X-ray and neutron structure determination and magnetic properties of new quaternary phases RE0.67Ni2Ga5+n-xGex and RE0.67Ni2Ga5+n-xSix (n = 0, 1; RE = Y, Sm, Gd, Tb, Dy, Ho, Er, Tm) synthesized in liquid Ga

Marina A. Zhuravleva, X. Z. Chen, Xiaoping Wang, Arthur J. Schultz, John Ireland, Carl K. Kannewurf, Mercouri G. Kanatzidis*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


Liquid Ga was used as a solvent to explore the phase formation between rare-earth metals (REs), Ni, and a tetrelide (Tt = Si, Ge). The reactions were performed in excess liquid Ga at 850 °C. Two new phases of general formulas RE0.67Ni2Ga5-xTtx and RE0.67Ni2Ga6-xTtx were found and structurally characterized. The Co analogues of the latter RE0.67Co2Ga6-xGex (RE = Y, Gd) were also prepared. Single-crystal X-ray data: The first group of compounds RE0.67Ni2Ga5-xTtx crystallizes in the hexagonal space group P63/mmc with a structure related to the RE2-xPt4Ga8+y type (Sm0.53Ni2Ga5-xGex, a = 4.1748(7) Å, c = 16.007(4) Å, V = 241.61(8) Å3, Z = 2; Y0.59Ni2Ga5-xGex, a = 4.1344(11) Å, c = 15.887(6) Å, V = 235.18(12) Å3, Z = 2; Tb0.67Ni2Ga5-xSix, a = 4.1415(11) Å, c = 15.843(6) Å, V = 235.33(12) Å3, Z = 2; Ho0.67Ni2Ga5-xGex, a = 4.1491(4) Å, c = 15.877(2) Å, V = 236.71(5) Å3, Z = 2). The second group RE0.67Ni2Ga6-xTtx crystallizes in P6m2 (Gd0.67Ni2Ga6-xGex, a = 4.1856(10) Å, c = 9.167(3) Å, V = 139.08(7) Å3, Z = 1; SM0.67Ni2Ga6-xSix, a = 4.1976(8) Å, c = 9.159(3) Å, V = 139.76(5) Å3, Z = 1) in a structure related to the ErNi3Al9 structure type with disorder in the RE-Ga plane. Dy0.67Ni2Ga6-xGex crystallizes in space group P31c (a = 7.2536(8) Å, c = 18.308(3) Å, V = 834.21(2) Å3, Z = 6) with partial disorder in the RE-Ga plane. The structures of these two groups of compounds are related to each other and contain similar building motifs, namely Gan[NiGa2-x/2Gex/2]2 slabs and RE0.67Ga monatomic layers which alternate along the c-direction, forming a 3D structure. The parameter x and the position of the tetrelide in the structure were determined by single-crystal neutron diffraction. Complete or partial disorder of the RE and Ga atoms is observed in the RE-Ga plane. The origin of the disorder lies in the extensive and random stacking faults of ordered RE-Ga planes, which apparently slide easily in the ab plane and create an averaged disordered picture. Electrical conductivity and thermopower measurements indicate that these compounds are metallic conductors. The magnetic measurements show antiferromagnetic ordering at ∼3-4 K and Curie-Weiss behavior at higher temperatures with the values of μeff close to those of RE3+ free ions. Strong 2-fold crystal field anisotropy is observed for the heavy RE analogues. The anisotropy constants K2para calculated from the Weiss constant anisotropy for heavy RE analogues are reported.

Original languageEnglish (US)
Pages (from-to)3066-3081
Number of pages16
JournalChemistry of Materials
Issue number7
StatePublished - 2002

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry


Dive into the research topics of 'X-ray and neutron structure determination and magnetic properties of new quaternary phases RE<sub>0.67</sub>Ni<sub>2</sub>Ga<sub>5+n-x</sub>Ge<sub>x</sub> and RE<sub>0.67</sub>Ni<sub>2</sub>Ga<sub>5+n-x</sub>Si<sub>x</sub> (n = 0, 1; RE = Y, Sm, Gd, Tb, Dy, Ho, Er, Tm) synthesized in liquid Ga'. Together they form a unique fingerprint.

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