Structure and Properties of YbZnSn, YbAgSn, and Yb2Pt2Pb

• Published in: Journal of solid state chemistry 1999-07, Vol.145 (2), p.668-677
• Main Authors: Pöttgen, Rainer, Arpe, Petra E, Felser, Claudia, Kußmann, Dirk, Müllmann, Ralf, Mosel, Bernd D, Künnen, Bernd, Kotzyba, Gunter
• Format: Article
• Language: English
• Subjects: 119Sn Mössbauer spectroscopy; Alloys; Applied sciences; chemical bonding; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Conductivity phenomena in semiconductors and insulators; crystal structure; Electronic transport in condensed matter; Exact sciences and technology; intermetallic compounds; Low-field transport and mobility; piezoresistance; Magnetic properties and materials; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Magnetically ordered materials: other intrinsic properties; Metals. Metallurgy; Mossbauer effect; other γ-ray spectroscopy; Mössbauer effect; other γ-ray spectroscopy; Physics; Saturation moments and magnetic susceptibilities; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; ytterbium
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.1998.8280

YbZnSn, YbAgSn, and Yb2Pt2Pb were synthesized by reacting the elements in sealed tantalum tubes in a high-frequency furnace. The structures of YbAgSn and Yb2Pt2Pb were refined from single crystal X-ray data: YbAgPb type, P6m2, a=479.2(2) pm, c=1087.3(3) pm, wR2=0.050, BASF=0.34(8), 509 F2 values, 18 variables for YbAgSn and Er2Au2Sn type, a=776.0(1) pm, c=701.8(2) pm, wR2=0.072, 426 F2 values, 18 variables for Yb2Pt2Pb. The lattice constants of YbZnSn are confirmed: NdPtSb type, P63mc, a=464.7(1) pm, c=747.7(2) pm. The stannides YbZnSn and YbAgSn crystallize with superstructures of the AlB2 type. The zinc (silver) and tin atoms form ordered Zn3Sn3 and Ag3Sn3 hexagons, respectively. The stacking sequences for the differently oriented hexagons are AB, AB for YbZnSn and ABC, ABC for YbAgSn. While exclusively Zn–Sn intralayer interactions were observed in YbZnSn, intralayer Ag–Sn and significant Sn–Sn interlayer interactions at 318 pm occur in YbAgSn. The [ZnSn] and [AgSn] polyanions in YbZnSn and YbAgSn, respectively, have a pronounced two-dimensional character. This picture of chemical bonding in YbAgSn is confirmed by TB–LMTO–ASA band structure calculations. The partial densities-of-states and the valence charge densities are discussed. The magnetic (no long-range ordering, Yb2+) and the resistivity measurements (metallic behavior) are in excellent agreement with the electronic structure calculations. Yb2Pt2Pb crystallizes with the Er2Au2Sn structure, a ternary derivative of the Zr3Al2 type. This structure is composed of distorted AlB2 and CsCl related slabs of compositions YbPt2 and YbPb. Yb2Pt2Pb shows paramagnetic behavior (4.3±0.4 μB/Yb) indicating trivalent ytterbium. Magnetic susceptibility measurements on YbZnSn and YbAgSn show Pauli paramagnetism with room temperature susceptibilities of 2.5(1)×10−9 and 4.6(1)×10−9 m3/mol. Electrical resistivity measurements indicate metallic conductivity with specific resistivities of 440±40 μΩcm (YbZnSn) and 490±40 μΩcm (YbAgSn) at 300 K. 119Sn Mössbauer spectra of YbZnSn show a single signal at room temperature with an isomer shift of δ=1.85(1) mm/s. YbAgSn shows two superimposed signals at 78 K: a singlet at δ=1.94(1) mm/s and a second signal at δ=1.99(1) mm/s subjected to quadrupole splitting of ΔEQ=1.35(1) mm/s, in agreement with the two crystallographically different tin sites.