Lithium concentration effect on crystallization kinetics and spectral properties of Cr-doped Li2O-K2O-Al2O3-B2O3 glass-ceramics

Alkali-aluminaborate glass-ceramics doped with Cr ions are synthesized by volume crystallization. According to non-isothermal DSC method three parallel processes occur in material: 2D Avrami-Yerofeev nucleation, 2D and 3D crystallization. During the heat treatment, the LiAl7B4O17 crystalline phase is formed. With Li2O content rising crystallinity of the material increases from 27 to 69% and the crystalline field strength Dq/B of Cr3+ increases from 2.25 to 3.55. The photoluminescence spectra possess intense bands at 685, 700, and 715 nm for glass with 6.8 mol.% Li2O and higher and its decay kinetics is described by the sum of two exponentials. The maximum luminescence QY obtained is 50% at 16.1 mol.% Li2O. The highest conversion efficiency of the 532 nm LED luminescence obtained by glass-ceramics with chromium is 10%. Thus, Cr-doped alkali-alumina-borate glass-ceramics are a promising material for use in the design of radiation sources for the red and NIR spectral regions.