Epitaxial Bain paths and metastable phases from first-principles total-energy calculations

Marcus, P. M.; Jona, F.; Qiu, S. L.

doi:10.1103/physrevb.66.064111

Cited by 46 publications

(92 citation statements)

References 8 publications

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“…We find that the fcc structures of all investigated elements except Zn and bcc Zr are elastically stable, while most bct minima are unstable except those of the fourth group elements, bct Ti (c/a = 0.86), bct Zr (c/a = 0.82), and bct Hf (c/a = 0.85). The elastic stability of the fcc structures of Sc, Ti, Co, Y, Zr, Tc, Ru, Hf, Re, and Os [45,[48][49][50][51][52][53], the elastic stability of bct Zr [45] as well as the elastic instability of bct Co, fcc and bct Zn [24] was reported previously in accordance with the findings of the present work. There is, however, a discrepancy on the elastic stability of bcc Zr and bct Ti.…”

Section: A Elements With Stable Hcp Structuresupporting

confidence: 92%

“…The EBP is one possible realization of a Bain path, the principles of which were discussed by Alippi et al [23] and Marcus et al [24]. The EBP assumes those bct structures for which the lattice parameter c min is relaxed for every lattice parameter a.…”

Section: Methodsmentioning

confidence: 99%

“…Thus, provided that the two points of cubic symmetry belong to the EBP, E EBP (a) is not only extremal at these two points but there is at least one additional extremal point with noncubic (bct) symmetry [24,26]. In some cases, one of the cubic points does not belong to the EBP but E EBP (a) assumes a maximum close to this point [28].…”

Section: Methodsmentioning

confidence: 99%

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Metastable cubic and tetragonal phases of transition metals predicted by density-functional theory

Schönecker

Koepernik

et al. 2015

RSC Adv.

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By means of density-functional calculations, we systematically investigated 24 transition metals for possible metastable phases in body-centered tetragonal structure (bct), including face-centered cubic (fcc) and body-centered cubic (bcc) geometries. A total of 36 structures not coinciding with equilibrium phases were found to minimize the total energy for the bct degrees of freedom. Among these, the fcc structures of Sc, Ti, Co, Y, Zr, Tc, Ru, Hf, Re, and Os, and bct Zr with c/a = 0.82 were found to be metastable according to their computed phonon spectra. Eight of these predicted phases are not known from the respective pressure-temperature phase diagrams. Possible ways to stabilize the predicted metastable phases are illustrated.

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Section: A Elements With Stable Hcp Structuresupporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

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Metastable cubic and tetragonal phases of transition metals predicted by density-functional theory

Schönecker

Koepernik

et al. 2015

RSC Adv.

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“…49,50 A similar scheme is the Bain's path for the transition from the face-centered-cubic to the body-centered-cubic structure. 51 In the first step on the transition path (WZ ↔ HX), the internal parameter u is linearly increased while simultaneously decreasing the c /a ratio ( Fig. 1).…”

Section: Modeling the Structural Wz ↔ Rs Phase Transitionmentioning

confidence: 99%

Structural phase transitions and fundamental band gaps ofMgxZn1−xOalloys from first principles

et al. 2009

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The structural phase transitions and the fundamental band gaps of MgxZn1−xO alloys are investigated by detailed first-principles calculations in the entire range of Mg concentrations x, applying a multiple-scattering theoretical approach (Korringa-Kohn-Rostoker method). Disordered alloys are treated within the coherent potential approximation (CPA). The calculations for various crystal phases have given rise to a phase diagram in good agreement with experiments and other theoretical approaches. The phase transition from the wurtzite to the rock-salt structure is predicted at the Mg concentration of x = 0.33, which is close to the experimental value of 0.33 − 0.40. The size of the fundamental band gap, typically underestimated by the local density approximation, is considerably improved by the self-interaction correction. The increase of the gap upon alloying ZnO with Mg corroborates experimental trends. Our findings are relevant for applications in optical, electrical, and in particular in magnetoelectric devices.

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“…In all the cases, we find imaginary phonon frequencies that clearly indicate the dynamic instability of bulk Ru and Os, in the bct structure. It should be noted that the imaginary phonon branch in the Γ → X direction reveals an elastic instability related to a negative value of the elastic constant C ′ = (c 11 − c 12 )/2 [1,7,18]. Additionally, the effect of the epitaxial and uniaxial strains on the phonon dispersion was evaluated.…”

Section: Resultsmentioning

confidence: 99%

On the dynamical stability of ferromagnetic Ru and Os in the bct structure: a first-principles study

Cifuentes-Quintal

Coss

2015

Philosophical Magazine Letters

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Recent theoretical studies have predicted magnetic states for Ru and Os in the body centered tetragonal structure (bct) with c/a < 1. In this study, we present first principles calculations of the phonon dispersion for ferromagnetic Ru-and Os-bct along the epitaxial and uniaxial Bain paths, to evaluate their dynamical stability. The phonon dispersions were computed using the density functional perturbation theory, including the gradient corrections to the exchange-correlation functional within the plane-waves ultrasoftpseudopotential approximation. The phonon dispersion for the local minimum in the Bain path with c/a < 1 as well as the uniaxial and epitaxial strained structures are analyzed. We find imaginary frequencies along different directions of the Brillouin zone, which indicates that both systems are dynamically unstable. Consequently, ferromagnetic Ru and Os in the body centered tetragonal structure with c/a < 1 are not truly metastable phases.

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Epitaxial Bain paths and metastable phases from first-principles total-energy calculations

Cited by 46 publications

References 8 publications

Metastable cubic and tetragonal phases of transition metals predicted by density-functional theory

Metastable cubic and tetragonal phases of transition metals predicted by density-functional theory

Structural phase transitions and fundamental band gaps ofMgxZn1−xOalloys from first principles

On the dynamical stability of ferromagnetic Ru and Os in the bct structure: a first-principles study

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