Energy down conversion phosphors represented by the chemical formula Ca1+xSr1−xGayIn2−ySzSe3−zF2 where (0≦x≦1, 0≦y≦2, 0≦z≦3) doped with rare earth and/or transition metal elements is disclosed. Dopant impurities may be one or more species such as Eu, Ce, Mn, Ru, and/or mixtures thereof present as activators. The molar fractions x, y and z, the dopant species and the dopant concentration may be varied to tune the peak emission wavelength and/or the width of the emission peak.