Cu3Si is used as a catalyst for the production of technologically highly important chlorosilanes, an intermediate compound in the production of ultrapure silicon for the semiconductor industry [1]. Copper silicides and copper germanides have also been studied as materials for applications as contacts and interconnects in Si and Ge-Si electronic devices [2]. Different structures of Cu3Si and Cu3(SiGe) have been reported over the years [3,4,5], however, new aspects have been revealed by this study.
Nanoobjects of various shapes were prepared by the CVD method using organometallic precursors (SiH4, EtSiH4, BuSiH3, and their mixtures with H2) and copper substrates at temperature of about 500 °C. For comparison and more variability in composition, bulk samples of various compositions (Cu78Si22, Cu77Si23, Cu76Si24, Cu75Si25, Cu74Si26) were prepared by arc melting.
Samples were screened by SEM/EDX/EBSD and powder XRD. Selected samples were studied by single-crystal XRD and TEM. TEM was performed on a Philips CM 120 (LaB6, 120kV) equipped with a NanoMEGAS precession unit DigiStar, an Olympus SIS CCD camera Veleta (2048×2048), and an EDAX windowless EDX detector Apollo XLTW. Precession-assisted electron diffraction tomography (EDT) in microdiffraction setup was used to acquire data for structure characterization of nanoobjects.
In the Cu3Si solid solution (Fig. 1), two variants were identified sharing the same average structure (P63/mmc, a=4.06Å, c =14.66Å). The structures of the two variants (diagonal (D) and off-diagonal (O)) differ in the placement of satellite reflections, which are caused by strong modulation of the honeycomb copper layers. The D and O variants are most likely stabilized by composition. The D-variant was observed in bulk sample with composition of Cu77Si23 and also in the nanoplatelets prepared by CVD on Cu-substrates, whereas the O-variant was present in the samples richer in silicon. Moreover, additional periodicity along c-axis was detected in Cu3Si compared to Cu3(SiGe) with c=7.33Å (Fig. 2). Temperature experiments are currently under progress, and will be also presented.
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[5] Palatinus, L.; Klementová, M.; Dřínek, V.; Jarošová, M.; Petříček, V., Inorg. Chem. 2011, 50, 3743–3751.
[6] The study was supported by the Czech Science Foundation under project No. 15-08842J.
Figures:
Fig. 1: (a) Cu3Si structure viewed along [100] - Cu - black, Si - light grey. (b) Strongly modulated honeycomb layer filled with copper atoms results in diagonal and off-diagonal variants of the structure.
Fig. 2: Sections through reciprocal space acquired from EDT data of (a) Cu3Si nanowire prepared by CVD, (b) Cu¬3(SiGe) nanoplatelet prepared by CVD.
To cite this abstract:
Klementová Mariana, Cinthia Correa, Vladislav Dřínek, Petr Brázda, Jaromír Kopeček, Lukáš Palatinus; New phases in Cu3Si solid solution. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/new-phases-in-cu3si-solid-solution/. Accessed: December 4, 2023« Back to The 16th European Microscopy Congress 2016
EMC Abstracts - https://emc-proceedings.com/abstract/new-phases-in-cu3si-solid-solution/