Apparatus for the Determination of Diffusion Coefficients in Fused Salts (NaNO3) at High Pressure

An apparatus for the determination of diffusion coefficients in fused salts at pressures up to 2 kbar, together with the necessary experimental techniques, is described. Values of the self-diffusion coefficients of 22Na in NaNO3 at 350°C are (2.10±0.09)×10−5 cm2 sec−1 at 1 bar, (1.90±0.05)×10−5 cm2 sec−1 at 400 bar, and (1.77±0.05)×10−5 cm2 sec−1 at 800 bar. The activation volume for the self-diffusion of 22Na in NaNO3 is 10.7±1.4 cm3 mole−1.