The effect of Al 3+ions on the self-reduction process of Yb 3+to Yb 2+ions and optical properties of Nd 3+/Yb n + (n=3, 2) co-doped transparent silicate glass-ceramics containing Ba 2 LaF 7 nanocrystals and Ag nanoparticles

The effect of Al 3 + ions in the AlF 3 compound on the reduction process of Yb 3 + to Yb 2 + ions in SiO 2- - AlF 3 - BaF 2 - TiO 2 - LaF 3 (SABTL) transparent silicate glass -ceramics was investigated. The valence states of the elements in the raw materials mixture existing in the transparent silicate glass -ceramics were determined using X-ray photoelectron spectroscopy (XPS) spectrum analysis. The transparent silicate glass -ceramics SABTL containing Ba 2 LaF 7 nanocrystals and Silver (Ag) nanoparticles (AgNPs) were identified through X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) image. With the increase of Al 3 + ions molar concentration, the self -reduction process of Yb 3 + to Yb 2 + ions was enhanced and thus significantly affected the optical bandgaps and upconversion (UC)-, near -infrared (NIR)- emissions of Nd 3 + /Yb 3 + co -doped in SABTL containing Ba 2 LaF 7 nanocrystals and AgNPs under excitation of 980 nm laser diode (LD). The optimal molar concentration ratio between SiO 2 and AlF 3 compound was determined such that the NIR bandwidth flatness of Nd 3 + /Yb 3 + co -doped in SABTL containing Ba 2 LaF 7 nanocrystals in the wavelength range of 1000-1200 nm was the flattest. In addition, the CIE 1931 (x, y) color coordinates for UC- and visible (VIS)- emissions of Nd 3 + /Yb 3 + co -doped SABTL-0.5Nd2Yb-xAg (x = 0, 2, 3, 4, and 5) glass -ceramics samples are also calculated and determined the color region for light -emitting diode (LED) application.