Patent ID: 8591758

Claim:
A method of making a substantially phase pure compound of Formula I, wherein A is a cation selected from the group consisting of Na, K, Rb, Mg, Ca, Sr, and Ba, and combinations thereof, and X is an anion selected from the group consisting of Si, Ge, and Sn, and combinations thereof, wherein the compound of Formula I is charge neutral, the method comprising: mixing a stoichiometric amount of anion X and a first amount of cation A in a ball-milling device, wherein the first amount of cation A is less than a stoichiometric amount of cation A, thereby consuming substantially all of the first amount of cation A and a first portion of anion X that is less than the stoichiometric amount of anion X to form a mixture of AX and unreacted X; and mixing a second amount of cation A with the unreacted X and the AX in the ball-milling device, wherein the second amount of cation A is less than the stoichiometric amount of cation A, thereby consuming substantially all of the second amount of cation A and a first amount of unreacted X, to afford substantially phase pure AX.