A phosphor of formula I is included in a phosphor composition in a lighting apparatus capable of emitting white light, Ca.sub.3-x-zSr.sub.xCe.sub.zM.sup.1.sub.2M.sup.2AlSiO.sub.12 (I) wherein M.sup.1 is Hf, Zr, or a combination thereof; M.sup.2 is Al, or a combination of Al and Ga; z<3-x; and 0.2>x.gtoreq.0. The lighting apparatus includes a semiconductor light source in addition to the phosphor composition.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
This invention was made with Government support under contract number DE-FC26-06NT42934 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.