Crystal structure peculiarity and magnetic behavior of R2Cu4−xSn5+x (R = Gd, Tb, and Dy) compounds

The Gd2Cu3Sn6, Tb2Cu3.5Sn5.5, and Dy2Cu3.5Sn5.5 intermetallic compounds were prepared by arc melting, annealed at 670 K and characterized by XRPD and DSC analyses. Rietveld refinement showed that they crystallize in tetragonal Sm2Cu4Sn5 structure type (space group I4mm). The magnetic properties were studied in the temperature range 2–300 K and showed that in the paramagnetic state all studied compounds are Curie–Weiss paramagnets, among them Tb2Cu3.5Sn5.5 and Dy2Cu3.5Sn5.5 order antiferromagnetically at low temperatures and exhibit a metamagnetic transition. Electronic structure calculations were performed to evaluate chemical bonding.

Research highlights
► The R2Cu4−xSn5+x (0 ≤ x ≤ 1) compounds with R = Gd, Tb, and Dy crystallize in Sm2Cu4Sn5 structure type.
► According to DSC analysis investigated stannides exist in limited temperature range.
► All investigated compounds are Curie–Weiss paramagnets (2–300 K) among them Tb2Cu3.5Sn5.5 and Dy2Cu3.5Sn5.5 order antiferromagnetically and exhibit a metamagnetic transition.
► High electron density localization was observed between Sn–Sn and Cu–Sn atoms.