(Na0.60Ba0.70)Ga2Se4: An Infrared Nonlinear Optical Crystal Designed using AgGaSe2 as the Template

A novel quaternary selenide (Na 0.60 Ba 0.70 )Ga 2 Se 4 ( 1 ) obtained by a high-temperature method crystallizes in the non-centrosymmetric space group I 4 cm, and its structure features {[GaSe 2 ] − } ∞ chains. It exhibits phase-matchable second-harmonic generation responses with the largest intensity of 0.3 times that of AgGaS 2, and its powder sample has a laser-induced damage threshold of ∼2.4 times that of AgGaS 2 . Discussion about its relationship with other highly related structures are addressed as well. Theoretical calculations are performed to analyze its electronic structure and optical properties.