Patent ID: 8211400

Claim:
A method of synthesizing a clathrate compound 1, the method comprising the steps of: a) forming an intermediate Zintl compound in a nitrogen gas atmosphere; b) grinding the intermediate Zintl compound to a fine powder in an inert atmosphere; c) heating the ground intermediate Zintl compound through a first temperature of approximately 360° C. at a rate of approximately several hundred ° C/min; and d) heating the intermediate Zintl compound to a second temperature for a predetermined second duration of time to form a clathrate compound comprising a type II clathrate lattice with atoms of silicon and germanium as a main framework forming lattice spacings within the framework, wherein the clathrate lattice follows the general formula Si136−yGey, where y indicates the number of Ge atoms present in the main framework and 136−y indicates the number of Si atoms present in the main framework, and wherein y>0, wherein the second temperature determines the composition of the clathrate compound and the second duration of time determines a guest atom content within the lattice spacings of the clathrate compound.