Abstract: Lithium-ion-conducting ceramic materials are disclosed having characteristics of high lithium-ion conductivity at low temperatures, good current efficiency, and stability in water and corrosive media under static and electrochemical conditions. Some general formulas for the lithium-ion-conducting materials include MI1+x+z??MIIIxMIVayMIVb2?x?yMVzP3?zO12 and MI1+x+4z??MIIIxMIVayMIVb2?x?y?zP3O12, wherein MI comprises Li, Na, or mixtures thereof; 0.05<x<0.5, 0.05<y<2, 0?z<3, and 0??<0.5; MIII comprises Al, Hf, Sc, Y, La, or mixtures thereof; MIVa comprises Zr, Ge, Sn, or mixtures thereof; MIVb comprises Ti; and MV comprises Si, Ge, Sn, or mixtures thereof. In some cases, the lithium-ion conducting materials are formed through a process in which the materials' powdered precursors are milled after being calcined and before being sintered. The milling process may include using milling media of multiple sizes.

Abstract: Lithium-ion-conducting ceramic materials are disclosed having characteristics of high lithium-ion conductivity at low temperatures, good current efficiency, and stability in water and corrosive media under static and electrochemical conditions. Some general formulas for the lithium-ion-conducting materials include MI1+x+z-?MIIIxMIVayMIVb2-x-yMVzP3-zO12 and MI1+x+4z-?MIIIxMIVayMIVb2-x-y-zP3O12, wherein MI comprises Li, Na, or mixtures thereof; 0.05<x<0.5, 0.05<y<2, 0?z<3, and 0??<0.5; MIII comprises Al, Hf, Sc, Y, La, or mixtures thereof; MIVa comprises Zr, Ge, Sn, or mixtures thereof; MIVb comprises Ti; and MV comprises Si, Ge, Sn, or mixtures thereof. In some cases, the lithium-ion conducting materials are formed through a process in which the materials' powdered precursors are milled after being calcined and before being sintered. The milling process may include using milling media of multiple sizes.