Theoretical Prediction‐Assisted Synthesis and Characterization of Infrared Nonlinear Optical Material NaSrBS₃

Abstract NaSrBS₃, the first noncentrosymmetric alkali and alkaline earth metal mixed thioborate with the isolated [BS₃] as the building units, has been synthesized successfully under the guidance of theoretical prediction. Comprehensive characterizations reveal that NaSrBS₃ exhibits wide bandgap (3.94 eV), large birefringence (0.185 at 1064 nm), a high laser‐induced damage threshold (9 × AGS), and a suitable phase‐matching second‐harmonic generation (SHG) response (0.3 × AGS). Structure‐properties analyses illustrate that the [BS₃] units determine the bandgap and contribute the most to the birefringence and SHG response. This work is the first successful case of “prediction to synthesis” involving infrared (IR) nonlinear optical (NLO) crystals in the thioborate system and provides an avenue to SHG materials design.