Title: Pd6CuB3 - a new structure type of borides. Th7Fe3-type derivative structures in Pd(Pt)-Cu-B systems
Language: English
Authors: Salamakha, Leonid
Sologub, Oksana 
Stöger, Berthold
Rogl, Peter 
Waas, Monika 
Michor, Herwig 
Bauer, Ernst 
Category: Original Research Article
Issue Date: 2017
Journal: Chemistry - A European Journal
ISSN: 1521-3765
Abstract: 
A missing member of the series of Th7Fe3-type derivative structures, h-(Pd0.864Cu0.136)7B3 (unique structure type Pd6CuB3, space group P63cm, a=12.9426(9) Å, c=4.8697(4) Å) was obtained from as cast alloys and alloys annealed at 600 °C - 650 °C. Further substitution of Cu by Pd led to formation of a Mn7C3-type structure, o-(Pd0.93Cu0.07)7B3 (space group Pnma, a=4.8971(2) Å, b=7.5353(3) Å, c=12.9743(6) Å). Isotypic h-(Pt0.70Cu0.30)7B3 was observed in the Pt-Cu-B system as a low temperature phase (T≤600 °C), whereas the B-filled Th7Fe3-type (HT h-(Pt0.717Cu0.283)7B3+x, space group P63mc, a=7.4424(12) Å, c=4.8549(8) Å) proved to be stable at high temperature. The three structures are built of columns of face connected metal octahedra and columns of metal tetrahedra alternatingly fused by common faces and vertices. Boron atoms are found in trigonal prisms formed by metal atoms; additionally octahedral boron coordination was encountered in HT h-(Pt0.717Cu0.283)7B3+x. A superconductivity was discovered for Pt4.9Cu2.1B3 (Pd6CuB3-type) and Pt5.04Cu1.96B3.3 (B-filled Th7Fe3-type) below 0.67 and 0.66 K, respectively. Despite the close value of the transition temperature the values of the upper critical field at 0 K differ as 0.37 T and 0.27 T for the two compounds.
DOI: 10.1002/chem.201602767
Library ID: AC11364805
URN: urn:nbn:at:at-ubtuw:3-3293
Organisation: E138 - Institut für Festkörperphysik 
Publication Type: Article
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