Th7Fe3-Type Related Structures in Pd(Pt)-Cu-B Systems: Pd(6)CuB(3)A New Structure Type for Borides

Leonid P. Salamakha, Oksana Sologub (Korresp. Autor*in), Berthold Stoeger, Peter F. Rogl, Monika Waas, Herwig Michor, Ernst Bauer

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed


A new member of the series of Th 7Fe 3-type derivative structures, h-(Pd 0.86Cu 0.14) 7B 3 (≡Pd 6.02Cu 0.98B 3, unique structure type Pd 6CuB 3, space group P6 3cm, a=12.9426(9) Å, c=4.8697(4) Å, single-crystal X-ray diffraction (XRD) data) was obtained from as cast alloys and alloys annealed at 600–650 °C. Further substitution of Cu by Pd led to formation of a Mn 7C 3-type structure, o-(Pd 0.93Cu 0.07) 7B 3 (≡Pd 6.51Cu 0.49B 3, space group Pnma, a=4.8971(2) Å, b=7.5353(3) Å, c=12.9743(6) Å, single-crystal XRD). Isotypic LT h-(Pt 0.70Cu 0.30) 7B 3 (≡Pt 4.90Cu 2.10B 3) was observed in the Pt-Cu-B system as a low-temperature (LT) phase (T≤600 °C) (powder XRD), whereas the Th 7Fe 3-type (high-temperature (HT) h-(Pt 0.73Cu 0.27) 7B 3≡Pt 5.11Cu 1.89B 3, space group P6 3mc, a=7.4671(1) Å, c=4.9039(1) Å, powder XRD) 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. The volumes of the three new Th 7Fe 3-type derivative borides relate as 1:2:3. Superconductivity was discovered for Pt 4.9Cu 2.1B 3 (Pd 6CuB 3-type) and Pt 5.1Cu 1.9B 3 (Th 7Fe 3-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.

Seiten (von - bis)4810-4817
FachzeitschriftChemistry: A European Journal
PublikationsstatusVeröffentlicht - 6 Apr. 2017

ÖFOS 2012

  • 104017 Physikalische Chemie
  • 104011 Materialchemie