The Stannides YNi_xSn₂ (x = 0, 0.14, 0.21, 1) – syntheses, structure, and ¹¹⁹Sn Mössbauer spectroscopy

Abstract

The stannides YNi_xSn₂ (x = 0, 0.14, 0.21, 1) were prepared by arc-melting of the pure elements. They were characterized through X-ray powder and single crystal data: ZrSi₂ type, space group Cmcm, a = 438.09(6), b = 1629.6(4), c = 430.34(7) pm, wR2 = 0.0607, 386 F² values, 14 variables for YSn₂, CeNiSi₂ type, Cmcm, a = 440.6(1), b = 1640.3(1), c = 433.0(1) pm, wR2 = 0.0632, 416 F² values, 19 variables for YNi0.142(7)Sn₂, a = 441.0(1), b = 1646.3(1), c = 434.6(1) pm, wR2 = 0.0491, 287 F² values, 19 variables for YNi_0.207(7)Sn₂, and LuNiSn₂ type, space group Pnma, a = 1599.3(3), b = 440.89(5), c = 1456.9(2) pm, wR2 = 0.0375, 1538 F² values, 74 variables for YNiSn₂. The YSn₂ structure contains Sn1–Sn1 zig-zag chains (297 pm) and planar Sn₂ networks (307 pm). The stannides YNi_0.142(7)Sn₂ and YNi_0.207(7)Sn₂ are nickel filled versions of YSn₂. The nickel atoms have a distorted pyramidal tin coordination with Ni–Sn distances ranging from 220 to 239 pm. New stannide YNiSn₂ adopts the LuNiSn₂ type. The nickel and tin atoms build up a complex three-dimensional [NiSn₂] network in which the yttrium atoms fill distorted pentagonal and hexagonal channels. Within the network all nickel atoms have a distorted square pyramidal tin coordination with Ni–Sn distances ranging from 247 to 276 pm. Except the Sn4 atoms which are located in a tricapped trigonal Y₆ prism, all tin atoms have between 4 and 5 tin neighbors between 297 and 350 pm. ¹¹⁹Sn Mössbauer spectroscopic data of YNi_xSn₂ show a decreasing isomer shift (from 2.26 to 2.11 mm/s) from YSn₂ to YNiSn₂, indicating decrease of the s electron density at the tin nuclei.