Ordering principles and defect structure of {open_quotes}1201,{close_quotes} {open_quotes}1212,{close_quotes} and {open_quotes}1222{close_quotes} type (Hg, Pr)-Sr-(Sr,Ca,Pr)-Cu-O superconductors
- Universite de Caen (France)
- Univ. of Antwerp (Belgium)
The new families of superconducting compounds {open_quotes}1201{close_quotes} (Hg{sub 0.4}Pr{sub 0.6}Sr{sub 2}CuO{sub 4+{delta}}), {open_quotes}1212{close_quotes} (Hg{sub 0.4}Pr{sub 0.6}Sr{sub 2}(Ca{sub 1-x-y}Sr{sub x}Pr{sub y})Cu{sub 2}O{sub 6+{delta}}), and {open_quotes}1222{close_quotes} (Hg{sub 0.4}Pr{sub 0.6}Sr{sub 2}(Pr{sub 1.7}Sr{sub 0.3}){sub 2}Cu{sub 2}O{sub 8+{delta}}) all show ordering between praseodymium and mercury in the (Hg,Pr)O{sub {delta}} plane, reducing the symmetry from tetragonal to orthorhombic or even to monoclinic. In the 1201 compound the ordered superstructure can be described as O{sub 1} (a{sub 1} {approx} 2a{sub p}, b{sub 1} {approx} a{sub p}, c{sub 1} {approx} c{sub 1201}). In the 1212 compound two distinct superstructures are identified, O{sub 1} (a{sub 1} {approx} 2a{sub p}, b{sub II} {approx} a{sub p}, c{sub 1} {approx} c{sub 1212}) and O{sub II} (a{sub II} {approx} 2a{sub p}, b{sub II} {approx} a{sub p}, c{sub II} {approx} 2c{sub 1212}). In some compounds, such as Hg{sub 0.4}Pr{sub 0.6}Sr{sub 2}(Ca{sub 0.4}Sr{sub 0.4}Pr{sub 0.2}) Cu{sub 2}O{sub 6+{delta}}, the Hg-Pr ordering is only present in microdomains, but due to an ordering between Sr layers and Ca layers, the c-axis doubles and one obtains a tetragonal superstructure T{sub III} (a{sub III} {approx} a{sub p}, c{sub III} {approx} 2c{sub 1212}). In the 1222 compound, ordering in the (Pr,Hg)O{sub {delta}} plane is very defective; a large number of translation defects actually reduce the symmetry to triclinic.
- OSTI ID:
- 518219
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 114; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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