Carbonate liquids are characterised by low temperature and low viscosity and play an important role in molten carbonate fuel cells, battery electrolytes and, surprisingly, in volcanic processes. Indeed they are important agents of element transfer in the deep Earth interior. Despite their unique role determined by structure-related properties little is known about the carbonate liquid structure. The aim of this work is to determine what happens to the carbonate chains when pressure is applied. We have recently completed an experiment on carbonate glasses at 3.3 and 8.5GPa. Ultrasonic measurements suggest a sudden change in the sound velocity in this region and in this proposal we will further explore this regime where structures change most by collected diffraction data for a pressure point at 6GPa. This will be augmented by simulation and NMR measurements.