CsLa(SO4)2: A Lanthanum Sulfate Crystal for Nonlinear Optical Applications

Nonlinear optical materials with ultraviolet transparency are vital for technologies. A sulfate crystal, CsLa(SO4)2, was synthesized via hydrothermal methods, adopting a noncentrosymmetric structure (Pmn21) with asymmetric La[SO4]7 coordination. The material exhibits a second-harmonic generation efficiency of 0.6 times KH2PO4 (KDP), a birefringence of 0.026 at 546 nm, and a UV cutoff below 200 nm. Its wide bandgap (5.27 eV) aligns with requirements for UV/deep-UV applications. Theoretical analysis suggests that La-O and S-O bonding interactions enhance optical performance, providing insights for optimizing sulfate-based materials.