From Polycrystalline Synthesis to Single‐Crystal Growth: Achieving High‐Optical‐Quality BaGa2GeSe6 crystal via a Dual‐Zone Approach. - Kong, Xiangran; Yan, Jingdong; Leng, Hongwei; Wang, Zichang; Liu, Tao; Hao, Sue; Lei, Zuotao; Yang, Chunhui (Crystal Research & Technology, 2026)