US20140080019A1
University of Texas System
The disclosure provides a material with the general formula Sr 1-x A x Si 1-y Ge y O 3-0.5x , wherein A is K or Na, including mixtures thereof, and wherein 0≦y≦1 and 0≦x≦0.4. In a specific embodiment, 0≦y≦0.5. In another specific embodiment, 0≦y≦0.1 and 0≦x≦0.4. In another specific embodiment 0.9≦y≦1 and 0≦ …