Pressure dependence of the structure of liquid copper halides

Abstract

X-ray diffraction of liquid CuI, CuBr and CuCl has been measuredup to 19 GPa using synchrotron radiations. Static structure factorS(Q) and pairdistribution function g(r) were obtained. For liquid CuI, CuBr and CuCl,S(Q) and g(r) change their shapes continuously with increasing pressure, indicating anisotropiccompression of the local structures. The pressure dependence of the peak position ratior2/r1 ofg(r) shows that Cu atoms are located in a tetrahedral site at low pressures and then in anoctahedral site at high pressures in these liquid copper halides. At higher pressures, thelocal structure of liquid CuCl is similar to the intermediate structure between NaCl andCsCl structures. These results are compared with the pressure-induced structuraltransformation in the crystalline phase.