Study on the effect of heat-annealing and irradiation on spectroscopic properties of Bi:α-BaB_2O_4 single crystal

Abstract

The absorption, excitation, and ultrabroadband near-infrared luminescence spectra of Bismuth were investigated in H(2)-annealed and gamma-irradiated Bi:alpha-BaB(2)O(4)(alpha-BBO) single crystals, respectively. Energy-level diagrams of the near-infrared luminescent centers were fixed. The electronic transition energies of near-infrared active centers are basically consistent with the multiplets of free Bi(+) ions. The minor difference of the energy-level diagrams of Bi(+) ions in H(2)-annealed and gamma-irradiated Bi:alpha-BaB(2)O(4) crystals can be ascribed to the difference of the local lattice environments. The involved physical and chemical processes were discussed. The effect of Ar-, air-annealing and electron-irradiation on Bi:alpha-BaB(2)O(4) crystal were also investigated.

Discussion on the origin of NIR emission from Bi-doped materials

“…electron energy loss spectroscopy (EELS), EXAFS or XPS, it remains unclear how much experimental artefacts have to be taken into account. That is, it is well-known that irradiation with high energy beams such as electrons, γ-ray, X-ray, or fs laser can modify the material's microstructure or induce photo-reduction or -oxidation [17,35,56,58]. This may partly put into question some of the reported data.…”

Surface-luminescence from thermally reduced bismuth-doped sodium aluminosilicate glasses

“…However, heattreatment of a bismuth-doped glass fiber in H 2 atmosphere with subsequent flame brushing negatively affected the NIR luminescence [29]. On the other hand, thermal reduction of bismuth-doped crystalline phosphors has been applied to increase NIR activity [34]. Heat-treatment of bismuth-doped glasses in a reducing atmosphere is thus a potential approach for manipulating the bismuth oxidation state and consequently the NIR luminescence.…”

Multifunctional tunable ultra-broadband visible and near-infrared luminescence from bismuth-doped germanate glasses

“…Furthermore, the direct measurements of the valence state of bismuth ions with traditional instrumental approaches, e.g., electron energy loss spectroscopy (EELS), extended x-ray absorption fine structure (EXAFS) or X-ray photoelectron spectroscopy (XPS), may cause some artifacts since the valence state of bismuth species can be changed when irradiated with high energy beams such as electrons, X-ray, c-ray, or fs laser. [20][21][22][23][24][25] 39 Single bismuth center with four different types is proposed for NIR luminescence in Bi-doped aluminosilicate optical fibers. 54 Bi þ and Bi 0 together were ascibed to contribute to the NIR luminescence.…”