title: Ab initio investigation of CaO-ZnO alloys under high pressure.
abstract: Ca(x)Zn(1-x)O alloys are potential candidates to achieve wide band-gap, which might significantly promote the band gap engineering and heterojunction design. We performed a crystal structure search for CaO-ZnO system under pressure, using an ab initio evolutionary algorithm implemented in the USPEX code. Four stable ordered Ca(x)Zn(1-x)O structures are found in the pressure range of 8.7-60 GPa. We further constructed the pressure vs. composition phase diagram of CaO-ZnO alloys based on the detailed enthalpy calculations. With the increase in Ca concentration, the CaO-ZnO alloy first undergoes a hexagonal to monoclinic transition, and then transforms back to a hexagonal phase. At Above 9 GPa, there is no cubic structure in the alloys, in contrast to the insostructural components (B1-B1). The band gap of the Ca(x)Zn(1-x)O alloy shows an almost linear increase as a function of the Ca concentration. We also investigated the variation regularity of the band gap under pressure.
authors.affiliation: State Key Laboratory of Superhard Materials, College of physics, Jilin University, Changchun, 130012, P. R. China.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Sha
authors.affiliation: State Key Laboratory of Superhard Materials, College of physics, Jilin University, Changchun, 130012, P. R. China.
authors.forename: Fubo
authors.initials: F
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Superhard Materials, College of physics, Jilin University, Changchun, 130012, P. R. China.
authors.forename: Da
authors.initials: D
authors.lastname: Li
authors.affiliation: State Key Laboratory of Superhard Materials, College of physics, Jilin University, Changchun, 130012, P. R. China.
authors.forename: Defang
authors.initials: D
authors.lastname: Duan
authors.affiliation: State Key Laboratory of Superhard Materials, College of physics, Jilin University, Changchun, 130012, P. R. China.
authors.forename: Binhua
authors.initials: B
authors.lastname: Chu
authors.affiliation: State Key Laboratory of Superhard Materials, College of physics, Jilin University, Changchun, 130012, P. R. China.
authors.forename: Yunxian
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Superhard Materials, College of physics, Jilin University, Changchun, 130012, P. R. China.
authors.forename: Bingbing
authors.initials: B
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Superhard Materials, College of physics, Jilin University, Changchun, 130012, P. R. China.
authors.forename: Tian
authors.initials: T
authors.lastname: Cui