Hartree-Fock study of phase changes in ZnO at high pressure

Jaffe, John E.; Hess, Aaron

doi:10.1103/physrevb.48.7903

Cited by 377 publications

(176 citation statements)

References 17 publications

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“…The transformation pressure observed here is consistent with experimental measurements in the range of 8.7-9.1 GPa (Desgreniers, 1998;Karzel et al, 1996). These values are higher than the phase equilibrium stress predicted by first-principles calculations (6.6-8.5 GPa) (Jaffe and Hess, 1993;Jaffe et al, 2000;Limpijumnong and Jungthawan, 2004). The difference is that, while the MD and experimental values are actual transformation stresses which reflect the effect of the energy barrier between the WZ and RS phases, the DFT phase equilibrium stress only indicates the level of stress at which the two phases are equally favored but does not relate to the stress required to overcome the energy barrier and activate the transformation.…”

Section: Uniaxial Tension Along the ½01 10 Orientationsupporting

confidence: 90%

Effect of load triaxiality on polymorphic transitions in zinc oxide

Kulkarni

Sarasamak

Wang

et al. 2008

Mechanics Research Communications

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Molecular dynamics (MD) simulations and first-principles calculations are carried out to analyze the stability of both newly discovered and previously known phases of ZnO under loading of various triaxialities. The analysis focuses on a graphite-like phase (HX) and a body-centered-tetragonal phase (BCT-4) that were observed recently in ½0 1 1 0 -and [0 0 0 1]-oriented nanowires respectively under uniaxial tensile loading as well as the natural state of wurtzite (WZ) and the rocksalt (RS) phase which exists under hydrostatic pressure loading. Equilibrium critical stresses for the transformations are obtained. The WZ ! HX transformation is found to be energetically favorable above a critical tensile stress of 10 GPa in ½01 10 nanowires. The BCT-4 phase can be stabilized at tensile stresses above 7 GPa in [0 0 0 1] nanowires. The RS phase is stable at hydrostatic pressures above 8.2 GPa. The identification and characterization of these phase transformations reveal a more extensive polymorphism of ZnO than previously known. A crystalline structure-load triaxiality map is developed to summarize the new understanding.

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Section: Uniaxial Tension Along the ½01 10 Orientationsupporting

confidence: 90%

Effect of load triaxiality on polymorphic transitions in zinc oxide

Kulkarni

Sarasamak

Wang

et al. 2008

Mechanics Research Communications

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“…In this work, we have selected the same basis sets for Zn and O that Jaffe and Hess used in their HF calculations of ZnO polymorphs. 14 This fact allows a direct comparison of their results with the local and nonlocal computations performed here. …”

Section: B Total Energy Calculationsmentioning

confidence: 79%

Compressibility of the high-pressure rocksalt phase of ZnO

et al. 1998

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We report the results of a combined experimental and theoretical investigation on the stability and the volume behavior under hydrostatic pressure of the rocksalt (B1) phase of ZnO. Synchrotron-radiation x-ray powder-diffraction data are obtained from 0 to 30 GPa. Static simulations of the ZnO B1 phase are performed using the ab initio perturbed ion method and the local and nonlocal approximations to the density-functional theory. After the pressure induced transition from the wurtzite phase, we have found that a large fraction of the B1 high-pressure phase is retained when pressure is released. The metastability of this ZnO polymorph is confirmed through the theoretical evaluation of the Hessian eigenvalues of a nine-parameter potential energy surface. This allows us to treat the experimental and theoretical pressure-volume data on an equal basis. In both cases, we have obtained values of the bulk modulus in the range of 160-194 GPa. For its zero-pressure first derivative, the experimental and theoretical data yield a value of 4.4Ϯ1.0. Overall, our results show that the ZnO B1 phase is slightly more compressible than previously reported. ͓S0163-1829͑98͒07537-7͔

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“…All-electron Gaussian orbital basis sets were used for Zn, 43 O, 44 Co, 45 and N. 46 For vacancy defects, a basis set corresponding to the ion removed was included at the site of the vacancy ion in order to allow a proper description of electrons localized in the vacancy. The local crystal structure around defects was relaxed, and details of their structures are given in the Appendix.…”

Section: Details Of Calculationsmentioning

confidence: 99%