Synthesis and morphology of Ba1−xRE2x/3Nb2O6 nanocrystals with tungsten bronze structure in RE2O3–BaO–Nb2O5–B2O3 glasses (RE: Sm, Eu, Gd, Dy, Er)

Ba1−xRE2x/3Nb2O6 nanocrystals with a tetragonal tungsten bronze (TTB) structure are synthesized using a conventional glass crystallization technique in 2.3RE2O3–27.4BaO–34.3Nb2O5–36B2O3 (mol%) (RE=Sm, Eu, Gd, Dy, and Er) glasses. One sharp crystallization peak is observed at ∼670 °C in both powdered and bulk glasses, and the formation of Ba1−xRE2x/3Nb2O6 nanocrystals with unit cell parameters of a∼1.24 nm and c∼0.39 nm was confirmed. It is found from high resolution transmission electron microscope observations that the morphology of Ba1−xRE2x/3Nb2O6 nanocrystals is ellipsoidal. Their average particle size is in the range of 15–60 nm and decreases with decreasing ionic radius of RE3+ being present in the precursor glasses. The optical transparent crystallized glass (bulk) shows the total photoluminescence (PL) quantum yield of 53% in the visible region of Eu3+ ions, suggesting a high potential of Ba1−xRE2x/3Nb2O6 nanocrystals as PL materials.