Strategically designed metal-free deep-ultraviolet birefringent crystals with superior optical properties

Four metal-free deep-ultraviolet birefringent crystals, exhibiting excellent optical properties were designed using Sr 2 Be 2 B 2 O 7 as template, and centimeter-sized C(NH 2 ) 3 CH 3 SO 3 crystals were successfully grown via a mild aqua-solution method.