Photoluminescence Study of Undoped and Eu-Doped Alkali-Niobate Aluminosilicate Glasses and Glass-Ceramics.

In this study, the photoluminescence (PL) behavior of two aluminosilicate glass series containing alkali-niobates ranging from 0.4 to 20 mol% was investigated. The glasses exhibit an intense visible emission centered at ~18,400 cm for the peralkaline series and at higher energies (~19,300 cm) for the metaluminous glasses.

Eu Site Distribution and Local Distortion of Photoluminescent Ca WO :(Eu , K ) Double Perovskites as High-Color-Purity Red Phosphors.

In this study, Eu and K co-doped Ca WO double perovskite, a high-color-purity red phosphor, is quantitatively investigated using synchrotron X-ray diffraction Rietveld refinement, energy dispersive X-ray spectroscopy, and high-resolution PL spectroscopy. The Eu fluorescence line-narrowing (FLN) results, used to estimate the Eu occupation at given sites (so-called A and B sites) in the host crystal (A BMO ; A, B = Ca; M = W), reveal that the Eu ions have a twin distribution in both the A and B sites with high asymmetry ratios of Λ  = 9.7 and Λ  = 10.

Thermal Evolutions to Glass-Ceramics Bearing Calcium Tungstate Crystals in Borate Glasses Doped with Photoluminescent Eu Ions.

Thermal evolutions of calcium-tungstate-borate glasses were investigated for the development of luminescent glass-ceramics by using Eu dopant in a borate glass matrix with calcium tungstate, which was expected to have a combined character of glass and ceramics. This study revealed that single-phase precipitation of CaWO crystals in borate glass matrix was possible by heat-treatment at a temperature higher than glass transition temperature for (100-) (33CaO-67BO)-CaWO ( = 8-15 mol%). Additionally, the crystallization of CaWO was found by Raman spectroscopy due to the formation of W=O double bondings of WO tetrahedra in the pristine glass despite starting with the higher calcium content of CaWO.