title: Pressure-induced structural and valence transition in AgO.
abstract: The pressure-induced evolution of AgO crystal structures and the oxygen environment of Ag atoms were investigated by means of density functional theory with a hybrid functional and a structure prediction method. Under ambient conditions, AgO has two nonequivalent Ag1 and Ag2 sites that adopt linear and square planar oxygen environment configuration, respectively, corresponding to Ag mixed-valence states. The results show that both the coordination environment and the valence state of the Ag1 site are sensitive to pressure and will gradually approach those of the Ag2 site as it increases. The band gap also decreases significantly and at 75 GPa AgO experiences a pressure-induced semiconductor-to-metal transition. At ∼77 GPa, there is a structural transition from monoclinic (P21/c) to trigonal (R3[combining macron]m), accompanied by a valence state transition from the mixed-valence state to a single-valence state.
authors.affiliation: School of Science, JiangXi University of Science and Technology, Ganzhou, 341000, P. R. China and Beijing Computational Science Research Center, Beijing 100094, P. R. China.
authors.forename: Chunju
authors.initials: C
authors.lastname: Hou
authors.affiliation: Beijing Computational Science Research Center, Beijing 100094, P. R. China and Department of Chemistry and Biochemistry California State University Northridge, CA 91330, USA. Jorge.botana@csun.edu jotabe1789@gmail.com.
authors.forename: Jorge
authors.initials: J
authors.lastname: Botana
authors.affiliation: School of Material Science and Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000, P. R. China.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Science, Hefei, 230031, P. R. China. xlwang@theory.issp.ac.cn.
authors.forename: Xianlong
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Chemistry and Biochemistry California State University Northridge, CA 91330, USA. Jorge.botana@csun.edu jotabe1789@gmail.com and Beijing Computational Science Research Center, Beijing 100094, P. R. China.
authors.forename: Maosheng
authors.initials: M
authors.lastname: Miao