The crystal structures and superconductivity of a new series of superconducting phases

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Chinese Physics; (USA)

OSTI ID:6753832

Jingkui, Liang; Yuling, Zhang; Jiuqi, Huang; Sishen, Xie; Guanchan, Che; Xiangrong, Chen; Yongmin, Ni; Dongning, Zheng; Shunlian, Jia ^[1]

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1. Institute of Physics, Academia Sinica (CN)

We synthesized new superconducting phases in TlBa{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 2{ital n}+2.5} by solid state reaction. The crystal structures of TlBa{sub 2}CaCu{sub 2}O{sub 6.5} and TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 8.5} were determined by means of the x-ray powder diffraction method. The two compounds belong to a primary lattice with space group {ital D}{sup 1}{sub 4{ital h}}{minus}{ital P}4/{ital m}{ital m}{ital m}. The lattice constants of TlBa{sub 2}CaCu{sub 2}O{sub 6.5} are {ital a}=3.847 A, {ital c}=12.73 A. The lattice constants of TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 8.5} are {ital a}=3.847 A, {ital c}=15.89 A. Each cell contains one chemical formula unit. The cations are distributed alternately at positions of (0, 0, {ital z}) and (1/2, 1/2, {ital z}) along the {ital Z} axis. TlBa{sub 2}CaCu{sub 2}O{sub 6.5} shows zero resistance at 101.4 K. TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 8.5} shows zero resistance at 112 K. The oxygen-deficient pseudo-perovskite unit Ba{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 2{ital n}+1} is separated by a single Tl-O layer in the crystal structure of TlBa{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 2{ital n}+2.5}, while the oxygen deficient pseudo-perovskite unit Ba{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 2{ital n}} is separated by a bilayer of Tl-O in the crystal structure of Tl{sub 2}Ba{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 2{ital n}+2}. At the same {ital n} value, {ital T}{sub {ital c}} of Tl{sub 2}Ba{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 2{ital n}+4} is about 10 K higher than {ital T}{sub {ital c}} of TlBa{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 2{ital n}+2.5}.

• OSTI ID: 6753832
• Journal Information: Chinese Physics; (USA), Journal Name: Chinese Physics; (USA) Vol. 10:2; ISSN CHPHD; ISSN 0273-429X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
COHERENT SCATTERING
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
LATTICE PARAMETERS
LOW TEMPERATURE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SCATTERING
SUPERCONDUCTIVITY
THALLIUM COMPOUNDS
THALLIUM OXIDES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
X-RAY DIFFRACTION