Construction of the Sample Holder and Small-Angle X-ray Scattering Measurement for Supercritical Water

Abstract

A high-temperature and high-pressure sample holder suitable for water under supercritical conditions was constructed for small-angle X-ray scattering experiments, which was designed to endure the temperature up to 750 K and the pressure up to 40 MPa. By use of the holder, preliminary experiments for supercritical water were carried out along the isotherm at 663 K with pressures from 22.5 to 29.5 MPa. Isothermal change of the correlation length obtained from the scattering data showed maximum near the critical isochore. The tendency is similar to other supercritical fluids, e.g. , carbon dioxide, trifluorometane and ethylene.