Investigation of liquid-liquid transitions (LLT) in the As-P binary system: influence of the melt density on LLT

Examples of first-order transition in the liquid state remain scarce, and this phenomena is poorly understood. A well characterized system is liquid P, where a liquid-liquid transition (LLT) with a 40% density jump occurs around 1 GPa-1300K [1,2,4]. Here we propose to determine how the melt density influences the occurrence of a LLT by investigating the As-P binary system which provides a unique opportunity to vary the density in a nearly continuous fashion. This proposal thus aims at measuring the density and structure factor of the liquid phases of AsxP1-x alloys with x=0.05, 0.1 in order to determine : 1) how the addition of As affects the LLT in liquid P; 2) determine the influence of the melt density on the LLT. For this purpose we will use our well-established methods for studies of liquids under extreme conditions based on x-ray diffraction, absorption and radiography of samples confined in the Paris-Edinburgh press.