Fosforer

Fosforer, or phosphors, are luminescent inorganic compounds that emit light after absorbing energy. They are typically doped with activator ions such as europium, cerium, terbium, manganese, or other lanthanides within a host lattice made of oxides, sulfides, fluorides, silicates, aluminates, or borates. When excited by ultraviolet light, electrons in the dopant create energy levels within the band gap and release photons as they return to lower states. The emission color and persistence depend on the host material and dopant; some phosphors exhibit fast fluorescence, while others show long-lasting phosphorescence.

Common families include ZnS:Mn, SrAl2O4:Eu2+,Dy3+ for persistent phosphors, and Ce3+-doped garnets such as Y3Al5O12:Ce3+ used in white-light LEDs. In modern lighting, blue LEDs pump Ce3+-doped YAG to produce white light via down-conversion. Phosphors are also used in displays, scintillators for radiation detection, and various imaging and security applications.

Applications and significance: phosphors enable a wide range of lighting and display technologies, from fluorescent lamps to white LED sources, as well as legacy cathode-ray tubes and plasma displays. They also play a role in medical imaging and dosimetry, where scintillating phosphors convert high-energy radiation into visible light.

Synthesis and properties: phosphors are commonly prepared by solid-state reactions, co-precipitation, or hydrothermal methods. Particle size, crystal quality, and dopant levels influence brightness, color, and afterglow duration. Environmentally conscious development emphasizes cadmium-free compositions and alternatives with lower energy consumption and reduced toxicity.