X-ray diffraction measurements for liquid Ge-Si alloys using synchrotron radiation

Energy dispersive X-ray diffraction measurements have been carried out for liquid Ge1-xSix alloys (x = 0.0, 0.3, 0.5, 1.0) using synchrotron radiation at SPring-8. We measured the X-ray diffraction spectra of liquid Ge and Si up to a high temperature range, (liquid Ge from 1270 to 1870 K and liquid Si from 1680 to 2020 K), liquid Ge0.7Si0.3 at 1620 K, and liquid Ge0.5Si0.5 at 1540, 1590, 1670 and 1720 K. The total structure factors of the liquid Ge-Si alloys have a characteristic shoulder on the high-wave-vector side of the first peak. We deduced a pair distribution function from the Fourier transform of the observed structure factor, which was weakly dependent on the temperature. The nearest-neighbor coordination number of liquid Ge-Si alloys is close to that of pure liquid Ge and Si. The first peak of the pair distribution function moved to a shorter distance with increasing Si concentration. These results may indicate that the atomic radii of the Si and Ge atoms in the pure liquid are preserved in the liquid alloys. (c) 2007 Published by Elsevier B.V.