Novel aluminum-silicate based orange-red phosphors, with mixed di- and trivalent cations are disclosed. The phosphors have the formula (Sr.sub.1-x-yM.sub.xT.sub.y).sub.3-mEu.sub.m(Si.sub.1-zAl.sub.z)O.sub.5, where M is at least one of Ba, Mg, Ca, and Zn in an amount ranging from 0.ltoreq.x.ltoreq.0.4. T is a trivalent metal in an amount ranging from 0.ltoreq.y.ltoreq.0. This phosphor is configured to emit visible light having a peak emission wavelength greater than about 580 nm. The phosphors may contain a halogen anion such as F, Cl, and Br, at least some of which is substitutionally positioned on oxygen lattice sites. The present aluminum-silicate phosphors have applications in white and orange-red illumination systems, as well as plasma display panels.