title: BaAl4 derivative phases in the sections {La,Ce}Ni2Si2-{La,Ce}Zn2Si2: phase relations, crystal structures and physical properties.
abstract: Phase relations and crystal structures have been evaluated within the sections LaNi2Si2-LaZn2Si2 and CeNi2Si2-CeZn2Si2 at 800 °C using electron microprobe analysis and X-ray powder and single crystal structure analyses. Although the systems La-Zn-Si and Ce-Zn-Si at 800 °C do not reveal compounds such as "LaZn2Si2" or "CeZn2Si2", solid solutions {La,Ce}(Ni1-xZnx)2Si2 exist with the Ni/Zn substitution starting from {La,Ce}Ni2Si2 (ThCr2Si2-type; I4/mmm) up to x = 0.18 for Ce(Ni1-xZnx)2Si2 and x = 0.125 for La(Ni1-xZnx)2Si2. For higher Zn-contents 0.25 ≤ x ≤ 0.55 the solutions adopt the CaBe2Ge2-type (P4/nmm). The investigations are backed by single crystal X-ray diffraction data for Ce(Ni0.61Zn0.39)2Si2 (P4/nmm; a = 0.41022(1) nm, c = 0.98146(4) nm; RF = 0.012) and by Rietveld refinement for La(Ni0.56Zn0.44)2Si2 (P4/nmm; a = 0.41680(6) nm, c = 0.99364(4) nm; RF = 0.043). Interestingly, the Ce-Zn-Si system contains a ternary phase CeZn2(Si1-xZnx)2 of the ThCr2Si2 structure type (0.25 ≤ x ≤ 0.30 at 600 °C), which forms peritectically at T = 695 °C but does not include the composition "CeZn2Si2". The primitive high temperature tetragonal phase with the CaBe2Ge2-type has also been observed for the first time in the Ce-Ni-Si system at CeNi2+xSi2-x, x = 0.33 (single crystal data, P4/nmm; a = 0.40150(2) nm, c = 0.95210(2) nm; RF = 0.0163). Physical properties (from 400 mK to 300 K) including specific heat, electrical resistivity and magnetic susceptibility have been elucidated for Ce(Ni0.61Zn0.39)2Si2 and La(Ni0.56Zn0.44)2Si2. Ce(Ni0.61Zn0.39)2Si2 exhibits a Kondo-type ground state. Low temperature specific heat data of La(Ni0.56Zn0.44)2Si2 suggest a spin fluctuation scenario with an enhanced value of the Sommerfeld constant.
authors.affiliation: Institute of Materials Chemistry and Research, University of Vienna, Währingerstraße 42, A-1090 Vienna, Austria. fai.failamani@gmail.com zahida.malik@sns.nust.edu.pk andriy.grytsiv@univie.ac.at peter.franz.rogl@univie.ac.at.
authors.forename: Fainan
authors.initials: F
authors.lastname: Failamani
authors.affiliation: Institute of Materials Chemistry and Research, University of Vienna, Währingerstraße 42, A-1090 Vienna, Austria. fai.failamani@gmail.com zahida.malik@sns.nust.edu.pk andriy.grytsiv@univie.ac.at peter.franz.rogl@univie.ac.at.
authors.forename: Zahida
authors.initials: Z
authors.lastname: Malik
authors.affiliation: Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria. salamakhaleonid@rambler.ru kneidinger@ifp.tuwien.ac.at michor@ifp.tuwien.ac.at bauer@ifp.tuwien.ac.at.
authors.forename: Leonid
authors.initials: L
authors.lastname: Salamakha
authors.affiliation: Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria. salamakhaleonid@rambler.ru kneidinger@ifp.tuwien.ac.at michor@ifp.tuwien.ac.at bauer@ifp.tuwien.ac.at.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Kneidinger
authors.affiliation: Institute of Materials Chemistry and Research, University of Vienna, Währingerstraße 42, A-1090 Vienna, Austria. fai.failamani@gmail.com zahida.malik@sns.nust.edu.pk andriy.grytsiv@univie.ac.at peter.franz.rogl@univie.ac.at and Christian Doppler Laboratory for Thermoelectricity, Vienna, Austria.
authors.forename: Andriy
authors.initials: A
authors.lastname: Grytsiv
authors.affiliation: Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria. salamakhaleonid@rambler.ru kneidinger@ifp.tuwien.ac.at michor@ifp.tuwien.ac.at bauer@ifp.tuwien.ac.at.
authors.forename: Herwig
authors.initials: H
authors.lastname: Michor
authors.affiliation: Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10, A-1040 Vienna, Austria. salamakhaleonid@rambler.ru kneidinger@ifp.tuwien.ac.at michor@ifp.tuwien.ac.at bauer@ifp.tuwien.ac.at and Christian Doppler Laboratory for Thermoelectricity, Vienna, Austria.
authors.forename: Ernst
authors.initials: E
authors.lastname: Bauer
authors.affiliation: Institute of Mineralogy and Crystallography, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria. gerald.giester@univie.ac.at.
authors.forename: Gerald
authors.initials: G
authors.lastname: Giester
authors.affiliation: Institute of Materials Chemistry and Research, University of Vienna, Währingerstraße 42, A-1090 Vienna, Austria. fai.failamani@gmail.com zahida.malik@sns.nust.edu.pk andriy.grytsiv@univie.ac.at peter.franz.rogl@univie.ac.at and Christian Doppler Laboratory for Thermoelectricity, Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Rogl