The system Ce-Zn-Si for <33.3% at. Ce

Autor(en)

Fainan Failamani, Andrij Grytsiv, Raimund Podloucky, Herwig Michor, Ernst Bauer, Pavel Broz, Gerald Giester, Peter Franz Rogl

Abstrakt

Phase equil. of the system Ce-Zn-Si have been detd. for the isothermal section at 600°C for <33.3 at.% Ce by XRPD and EPMA. The section is characterized by the formation of seven ternary compds. with homogeneity regions at const. Ce-content and partial substitution of Zn/Si: t1-Ce7Zn21(Zn1-xSix)2 (unique type; 0.45=x=0.99), t2-Ce(Si1-xZnx)2 (AlB2-type; 0.36=x=0.73), t5-CeZn(Zn1-xSix)2 (CeNiSi2-type; 0.68=x=0.76), t6-CeZn2(Si1-xZnx)2 (ThCr2Si2-type; 0.25=x=0.30) and t7-Ce37Zn48Si15 (structure unknown). Whereas t1, t2 and t5 are stable at 600 and 800 °C, the phases t6, t7 are unstable at 800°C. The small amts. of the stabilizing tetrel element in {La,Ce}7Zn21[Zn1-xSi(Ge)x]2 suggest a hypothetical binary phase "{La,Ce}7Zn23". Atom site distribution in the crystal structures of t5, t6 and the {La,Ce}7Zn21(Zn1-xGex)2 have been elucidated from X-ray intensity refinements on single crystals. The stabilizing effect of Ge in Ce7Zn23-xGex has been elucidated from d. functional theory (DFT) calcns. discussing the electronic structure in terms of the d. of states (DOS) and defining enthalpies of formation for Ce7Zn23-xGex (x=0, 0.5, 2) as well as for several neighboring binary Ce-Zn phases. A Schultz-Scheil diagram for the solidification behavior in the (Zn,Si)-rich part of the diagram was constructed from DTA measurements in closed silica crucibles along with partial isothermal sections detd. in the temp. range from 400 to 900°C. The phases t5 and t6 both form in degenerate ternary peritectic reactions: L + (CeSi2,ß-Ce2Zn17) = t5 at 865±5°C and L + (t5,CeZn11) = t6 at 695±5°C, resp. Magnetic susceptibility, sp. heat and resistivity measurements of t5-CeZn(Si1-xZnx)2 revealed Kondo lattice behavior with ferromagnetic ordering below TC=4.4 K, whereas susceptibility and sp. heat studies of t6-CeZn2(Zn0.28Si0.72)2 revealed Curie-Weiss paramagnetic behavior down to 3 K. The effective paramagnetic moments of Ce obtained from Curie-Weiss fits of t5 (2.48 µB) and t6 (2.34 µB) reveal a ground state close to trivalent Ce.

Organisation(en)

Institut für Physikalische Chemie, Institut für Mineralogie und Kristallographie

Externe Organisation(en)

Technische Universität Wien, Masaryk University

Journal

RSC Advances

Band

5

Seiten

36480-36497

Anzahl der Seiten

18

ISSN

2046-2069

DOI

https://doi.org/10.1039/c5ra02789f

Publikationsdatum

03-2015

Peer-reviewed

Ja

ÖFOS 2012

104017 Physikalische Chemie, 104011 Materialchemie, 105113 Kristallographie

Schlagwörter

ASJC Scopus Sachgebiete

Chemical Engineering(all), Chemistry(all)

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/the-system-ceznsi-for-333-at-ce(9c43ad5c-7318-4bba-b56e-542a8add20fe).html