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Copper‐doped corundum (α‐Al2O3) possesses an intense broadband photoluminescence in the near infrared. This photoluminescence is originated from Cu2+ ions, which substitute for Al3+ ions in corundum lattice. Co‐doping with Ge is necessary to obtain the luminescent material. It seems, that simultaneous introduction of Ge is needed to provide the charge compensation for heterovalent Cu2+ → Al3+ substitution, in such a way that the whole process (Cu2+, Ge4+) → 2Al3+ is charge‐balanced. The broad photoluminescence spectrum matches well with transparency window of silica optical fibers and the quantum yield seems to be satisfactory, so copper‐doped corundum can become demanded as a new active media for solid state lasers and amplifiers. This is the first example of photoluminescence from octahedrally coordinated Cu2+ ion in oxide materials. [ABSTRACT FROM AUTHOR]

Single crystal of TlCl was doped with NIR photoluminescent univalent bismuth cations by prolonged immersion in liquid bismuth metal. The ion exchange Tl+ + Bi0 ↔ Tl0 + Bi+ at the crystal surface with subsequent Bi+ migration to the bulk are expected to drive the doping process. Contrary with Bi‐doped TlCl crystals, grown by Bridgman method, the ion exchange does not produce the additional nonluminescent bismuth‐containing centers. The investigation of photoluminescence emission and excitation spectra lead to the conclusion, that Bi+ is the main NIR emissive center in Bi‐doped TlCl. Near‐IR photoluminescent univalent bismuth cations can be introduced into TlCl crystal by ion exchange route. [ABSTRACT FROM AUTHOR]