Pt-B system revisited: Pt2B, a new structure type of binary borides. Ternary WAl12-type derivative borides
- Autor(en)
- Oksana Sologub, Leonid P. Salamakha, Peter Franz Rogl, Berthold Stöger, Ernst Bauer, Johannes Bernardi, Gerald Giester, Monika Waas, Robert Svagera
- Abstrakt
On the basis of a detailed study applying X-ray single-crystal and powder diffraction, differential scanning calorimetry, and scanning electron microscopy analysis, it was possible to resolve existing uncertainties in the Pt-rich section (=65 atom % Pt) of the binary Pt-B phase diagram above 600 °C. The formation of a unique structure has been observed for Pt2B [X-ray single-crystal data: space group C2/m, a = 1.62717(11) nm, b = 0.32788(2) nm, c = 0.44200(3) nm, ß = 104.401(4)°, RF2 = 0.030]. Within the homogeneity range of "Pt3B", X-ray powder diffraction phase analysis prompted two structural modifications as a function of temperature. The crystal structure of "hT-Pt3B" complies with the hitherto reported structure of anti-MoS2 [space group P63/mmc, a = 0.279377(2) nm, c = 1.04895(1) nm, RF = 0.075, RI = 0.090]. The structure of the new "T-Pt3B" is still unknown. The formation of previously reported Pt~4B has not been confirmed from binary samples. Exploration of the Pt-rich section of the Pt-Cu-B system at 600 °C revealed a new ternary compound, Pt12CuB6-y [X-ray single-crystal data: space group Im3¯, a = 0.75790(2) nm, y = 3, RF2 = 0.0129], which exhibits the filled WAl12-type structure accommodating boron in the interstitial trigonal-prismatic site 12e. The isotypic platinum-aluminum-boride was synthesized and studied. The solubility of copper in binary platinum borides has been found to attain ~7 atom % Cu for Pt2B but to be insignificant for "T-Pt3B". The architecture of the new Pt2B structure combines puckered layers of boron-filled and empty [Pt6] octahedra (anti-CaCl2-type fragment) alternating along the x axis with a double layer of boron-semifilled [Pt6] trigonal prisms interbedded with a layer of empty tetrahedra and tetragonal pyramids (B-deficient a-TI fragment). Assuming boron vacancies ordering (space group R3), the Pt12CuB6-y structure exhibits serpentine-like columns of edge-connected boron-filled [Pt6] trigonal prisms running infinitely along the z axis and embedding the icosahedrally coordinated Cu atom. Pt2B, (Pt1-yCuy)2B (y = 0.045), and Pt12CuB6-y (y = 3) behave metallically, as revealed by temperature-dependent electrical resistivity measurements.
- Organisation(en)
- Institut für Materialchemie, Institut für Mineralogie und Kristallographie
- Externe Organisation(en)
- Technische Universität Wien
- Journal
- Inorganic Chemistry
- Band
- 54
- Seiten
- 10958-10965
- Anzahl der Seiten
- 8
- ISSN
- 0020-1669
- DOI
- https://doi.org/10.1021/acs.inorgchem.5b01998
- Publikationsdatum
- 11-2015
- Peer-reviewed
- Ja
- ÖFOS 2012
- 104017 Physikalische Chemie, 104011 Materialchemie, 105113 Kristallographie, 104024 Röntgenstrukturanalyse
- Schlagwörter
- ASJC Scopus Sachgebiete
- Inorganic Chemistry, Physical and Theoretical Chemistry
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/ptb-system-revisited-pt2b-a-new-structure-type-of-binary-borides-ternary-wal12type-derivative-borides(f71d783b-45d0-4b9d-ac41-cab42fef9fa0).html