strontiumaluminat

Strontium aluminate, with the chemical formula SrAl2O4, is a crystalline host material used for persistent luminescence. It has gained prominence as a phosphor capable of emitting light long after the excitation source has been removed, when doped with suitable activators.

The most common dopant combination is europium in the divalent state (Eu2+) as activator and dysprosium (Dy3+) as a trap-inducing co-dopant. In SrAl2O4:Eu2+,Dy3+, exposure to ultraviolet or visible light promotes electrons into excited states that are later trapped and gradually released, yielding a green emission typically centered near 520 nm. The duration and brightness of the afterglow depend on dopant levels, particle size, and environmental conditions.

SrAl2O4 is typically prepared by high-temperature solid-state synthesis from precursors such as strontium carbonate and aluminum oxide, often with dopant oxides, under reducing or inert conditions to maintain Eu2+. The material is chemically stable and relatively resistant to moisture; it is also insoluble in water, making it suitable for use in paints, coatings, and luminescent applications.

Applications include glow-in-the-dark pigments for safety signage, emergency and compliance markings, novelty items, watches, and decorative paints. Its long afterglow and high brightness make it a preferred choice among persistent phosphors, often outperforming older calcium or zinc sulfide-based phosphors in duration and color stability.

Strontium aluminate phosphors were developed in the late 20th century and have since become widely studied for luminescent performance, stability, and dopant chemistry. As with all inorganic phosphors, handling should follow standard safety guidelines for powder materials.