Effect of pressure and temperature on self-diffusion coefficients in several concentrated deuterium oxide diamagnetic electrolyte solutions

The pressure dependences of the self-diffusion coefficients of deuterium oxide in 4.5 m solutions of LiCl--D2O and CsCl--D2O (also 7 m) and 3.06 m CaCl2--D2O have been measured by the NMR spin-echo method at 300C, 600C, and 900C. Shear viscosities and densities of these solutions have also been determined over the same range of experimental conditions. The experimental data show that the diffusion constant D decreases with the increasing structure-making ability of the electrolyte cation Ca2+ greater than Li+. In contrast, the diffusion coefficient for D2O in the 4.5 and 7 m CsCl solutions is equal to that for pure D2O at 300C but lower at 600C and 900C. It has been found that the Stokes--Einstein equation relates well the diffusion coefficients to shear viscosity in these concentrated electrolyte solutions