Disclosed herein are emissive ceramic elements having low amounts of certain trace elements. Applicants have surprisingly found that a lower internal quantum efficiency (IQE) may be attributed to specific trace elements that, even at very low amounts (e.g., 50 ppm or less), can cause significant deleterious effects on IQE. In some embodiments, the emissive ceramic element includes a garnet host material and an amount of Ce dopant. The emissive ceramic element may, in some embodiments, have an amount of Na in the composition less than about 67 ppm, an amount of Mg in the composition less than about 23 ppm, or an amount of Fe in the composition less than about 21 ppm.