Abstract: New dual temperature electrochemical methods and systems for the production of sodium metal from sodium polysulfides have been discovered. The technology provides high conductivity for sodium ions and extended service life for the electrochemical cell.

Abstract: New dual temperature electrochemical methods and systems for the production of sodium metal from sodium polysulfides have been discovered. The technology provides high conductivity for sodium ions and extended service life for the electrochemical cell.

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.

Abstract: A method for producing an alkali metal hydroxide, comprises providing an electrolytic cell that includes at least one membrane having ceramic material configured to selectively transport alkali metal ions. The method includes introducing a first solution comprising an alkali metal hydroxide solution into a catholyte compartment such that said first solution is in communication with the membrane and a cathode. A second solution comprising at least one alkali metal salt and one or more monovalent, divalent, or multivalent metal salts is introduced into an anolyte compartment such that said second solution is in communication with the membrane and an anode. The method includes applying an electric potential to the electrolytic cell such that alkali metal ions pass through the membrane and are available to undertake a chemical reaction with hydroxyl ions in the catholyte compartment to form alkali metal hydroxide.

Abstract: Metal ion conducting ceramic materials are disclosed having characteristics of high ion conductivity for certain alkali and monovalent metal ions at low temperatures, high selectivity for the metal ions, good current efficiency and stability in water and corrosive media under static and electrochemical conditions. The metal ion conducting ceramic materials are fabricated to be deficient in the metal ion. One general formulation of the metal ion conducting ceramic materials is Me1+x+y?zMIIIyMIV2?ySixP3?xO12?z/2, wherein Me is Na+, Li+, K+, Rb+, Cs+, Ag+, or mixtures thereof, 2.0?x?2.4, 0.0?y?1.0, and 0.05?z?0.9, where MIII is Al3+, Ga3+, Cr3+, Sc3+, Fe3+, In3+, Yb3+, Y3+, or mixtures thereof and MIV is Ti4+, Zr4+, Hf4+, or mixtures thereof.

Abstract: Pressureless sintering of silicon carbide with fracture toughness in excess of about 4 MPa-m1/2 as measured by the single-edge precracked beam (SEPB) technique while maintaining a density greater than 3.1 g/cc for compositions with SiC greater than about 94 wt. % is made possible through the use of metallic Al to promote sintering and grain growth. Boron and carbon may be used as traditional sintering aids, with nitrogen to suppress grain growth, and additions of yttrium and/or lanthanide elements to promote intergranular fracture.

Abstract: Metal ion conducting ceramic materials are disclosed having characteristics of high ion conductivity for certain alkali and monovalent metal ions at low temperatures, high selectivity for the metal ions, good current efficiency and stability in water and corrosive media under static and electrochemical conditions. The metal ion conducting ceramic materials are fabricated to be deficient in the metal ion. One general formulation of the metal ion conducting ceramic materials is Me1+x+y?zMIIIyMIV2?ySixP3?xO12?z/2, wherein Me is Na+, Li+, K+, Rb+, Cs+, Ag+, or mixtures thereof, 2.0?x?2.4, 0.0?y?1.0, and 0.05?z?0.9, where MIII is Al3+, Ga3+, Cr3+, Sc3+, Fe3+, In3+, Yb3+, Y3+, or mixtures thereof and MIV is Ti4+, Zr4+, Hf4+, or mixtures thereof.

Abstract: A method is provided to recycle and synthesize aqueous alkali chemicals from industrial and radioactively contaminated alkali salt based waste streams using a two-compartment electrolytic cell having an alkali cation-conductive ceramic membrane. The processes and apparatus provide the capability of recycling and synthesizing value added chemicals, including but not limited to, alkali hydroxides.

Abstract: Pressureless sintering of silicon carbide with fracture toughness in excess of about 4 MPa-m1/2 as measured by the single-edge precracked beam (SEPB) technique while maintaining a density greater than 3.1 g/cc for compositions with SiC greater than about 94 wt. % is made possible through the use of metallic Al to promote sintering and grain growth. Boron and carbon may be used as traditional sintering aids, with nitrogen to suppress grain growth, and additions of yttrium and/or lanthanide elements to promote intergranular fracture.