High Temperature X-Ray Diffraction Study of Melt Structure of Silicon

The structure of molten silicon has been determined at three temperatures of 1440, 1460 and 1520° C by X-ray diffraction. All structure factors indicate a characteristic small hump on the higher wave vector side of the first peak and such specific feature becomes slightly obscure as the temperature increases. A small peak is found in the region between the first (0.245 nm) and second (0.55 nm) main peaks in the pair distribution functions with a shallow minimum at about 0.35 nm. This is not observed in the pair distribution functions for usual molten metals. The coordination numbers in the near-neighbor region have been estimated by applying the interference function refining technique and the results for the first two neighbors are 6.3 (4.6+1.7) at 1440° C, 5.7 (4.5+1.2) at 1460° C and 5.8 (4.4+1.4) at 1520° C. The present structural information is consistent with the recent results of density and electrical resistivity of molten silicon.