Hydrogen transport in lithium hydride as a function of pressure

The exchange process for the reaction between deuterium gas and lithium hydride single crystals has been studied as a function of deuterium pressure over the range 32–555 torr at 465°C. The kinetic data could be fit best by considering the rate of the exchange process to be controlled by the diffusion of D⁻. By using solutions to Fick's second law and considering the surface concentration of D₂ to vary with pressure, the diffusion coefficients were found to be independent of pressure. The tracer diffusion coefficients thus found were ${\text{1.4 × 10}}^{\text{−9}}\hspace{0.17em}{\mathrm{cm}}^2\hspace{0.17em}{\sec }^{\text{−1}}$ for a one‐dimensional model and ${\text{1.9 × 10}}^{\text{−9}}\hspace{0.17em}{\mathrm{cm}}^2\hspace{0.17em}{\sec }^{\text{−1}}$ for a three‐dimensional model.