The in-situ XAFS technique has been employed to study the local structures of semi-metal Sb in the pre-molten and liquid states. The results reveal that the local structure of the pre-molten Sb at the temperature of 893 K is similar to that of crystalline Sb at 298 K

except that the thermal disorder of the former is relatively larger. With the temperature increasing to 913 K ( melting point Tm= 903 K for the element Sb )

the main peak intensity of radial distribution function of the molten Sb ( 913 K) is strongly reduced to about 70% of the pre-molten Sb ( 893 K ) . This indicates that the structural disorder of the liquid Sb increases remarkably during the solid-liquid tran- sition

which can be attributed to the fact that the covalent bonds of the first shell are mostly broken in liquid Sb. The results obtained from the model-independent reverse Monte Carlo calculation in the process of solid-liquid transition shows that the coordination number of the first neighbor around Sb atoms increases from 6 to 9. As the temperature further rises to 1058 K

the radial structural function of Sb ( 1058 K ) indicates that liquid Sb possesses a similar local structure in the temperature range of 100—200 K beyond the melting point.