Magnetic structure and thermodynamic properties of TmPtIn

Physical properties of TmPtIn have been investigated by means of magnetic, electrical transport, calorimetric as well as neutron diffraction measurements. The compound crystallizes in the hexagonal ZrNiAl-type crystal structure. It orders antiferromagnetically below T_N = 3.5 K with the Tm magnetic moments confined to the basal hexagonal plane. They form a non-collinear “triangular” magnetic structure that may be described by the propagation vector . At 1.6 K, the Tm magnetic moment is equal to 5.59(9)μ_B. The antiferromagnetic character of the electronic ground state is reflected in the low temperature behaviors of the magnetic susceptibility and the specific heat, which may be described by spin-wave theory of antiferromagnetic magnons with linear dispersion relation. The compound exhibits metallic character of electrical conduction.     

Three-dimensional characterization of fatigue-relevant intermetallic particles in high-strength aluminium alloys using synchrotron X-ray nanotomography

Second-phase particles and small porosities are known to favour fatigue crack initiation in high-strength aluminium alloys 2050-T8 and 7050-T7451. Using high-resolution X-ray tomography (320 nm voxel size), with Paganin reconstruction algorithms, the probability that large clusters of particles contain porosities could be measured for the first time in 3D, as well as precise 3D size distributions. Additional holotomography imaging provided improved spatial resolution (50 nm voxel size), allowing to estimate the probability of finding cracked particles in the as-received material state. The extremely precise 3D shape (including cracks) as well as local chemistry of the particles has been determined. This experiment enabled unprecedented 3D identification of detrimental stress risers relevant for fatigue in as-received aluminium alloys.     

Synthesis and crystal structures of La3MgBi5 and LaLiBi2

Two new ternary bismuthides, La₃MgBi₅ and LaLiBi₂, have been prepared by solid-state reactions of the corresponding pure metals in welded niobium tubes at high temperature. Their structures have been established by single-crystal X-ray diffraction studies. La₃MgBi₅ crystallizes in the hexagonal space group P6₃/mcm (No.193) with cell parameters of , , , and Z=2. LaLiBi₂ belongs to tetragonal space group P4/nmm (No.129) with cell parameters of , ,, and Z=2. The structure of La₃MgBi₅ is of the ‘‘anti’’ Hf₅Sn₃Cu type, and features 1D linear Bi⁻ anionic chains and face-sharing [MgBi_6/2]⁷⁻ octahedral chains. The structure of LaLiBi₂ is isotypic with HfCuSi₂, and is composed of 2D Bi⁻ square sheets and 2D LiBi layers with La³⁺ ions as spacers. Band calculations indicate that both compounds are metallic.     

Sm2NiSn4: The intermediate structure type between ZrSi2 and CeNiSi2

A new rare earth nickel stannide, Sm₂NiSn₄, has been prepared by reacting the pure elements at high temperature in welded tantalum tubes. Its crystal structure was established by single crystal X-ray diffraction studies. Sm₂NiSn₄ crystallizes in the orthorhombic space group Pnma (No. 62) with cell parameters of a=16.878(2) Å, b=4.4490(7) Å, c=8.915(1) Å, and Z=4. Its structure can be viewed as the intermediate type between ZrSi₂ and CeNiSi₂. Sm₂NiSn₄ features two-dimensional (2D) corrugated [NiSn₄]⁶⁻ layers in which the 1D Sn zigzag chains and the 2D Sn square sheets are bridged by Ni atoms. The Sm³⁺ cations are located at the interlayer space. Results of both resistivity measurements and extended-Hückel tight-binding band structure calculations indicate that Sm₂NiSn₄ is metallic.