Investigation of surface charging characteristics of ion-irradiated alumina ceramics: Transition from secondary electron emission to charge injection. - Liu, Hao-Yan; An, Wen-Tong; Sun, Guang-Yu; Zhou, Sheng; Qi, Chang-Chun; Liu, Yue-Lin; Liu, Yan-Qi; Li, Wen-Rui; Zhang, Guan-Jun (Applied Physics Letters, 2025)