The Synthesis, Structure, and Luminescent Properties of TmMgB 5 O 10 Crystals.

TmMgB5 O10 spontaneous crystals were synthesized via the flux-growth technique from a K2 Mo3 O10 -based solvent. The crystal structure of the compound was solved and refined within the space group P 21 / n . The first principles calculations of the electronic structure reveal that TmMg-pentaborate with an ideal not defected crystal structure is an insulator with an indirect energy band gap of approximately 6.37 eV. Differential scanning calorimetry measurements and powder X-ray diffraction studies of heat-treated solids show that TmMgB5 O10 is an incongruent melting compound. A characteristic band of the Tm3+ cation corresponding to the 3 H6 → 1 D2 transition is observed in the photoluminescence excitation spectra of TmMg-borate. The as-obtained crystals exhibit intense blue emission with the emission peaks centered at 455, 479, 667, and 753 nm. The most intensive band corresponds to the 1 D2 → 3 F4 transition. TmMgB5 O10 solids demonstrate the thermal stability of photoluminescence.