Crystal structure of Cu-Sn-In alloys around the {\eta} phase field studied by neutron diffraction

The study of the Cu-Sn-In ternary system has become of great importance in recent years, due to new environmental regulations forcing to eliminate the use of Pb in bonding technologies for electronic devices. A key relevant issue concerns the intermetallic phases which grow in the bonding zone and are determining in their quality and performance. In this work, we focus in the {\eta}-phase (Cu2In or Cu6Sn5) that exists in both end binaries and as a ternary phase. We present a neutron diffraction study of the constitution and crystallography of a series of alloys around the 60 at.% Cu composition, and with In contents ranging from 0 to 25 at.%, quenched from 300\degreeC. The alloys were characterized by scanning electron microscopy, probe microanalysis and high-resolution neutron diffraction. The Rietveld refinement of neutron diffraction data allowed to improve the currently available model for site occupancies in the hexagonal {\eta}-phase in the binary Cu-Sn as well as in ternary alloys. For the first time, structural data is reported in the ternary Cu-Sn-In {\eta}-phase as a function of composition, information that is of fundamental technological importance as well as valuable input data for ongoing modelisations of the ternary phase diagram.Comment: 8 pages, 10 figure

Phase Identification of Cu-In Alloys with 45 and 41.25 at.% In Compositions

In this work, the thermal stability of Cu-In alloys with 45.0 and 41.2 at.% In nominal compositions was investigated by differential scanning calorimetry (DSC), scanning electron microscopy, wavelength dispersive spectroscopy, and in-situ synchrotron x-ray powder diffraction (S-PXRD) over a temperature range from 25 up to 400 °C. The studied samples are mainly composed of a Cu 11 In 9 phase together with minor amounts of the B phase (based on the NiAs Ni 2 In type structure) and, in one of the samples, with a minor amount of pure In. No evidence of the Cu 10 In 7 (41.2 at.% In) phase was detected, not even in the sample with 41.2 at.% In nominal overall composition. The combined use of the S-PXRD and DSC techniques allowed us to identify two phase transitions involving the Cu 11 In 9 phase, one of them corresponding to the g 0 Ð B þ Cu 11 In 9 reaction at T = 290 °C and the other to the peritectic g 0 þ L Ð Cu 11 In 9 reaction at T = 311 °C.Fil: Baque, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Technical University of Denmark; DinamarcaFil: Torrado, D.. Universidad Nacional del Comahue; ArgentinaFil: Aurelio, Gabriela. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lamas, Diego Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Aricó, Sergio Fabián. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Unidad de Actividad de Materiales (CAC); ArgentinaFil: Craievich, A. F.. Universidade de Sao Paulo; BrasilFil: Sommadossi, Silvana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue; Argentin

Synthesis, Structural Characterization, and Ab Initio Study of Cu(5+δ)In(2+x)Sb(2-x): A New B8-Related Structure Type.

A new ternary orthorhombic compound with the formula Cu(5+δ)In(2+x)Sb(2-x), crystallizing in the space group Cmc2(1) with 36 atoms per unit cell [a = 10.1813(4) Å, b = 8.4562(4) Å, c = 7.3774(2) Å, Z = 4], has been synthesized by conventional high-temperature methods. The structure is based on the B8 archetype (NiAs/Ni(2)In) and features In/Sb ordering as well as ordering of interstitial copper. Details of the experimental study and the structural parameters of this compound are reported in the first part of the work. In the second part, ab initio calculations based on the density functional theory and the projector augmented-wave method are used to characterize the structural, thermodynamic, and phase-stability properties of the new ternary phase. The present calculations include the lattice parameters, molar volume, bulk modulus and its pressure derivative, the energy of formation from the elements, and the electronic density of states. Moreover, the present ab initio method is used to investigate the thermodynamic properties of the anti-structure Cu(5)Sb(2)In(2) compound obtained by exchanging the In and Sb Wyckoff symmetric positions