Theoretical study of the relative stability of structural phases in group-III nitrides at high pressures

Abstract

We present the results of a first-principles theoretical study of the relative stability of several structural phases of the group-III nitrides AlN, GaN, and InN that complements the picture of the behavior under pressure of these technologically important materials. Along with structures which have been previously considered in other theoretical studies of these materials ͑comprising those of the observed phases: wurtzite, zinc-blende, and rocksalt; and the d-␤-Sn, NiAs, and CsCl structures͒ we have also assessed the stability of several novel structures, viz., the cinnabar structure, the Cmcm structure, and the sc16 structure, which have been recently observed in high-pressure experiments on various related compounds ͑e.g., GaAs͒ and have also been reported to be either stable or close to stable in a certain range of pressures in other III-V and II-VI compounds on the basis of first-principles calculations. Our results indicate, however, that in AlN, GaN, and InN, the high-pressure rocksalt phase remains stable with respect to any other phase considered in this study up to the highest pressures investigated of ϳ200 GPa, which agrees with the available experimental data. We have further considered the effect of the semicore d orbitals of GaN and InN on the phase diagram of these compounds.

Ab-<i>initio</i> Calculations of the Physical Properties in Gallium Nitride at Equilibrium Phases: Rocksalt and Wurtzite

“…As shown in Table 3, while our obtained the phase transition pressure value, showing quantitative deviation from the experimental value of 52.2 ± 3.0 [27] and theoretical values of 44.80 [2], 45.00 [5] and 40.00 [43], is comparable to that of other DFT within GGA and LDA calculation founded as 32.40 [3], 31.00 [6], and 33.7 [33], respectively.…”

Novel Pressure-Induced Structural Transformations of Inorganic Nanowires

“…By synchrotron energy-dispersive X-ray diffraction, Xia et al reported the first observation of rocksalt phase at an onset pressure of 37 GPa (Xia et al, 1993). Additional later studies confirmed that GaN with different forms all underwent the wurtzite to rocksalt transformation on compression, however, with large discrepancies in transition pressures (e.g., 42-54 GPa for experimental results (Halsall et al, 2004;Perlin et al, 1992;Ueno et al, 1994) and 37-55 GPa for some theoretical studies (AbuJafar et al, 2000;Cai & Chen, 2007;Mujica et al, 2003;Munoz & Kunc, 1991;Pandey et al, 1996;Serrano et al, 2000)). GaN can also be synthesized in the nanocrystalline form, either as nanowires or as quantum dots (Jorgensen et al, 2003;Liu et al, 2003;Zhou et al, 2005).…”

Electronic and Lattice Properties of Layered Hexagonal Compounds Under Anisotropic Compression: A First-Principles Study

“…The transformation from wurtzite to hexagonal for II-VI and III-IV compounds has already been studied. [9][10][11][12][13][14][15][16] In the above studies, treated compression conditions are basically hydrostatic (isotropic) with the exception of c=a compression 10,14) mentioned later. The hexagonal phase is treated as an intermediate or metastable phase between a wurtzite !…”

“…10,11,14) As for wAlN and w-ZnO, they transform into hexagonal phases under hydrostatic compression. 11,12,14) The transformation of 17,18) and has been theoretically studied. 19,20) At first, we investigated w-BN as one of the candidates.…”

“…21,22) In contrast, the transition pressures of AlN and ZnO from wurtzite to hexagonal under c-axis compression are lower than those under hydrostatic compression. 11,12,14) …”