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Characterisation
The obtained nanowires were characterized using the Hitachi 5500a scanning electron microscope operating at 30 kV and a JEOL 2010-FEF Transmission Electron Microscope operating at 200kV, equipped with an Omega filter. The nanowires were sonicated in Ethanol and transferred onto carbon grids supported by copper or gold grids for TEM observation. The transfer to TEM was made in less than 20 min to avoid oxidation of the nanowires. Before FFT analysis of the HTREM images, the microscope have been previously calibrated using bulk crystalline Si I samples. The EDX measurements were obtained from nanowires deposited on gold TEM grids. This explains the detection of traces of gold in EDX spectra. The elemental maps were recorded by Energy-Filtered TEM imaging thanks to the omega-filter. Silicon, oxygen and copper maps are obtained by using an energy selecting slit positioned around the energy-losses of the edges : Si L_2,3 (99 eV), O K (532 eV) and Cu L_2,3 (931 eV).
X-ray diffraction experiments have been performed on a PANalytical Xpert Pro MRD diffractometer, equipped with a Cu anode in line focus. The upstream optic is a graded W/Si mirror. The equatorial beam divergence is 0.03° and the beam footprint on the sample is defined by a fixed slit of 0.8 mm in the equatorial plane and 10 mm in the vertical plane. The diffracted peaks are registered on a linear detector (PIXcel) used in scanning mode. The instrumental broadening is 0.1°. An offset of 2° is applied in order to decrease the intensity of the 004 substrate reflection. The measurement is performed in θ-2θ mode.

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