Strontium aluminate is an aluminate compound with the chemical formula SrAl2O4 (sometimes written as SrO·Al2O3). It is a pale yellow, monoclinic crystalline powder that is odourless and non-flammable. When activated with a suitable dopant (e.g. europium, written as Eu:SrAl2O4), it acts as a photoluminescent phosphor with long persistence of phosphorescence. Strontium aluminates exist in a variety of other compositions including SrAl4O7 (monoclinic), Sr3Al2O6 (cubic), SrAl12O19 (hexagonal), and Sr4Al14O25 (orthorhombic). The different compositions cause different colours of light to be emitted.