strontiumaluminaten

Strontium aluminates are inorganic compounds composed of strontium, aluminum, and oxygen. The principal member is strontium aluminate, SrAl2O4, but related compositions such as Sr4Al14O25 and various doped variants are studied for their luminescent properties. In their undoped form, these materials are white powders, while doped forms act as phosphors.

A key feature of strontium aluminates is persistent luminescence. When doped with rare-earth ions such as europium (Eu2+) and dysprosium (Dy3+), they can emit light for extended periods after the excitation source is removed, typically in the green spectral region around 520–550 nm. The long afterglow results from electron traps created by the co-dopants in the host lattice; released electrons gradually excite luminescent centers, producing prolonged emission.

Synthesis usually involves high-temperature solid-state reactions from precursors such as SrCO3 and Al2O3 with dopants like Eu2O3 and Dy2O3. Firing temperatures commonly range from about 1100 to 1600°C, often in air or a reducing atmosphere to maintain the desired oxidation state of europium. Alternative methods, including sol–gel and combustion synthesis, are used to control particle size and morphology.

Applications of strontium aluminates center on their phosphorescent properties. They are widely used in glow-in-the-dark signage, safety markings, watch dials, novelty items, and emergency lighting. The material’s brightness and afterglow duration depend on composition, dopant levels, and synthesis conditions. Strontium aluminates are valued for relatively high brightness, good stability, and long-lasting emission compared with earlier phosphor systems.