Study of High-Temperature Behaviour of ZnO by Ab Initio Molecular Dynamics Simulations and X-ray Absorption Spectroscopy

Abstract

Wurtzite-type zinc oxide (w-ZnO) is a widely used material with a pronounced structural anisotropy along the c axis, which affects its lattice dynamics and represents a difficulty for its accurate description using classical models of interatomic interactions. In this study, ab initio molecular dynamics (AIMD) was employed to simulate a bulk w-ZnO phase in the NpT ensemble in the high-temperature range from 300 K to 1200 K. The results of the simulations were validated by comparison with the experimental Zn K-edge extended X-ray absorption fine structure (EXAFS) spectra and known diffraction data. AIMD NpT simulations reproduced well the thermal expansion of the lattice, and the pronounced anharmonicity of Zn–O bonding was observed above 600 K. The values of mean-square relative displacements and mean-square displacements for Zn–O and Zn–Zn atom pairs were obtained as a function of interatomic distance and temperature. They were used to calculate the characteristic Einstein temperatures. The temperature dependences of the O–Zn–O and Zn–O–Zn bond angle distributions were also determined.

In Situ Study of Zinc Peroxide Decomposition to Zinc Oxide by X‐Ray Absorption Spectroscopy and Reverse Monte Carlo Simulations

“…Finally, we compared in Figure 6 low (24 C) and high (900 C) temperature PDFs gðrÞ for Zn-O and Zn-Zn atom pairs in microcrystalline wurtzite-type ZnO [46] and the one produced from ZnO 2 . Their good agreement suggests that the crystallinity of nano-ZnO produced by decomposition almost recovers upon heating to 900 C. Nevertheless, some broadening of the outer shell peaks remains in both PDFs after cooling to 24 C.…”

In situ study of zinc peroxide decomposition to zinc oxide by X-ray absorption spectroscopy and reverse Monte-Carlo simulations

“…Finally, we compared in Figure 6 low (24 • C) and high (900 • C) temperature PDFs g(r) for Zn-O and Zn-Zn atom pairs in microcrystalline wurtzite-type ZnO [46] and the one produced from ZnO 2 . Their good agreement suggests that the crystallinity of nano-ZnO produced by decomposition almost recovers upon heating to 900 • C. Nevertheless, some broadening of the outer shell peaks remains in both PDFs after cooling to 24 • C.…”

Microwave-assisted synthesis and characterization of undoped and manganese doped zinc sulfide nanoparticles

“…where ϕ is a dimensionless correlation parameter [50]. For large interatomic distances (≥5-6 Å [50,51,52]), the correlation in the motion of atoms disappears, i.e. ϕ → 0, and MSRD is equal to the sum of two MSDs.…”