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The roles of Mn 2+ ions in the MnCO 3 compound, leading to the formation of an Mn 2+ -Yb 3+ dimer and affecting the gain coefficient for the 4 I 13/2 → 4 I 15/2 transition of Er 3+ ions and near-infrared (NIR) emission bandwidth flatness of Er 3+ /Tm 3+ /Yb 3+ co-doped in SiO 2 -ZnO-BaO (SZB) barium zinc silicate glasses, were investigated in this work. The composition of all elements from the original raw materials that exist in the host glasses was determined using energy-dispersive X-ray spectroscopy (EDS). Under the excitation of a 980 nm laser diode (LD), the NIR emission of Er 3+ /Tm 3+ /Yb 3+ -co-doped SZB glasses produced a bandwidth of about 430 nm covering the O, E, and C bands. The effects of Mn 2+ ions and the Mn 2+ -Yb 3+ dimer on the gain coefficient for the 4 I 13/2 → 4 I 15/2 transition of Er 3+ ions and bandwidth flatness of NIR emission of Er 3+ /Tm 3+ -co-doped and Er 3+ /Tm 3+ /Yb 3+ -co-doped SZB glasses were also assigned. The optimal molar concentration of Mn 2+ ions was determined such that the NIR bandwidth flatness of Er 3+ /Tm 3+ /Yb 3+ -co-doped SZB glasses was the flattest. In addition, the role of Mn 2+ ions in reducing the gain coefficient for the 4 I 13/2 → 4 I 15/2 transition of Er 3+ ions was also calculated and discussed., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

In this study, the indirect/direct optical band gaps and spectroscopy properties of Bi m + /Eu n + /Yb 3+ co-doped ( m = 0, 2, 3; and n = 2, 3) zinc calcium silicate glasses under different excitation wavelengths were investigated. Zinc calcium silicate glasses with the main compositions of SiO 2 -ZnO-CaF 2 -LaF 3 -TiO 2 were prepared by the conventional melting method. EDS analysis was performed to determine the elemental composition existing in the zinc calcium silicate glasses. Visible (VIS)-, upconversion (UC)-, and near-infrared (NIR)-emission spectra of Bi m + /Eu n + /Yb 3+ co-doped glasses were also investigated. Indirect optical band gaps and direct optical band gaps of Bi m + -, Eu n + - single-doped, and Bi m + -Eu n + co-doped SiO 2 -ZnO-CaF 2 -LaF 3 -TiO 2 -Bi 2 O 3 -EuF 3 -YbF 3 zinc calcium silicate glasses were calculated and analyzed. CIE 1931( x , y ) color coordinates for VIS and UC emission spectra of Bi m + /Eu n + /Yb 3+ co-doped glasses were determined. Besides, the mechanism of VIS-, UC-, NIR-emissions, and energy transfer (ET) processes between Bi m + and Eu n + ions were also proposed and discussed., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, lanthanum aluminosilicate glasses with compositions of 45SiO 2 -20Al 2 O 3 -12.5LaF 3 -10BaF 2 -9K 2 O-1Cr 2 O 3 -2.5Yb 2 O 3 (SALBK) were prepared using the conventional melting method and copper-potassium ion exchange process. Influences of the ion exchange process between copper and potassium on the visible, upconversion, and near-infrared luminescence spectra of Cr 3+ /Yb 3+ co-doped under excitations of 343, 490, and 980 nm LD were investigated. The EDS analysis of SALBK glasses was measured to confirm the presence of atoms in the glasses. The values of direct and indirect bandgaps of Cr 3+ /Yb 3+ co-doped SALBK glasses were calculated and analyzed. Besides, the energy exchange processes between Cu + , Cu 2+ ions, and Cr 3+ , Yb 3+ ions were also proposed and discussed., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)