Cage-Forming Compounds in the Ba-Rh-Ge System: From Thermoelectrics to Superconductivity

Autor(en)

Matthias Falmbigl, F. Kneidinger, Mingxing Chen, Andrij Grytsiv, Herwig Michor, Esmaeil Royanian, Ernst Bauer, Herta Silvia Effenberger, Raimund Podloucky, Peter Franz Rogl

Abstrakt

Phase relations and solidification behavior in the Ge-rich part of the phase diagram have been detd. in two isothermal sections at 700 and 750 °C and in a liquidus projection. A reaction scheme has been derived in the form of a Schulz-Scheil diagram. Phase equil. are characterized by three ternary compds.: t1-BaRhGe3 (BaNiSn3-type) and two novel phases, t2-Ba3Rh4Ge16 and t3-Ba5Rh15Ge36-x, both forming in peritectic reactions. The crystal structures of t2 and t3 have been elucidated from single-crystal X-ray intensity data and were found to crystallize in unique structure types: Ba3Rh4Ge16 is tetragonal (I4/mmm, a = 0.65643(2) nm, c = 2.20367(8) nm, and RF = 0.0273), whereas atoms in Ba5Rh15Ge36-x (x = 0.25) arrange in a large orthorhombic unit cell (Fddd, a = 0.84570(2) nm, b = 1.4725(2) nm, c = 6.644(3) nm, and RF = 0.034). The body-centered-cubic superstructure of binary Ba8Ge43[]3 was obsd. to extend at 800 °C to Ba8Rh0.6Ge43[]2.4, while the clathrate type I phase, ?I-Ba8RhxGe46-x-y[]y, reveals a max. soly. of x = 1.2 Rh atoms in the structure at a vacancy level of y = 2.0. The cubic lattice parameter increases with increasing Rh content. Clathrate I decomps. eutectoidally at 740 °C: ?I

Organisation(en)

Institut für Physikalische Chemie, Institut für Theoretische Chemie, Institut für Mineralogie und Kristallographie

Externe Organisation(en)

Technische Universität Wien

Journal

Inorganic Chemistry

Band

52

Seiten

931-943

Anzahl der Seiten

13

ISSN

0020-1669

DOI

https://doi.org/10.1021/ic302139r

Publikationsdatum

2013

Peer-reviewed

Ja

ÖFOS 2012

104017 Physikalische Chemie, 105113 Kristallographie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/d49119b2-0da5-407e-b660-432cf6d1c38c