Macroscopic Separation of Dense Fluid Phase and Liquid Phase of Phosphorus

Katayama, Yoshinori; Inamura, Yasuhiro*; Mizutani, Takeshi*; Yamakata, Masaaki*; Utsumi, Wataru; Shimomura, Osamu*

Structural transformation between two liquid structures of phosphorus that occurred at about 1 GPa and 1000C was investigated by in-situ X-ray radiography. When the low-pressure liquid was compressed, dark and round objects appeared in the radiograph. X-ray diffraction measurements confirmed that these objects were the high-pressure liquid. The drops grew and eventually filled the sample space. Decompressing caused the reverse process. The macroscopic phase separation supported the view that it was a first-order liquid-liquid phase transition. X-ray absorption measurements revealed that the change in density at the transition is about 40 % of the density of the high-pressure liquid.