An experimental study of phosphorous and aluminosilicate speciation in and partitioning between aqueous fluids and silicate melts determined in-situ at high temperature and pressure

The structure of phosphorus-bearing, H2O-saturated silicate melts, silicate-saturated aqueous fluids, and silicate-rich single phase (supercritical) liquids has been characterized in situ to 800 degrees C and 1486 MPa in an Ir-gasketed hydrothermal diamond-anvil cell (HDAC) with the aid of both confocal microRaman and FTIR spectroscopy. Temperature and pressure in the HDAC were recorded with thermocouples (+/- 1 degrees C uncertainty) and pressure- and temperature-dependent Raman shift of C-13 diamonds (+/- 40 MPa uncertainty). Starting materials were aluminum-free Na2O center dot 4SiO(2) (NS4) and with 10 mol% Al2O3 (NA10) substituting for SiO2, both with 5 mol% P2O5.