A tale of two polymorphs-growth and characterization of α-LnNiGa 4 (Ln = Y, Gd-Yb) and β-LnNi1-xGa4 (Ln = Tb-Er)

Melissa C. Menard, Louisiana State University
Brenton L. Drake, Louisiana State University
Gregory T. McCandless, Louisiana State University
Kandace R. Thomas, Louisiana State University
Richard D. Hembree, Louisiana State University
Neel Haldolaarachchige, Louisiana State University
John F. Ditusa, Louisiana State University
David P. Young, Louisiana State University
Julia Y. Chan, Louisiana State University


The single crystals of two polymorphs of LnNiGa4, namely, the orthorhombic α-LnNiGa4 (Ln = Y, Gd-Yb) and, a new polymorph, the tetragonal β-LnNi1-xGa4 (Ln = Tb-Er), were successfully grown by using the self-flux method. α-LnNiGa4 (Ln = Y, Gd-Yb) is isostructural to YNiAl4 and can be described as an edge-sharing polyhedral of Ni@Ga7Ln2 (Ln = Y, Gd-Yb) along the ac-plane that is sandwiched between the square nets of the Ga atoms along the b-axis. The structure of β-LnNi1-xGa4 (Ln = Tb-Er) is a distorted variant of the Ce2NiGa10-structure type with a Ni deficiency and multiple Ga split positions and is structurally related to YNiGa3Ge. The magnetic data for β-LnNi 1-xGa4 (Ln = Tb-Er) and the transport properties for α-LnNiGa4 (Ln = Y, Gd-Tm) and β-LnNi1-xGa 4 (Ln = Tb-Er) are reported. Antiferromagnetic correlations are observed in the magnetic susceptibility of β-LnNi1-xGa 4 (Ln = Tb-Er), where the magnetic transitions occurred below 7 K and with effective moments that are consistent with free Ln3+ ions. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.