rb, Cr, Re, Zn, Cd, Hg, Se, and Te) samples have been conducted. The investigations were performed by resistance and ac susceptibility measurements, and powder x-ray diffraction. The addition of Zn, Cd, or H g into Tl-Ba-Cu-O has some remarkable influences on superconductivity and mechanical properties as well as the required preparation condition. For the Tl(Tl,Pb)-Sr-R-Cu-O 1,212 type system the optimum composition and the elemental effect of different rare earths are discussed and concluded in terms of the average Cu valence in the CuO{sub 2} plane and the ionic radii of the rare earths. The partial substitution of Pb for Tl raises the {Tc} in TlS{sub 2}(R,Sr)Cu{sub 2}O{sub x} by about 10 degrees. High quality Tl-(M)-Ba-Ca-Cu-O 2,223 superconductors were synthesized by a novel preparation procedure. The 2,223 material with {Tc} of about 120 K and phase purity greater than 95% exhibits much improved mechanical properties. A convenient and reliable thermoelectric power measurement apparatus has been established. Measurements on the 1,212 phase TlSr{sub 2} (Er{sub 1{minus}y}Sr{sub y})Cu{sub 2}O{sub 7{minus}{delta}} and 2,223 phase Tl{sub 2}M{sub 0.2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10{minus}{delta}} were carried out.

• Research Organization: Arkansas Univ., Fayetteville, AR (United States)
• OSTI ID: 5427975
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
360207 -- Ceramics
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& Refractories-- Superconducting Properties-- (1992-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
CHEMICAL PREPARATION
COHERENT SCATTERING
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HIGH-TC SUPERCONDUCTORS
LEAD COMPOUNDS
LEAD OXIDES
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SCATTERING
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTIVITY
SUPERCONDUCTORS
SYNTHESIS
THALLIUM COMPOUNDS
THALLIUM OXIDES
THERMODYNAMIC PROPERTIES
THERMOELECTRIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
X-RAY DIFFRACTION