Sm2O3 effect on structural, optical and isothermal properties of borophosphate glasses for solid-state lighting applications

The effect of Sm 2 O 3 on the structural, thermal, and optical properties 55 P 2 O 5 − 15 B 2 O 3 − 10 Na 2 O − ( 20 − x ) Li 2 O − ( x ) Sm 2 O 3 (x = 0.0, 0.5, 1.0, and 1.5 mol%) of glass and glass-ceramics are investigated. Sm 2 O 3 enhanced the creation of bridging oxygens by converting the phosphate units from P 0 ⟶ P n where n = 1, 2, and 3, along with a non-linear trend in the oxygen packing density and molar volume. The band gap increases from 3.79 to 3.96 eV as Sm 2 O 3 increases in as-prepared glasses. The emission spectra are in the blue-pink region for glasses and shift towards the pure blue region in glass-ceramics, particularly due to the evolution of Na 2 B 6 O 10 phase. The decay lifetime of glasses is decreased from 4.72 to 1.01 ms with Sm 2 O 3 concentration. The CIE (x, y) coordinates of x=1.5 glass are (0.38, 0.24), which is a closer approximation to pure white light coordinates (0.33, 0.33) emission, while in glass-ceramics, CIE coordinates are (0.16, 0.07). The conversion of glass into glass-ceramics provides a better, variable, and sample-based approach to functionalizing these materials for solid-state lighting applications.