BaAl4 derivative phases in the sections {La, Ce}Ni2Si2–{La, Ce}Zn2Si2: phase relations, crystal structures and physical properties12. Issue 12 (19th February 2016)

• Record Type: Journal Article
• Authors: Failamani, Fainan; Malik, Zahida; Salamakha, Leonid; Kneidinger, Friedrich; Grytsiv, Andriy; Michor, Herwig; Bauer, Ernst; Giester, Gerald; Rogl, Peter
• Is Part Of: Dalton transactions. Volume 45:Issue 12(2016)
• Page Start: 5262
• Page End: 5273
• Publication Date: 2016-02-19
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c5dt04705f
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Phase relations, crystal structures and physical properties of the BaAl4 derivative phases within the sections LaNi2 Si2 –LaZn2 Si2 and CeNi2 Si2 –CeZn2 Si2 at 800 °C have been evaluated. Abstract : Phase relations and crystal structures have been evaluated within the sections LaNi2 Si2 –LaZn2 Si2 and CeNi2 Si2 –CeZn2 Si2 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 "LaZn2 Si2 " or "CeZn2 Si2 ", solid solutions {La, Ce}(Ni1− x Zn x )2 Si2 exist with the Ni/Zn substitution starting from {La, Ce}Ni2 Si2 (ThCr2 Si2 -type; I 4/ mmm ) up to x = 0.18 for Ce(Ni1− x Zn x )2 Si2 and x = 0.125 for La(Ni1− x Zn x )2 Si2 . For higher Zn-contents 0.25 ≤ x ≤ 0.55 the solutions adopt the CaBe2 Ge2 -type ( P 4/ nmm ). The investigations are backed by single crystal X-ray diffraction data for Ce(Ni0.61 Zn0.39 )2 Si2 ( P 4/ nmm ; a = 0.41022(1) nm, c = 0.98146(4) nm; R F = 0.012) and by Rietveld refinement for La(Ni0.56 Zn0.44 )2 Si2 ( P 4/ nmm ; a = 0.41680(6) nm, c = 0.99364(4) nm; R F = 0.043). Interestingly, the Ce–Zn–Si system contains a ternary phase CeZn2 (Si1− x Zn x )2 of the ThCr2 Si2 structure type (0.25 ≤ x ≤ 0.30 at 600 °C), which forms peritectically at T = 695 °C but does not include the composition "CeZn2 Si2 ". The primitive high temperature tetragonal phase with the CaBe2 Ge2 -type has also been observed for the first time in the Ce–Ni–Si system at CeNi2+ x Si2− x, x = 0.33 (single crystal data, P 4/ nmm ; a = 0.40150(2) nm, c = 0.95210(2) nm; R F = 0.0163). Physical properties (from 400 mK to 300 K) including specific heat, electrical resistivity and magnetic susceptibility have been elucidated for Ce(Ni0.61 Zn0.39 )2 Si2 and La(Ni0.56 Zn0.44 )2 Si2 . Ce(Ni0.61 Zn0.39 )2 Si2 exhibits a Kondo-type ground state. Low temperature specific heat data of La(Ni0.56 Zn0.44 )2 Si2 suggest a spin fluctuation scenario with an enhanced value of the Sommerfeld constant.