Permanent densification of amorphous zinc oxide under pressure: A first principles study


TAHAOĞLU D., DURANDURDU M.

JOURNAL OF NON-CRYSTALLINE SOLIDS, vol.481, pp.27-32, 2018 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 481
  • Publication Date: 2018
  • Doi Number: 10.1016/j.jnoncrysol.2017.10.016
  • Journal Name: JOURNAL OF NON-CRYSTALLINE SOLIDS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.27-32
  • Keywords: ZnO, Amorphous, Densification, Phase transformation, THIN-FILMS, ZNO, PHASE, CRYSTAL
  • Abdullah Gül University Affiliated: Yes

Abstract

Ab initio simulations within a generalized gradient approximation are carried out to investigate the densification mechanism of amorphous zinc oxide (a-ZnO) under hydrostatic pressure. In contrast to the crystalline ZnO, the densification of a-ZnO is found to proceed gradually and is associated with a structural modification from a low density amorphous state to a high density amorphous state. Accompanied by the phase transformation, the mean coordination number increases from similar to 4.0 to similar to 5.5. The high-density amorphous form of ZnO has a local structure, partially comparable with that of the rocksalt type ZnO crystal and presents a semiconducting behavior. The phase change is irreversible because upon pressure release, an amorphous model largely consisting of fivefold coordination is recovered. The decompressed model can be, therefore, classified as an intermediate phase between the wurtzite-like and the rocksalt-like amorphous configurations.