The Si-Sr and Si-Ba phase diagrams over the Si-rich composition range

For the first time, Si-Sr and Si-Ba phase diagrams have been investigated over the Si-rich composition range. The solid solubilities of Sr and Ba impurity getters in silicon were measured in the temperature range from 1173 to 1573 K by analytical methods, including microhardness and instrumental neutron activation analysis. The liquidus curves for the primary crystallization of silicon were determined by differential thermal and activation analyses. The alloys were prepared from pure components using induction heating with subsequent quenching. The samples were subjected to isochronous homogenization annealing at different temperatures for 100 h. The elements Sr and Ba exhibit retrograde solubility in silicon. The maximum equilibrium solubility of Sr in Si is 1.15 at.% at 1573 K, while the Ba solubility limit is 0.98 at the same temperature. The thermodynamic description of the experimental liquidus curves for the primary crystallization of Si indicates that the Si-Sr and Si-Ba liquid alloys do not inherently have a regular nature. We expect that the clathrate structure can exist in the Si-rich melts of the Si-Sr and Si-Ba systems.