Effect of alkaline earth metal ions R2+ (R = Mg, Ca, Sr, and Ba) on the properties of LiNbO3 glass ceramics

Abstract

As a functional crystal, LiNbO₃ plays a significant role in nonlinear optics, optical storage, illumination, and three-dimensional display. Recent investigations have suggested that the precipitation of LiNbO₃ in a nonequilibrium system shows unique crystallite geometry and orientation, leading to fascinating nonlinear optical properties. This work focuses on the effect of alkaline earth metal ions on the properties of Li₂O–Nb₂O₅–SiO₂ glass ceramics. The results demonstrate that within the Li₂O–Nb₂O₅–SiO₂ glass matrix, irregularly shaped crystals of approximately 5 µm in size precipitate through volume crystallization. Upon incorporation of Mg²⁺, the glass ceramic remains in volume crystallization while LiNbO₃ crystals grow to 10 µm and become spherical. In contrast, the compositions containing Ca²⁺, Sr²⁺, and Ba²⁺ change to surface crystallization, producing submicron or even nano-sized crystals. Besides, the nonlinear optical response can be improved after the hybridization of alkaline earth metal oxides. This research offers insights into the crystallization behavior of LiNbO₃ crystals from the nonequilibrium environment.