Structure and Properties of the Stannides CeAuSn, Ce₃Rh₄Sn₁₃, and Ce₃Ir₄Sn₁₃

Abstract

CeAuSn, Ce3Rh4Sn13, and Ce3lr4Sn13 were prepared by reaction of the elements in an arc-melting furnace and subsequent annealing at 970 K for two weeks. The three stannides were investigated by X-ray powder and single crystal techniques. CeAuSn crystallizes with the NdPtSb type, space group P63mc: a = 472.7(2), c = 771.6(3) pm, wR2 = 0.0230,208 F2 values, 11 variable parameters, and BASF = 0.40(2). The gold and tin atoms form a pronounced two-dimensional [AuSn] polyanion which consists of slightly puckered Au3Sn3 hexagons. ,19Sn Mössbauer data at 78 K show one signal at an isomer shift of δ = 1.90(7) mm/s subjected to unresolved quadrupole splitting of ΔEQ = 0.55(2) mm/s. Ce3Rh4Sn13 and Ce3lr4Sn13 adopt the cubic Yb3Rh4Sn13 type structure, space group Pm3n: a = 970.51(3) pm, wR2 = 0.0721, 267 F2 values (Ce3Rh4Sn13) and a = 972.29(6) pm, wR2 = 0.0850, 267 F2 values (Ce3lr4Sn13) with 14 variable parameters for each refinement. Striking structural motifs in Ce3Rh4Sn13 are condensed distorted trigonal [RhSn6] prisms with Rh-Sn distances of 266 pm. The polyhe­dral network leaves two different cages which are occupied by cerium (6c position) and tin (2a position) atoms. The Sn2 atoms show occupancy parameters of only 92% (Ce3Rh4Sn13) and 76% (Ce3Ir4Sn13) and an extremely large displacement parameter indicating a rattling of these atoms within the icosahedral Sn12 cages. Magnetic susceptibility measurements of Ce3Rh4Sn13 show paramagnetic behavior down to 2 K with an experimental magnetic moment of 2.45(2) μB/Ce. No magnetic ordering is observed. Magnetization measurements show a moment of 0.78(2) μB/Ce at 2 K and 5.5 T. Resistivity data reveal only a very weak tem­perature dependence. The two crystallographically different tin sites are resolved in the 119Sn Mössbauer spectrum which shows a signal at δ = 2.12(1) mm/s subject to quadrupole splitting of 1.54(1) mm/s, superimposed by a singlet at δ = 2.47(1) mm/s. The Seebeck coefficient of Ce3Rh4Sn13 is within a few μ V/K of zero over the temperature range of 10 - 300 K.

Ferromagnetic Ordering in CeZnSn

“…Prominent examples for this structural arrangement are the antimonide CeNiSb [6] or the germanide CeCuGe [7] with planar Ni 3 Sb 3 and Cu 3 Ge 3 nets, respectively. Similar atomic arrangements occur for the NdPtSbtype [8] compounds CeAuGe [9] and CeAuSn [10,11], which consist of slightly puckered Au 3 Ge 3 and Au 3 Sn 3 hexagons. Most CeT X representatives in the AlB 2 -related structural family adopt the orthorhombic TiNiSi-type structure [12].…”

“…In the minimal ASW basis set, the outermost shells were chosen to represent the valence states using partial waves up to l max + 1 = 4 for Ce, l max + 1 = 3 for Zn and Sn. From preliminary calculations assuming Zn 3d 10 states as part of the valence band, these states were found strongly localized at low energy (∼ −8 eV) with a filling close to 10 electrons, meaning that they do not intervene in the chemical bonding. This led us to consider them as core states in the subsequent calculations.…”

Crystal growth, transport, and magnetic properties of Ln3Co4Sn13 (Ln=La, Ce) with a perovskite-like structure

“…Data were corrected for extinction and refined with anisotropic atomic displacement parameters. To accurately determine the composition of our compounds, the occupancy parameters were refined in separate sets of least-squares cycles, since [20]. Unlike the Rh and Ir analogues, the Sn1 sites in Ln 3 Co 4 Sn 13 (Ln ¼ La, Ce) are fully occupied.…”

Electronic, magnetic, and electric transport properties of Ce3Rh4Sn13and CeŚlebarski1, White2, Fijałkowski3 et al. 2012Phys. Rev. B

“…The Sn2 atoms form a M (Sn2) 6 trigonal prism which are arranged in a three-dimensional network containing two different cages: one occupied by Ce (Ce(Sn2) 12 ) and the other by the Sn1 (Sn1(Sn2) 12 ) atoms. X-ray diffraction measurements have suggested the possibility of local vibrations of Sn atoms inside the cage, 7 which can lead to the rattling effect responsible for the low phonon thermal conductivities found in filled cage compounds. The efficiency of thermoelectric devices is characterized by the thermoelectric figure-of-merit ZT = S 2 σT /κ, where S is the Seebeck coefficient (or thermopower), σ is the electrical conductivity, and κ is the total thermal conductivity with contributions from electrons and the lattice.…”

“…The thermopower of Ce 3 Rh 4 Sn 13 is weakly temperature dependent and small. 5,7 (ii) Heavy fermion compound Ce 3 Ir 4 Sn 13 orders antiferromagnetically and demonstrates an intriguing double peak feature in the specific heat at 2.1 and 0.6 K. 6 On the other hand, low-temperature neutron diffraction results 8,9 and specific heat measurements 3,5 show no evidence for long-range magnetic order in either Ce 3 Co 4 Sn 13 or Ce 3 Rh 4 Sn 13 ; although there is evidence for two magnetic phase transitions at 1.2 and 2 K in the heat capacity data reported for the Rh-sample. 10 Recently, our theoretical simulation of vacancies at the 2a sites revealed, within the virtual crystal approximation (VCA), that the magnetic ground state of Ce 3 Rh 4 Sn 13 is very sensitive to the Sn content.…”