Elastic stability and electronic structure of fcc Ti, Zr, and Hf: A first-principles study

Aguayo, A.; Murrieta, Gabriel; Coss, Romeo de

doi:10.1103/physrevb.65.092106

Cited by 120 publications

(52 citation statements)

References 23 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%

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%

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

Schönecker

Koepernik

et al. 2015

RSC Adv.

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“…It was suggested that the transformation occurred as a means to reduce the intrinsic stresses formed during alloy processing. Finally, FCC Ti has been theoretically shown to exist by Aguayo et al using first principles calculations [20] and by Xiong et al using a Gibb's free energy calculation [21]. Xiong et al's calculations showed that the FCC phase was thermodynamically stable in Ti nanoparticles with diameters below~27 nm at elevated temperatures (~882°C).…”

Section: Introductionmentioning

confidence: 99%

In situ TEM observation of FCC Ti formation at elevated temperatures

Kacher

Gammer

et al. 2017

Scripta Materialia

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Pure Ti traditionally exhibits the hexagonal closed packed (HCP) crystallographic structure under ambient conditions and the body centered cubic (BCC) structure at elevated temperatures. In addition to these typical structures for Ti alloys, the presence of a face centered cubic (FCC) phase associated with thin films, interfaces, or high levels of plastic deformation has occasionally been reported. Here we show that small FCC precipitates form in freestanding thin foils during in situ transmission electron microscope (TEM) heating and we discuss the potential origins of the FCC phase in light of the in situ observations. This FCC phase was found to be stable upon cooling and under ambient conditions, which allowed us to explore its mechanical properties and stability via nanomechanical in situ TEM testing. It was found that FCC platelets within the HCP matrix phase were stable under mechanical deformation and exhibited similar mechanical deformation behavior as the parent HCP phase.

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“…1(d) for shorter film deposition period. It may be mentioned that based on elastic stability criterion, the possibility of a locally stable fcc Ti phase was proposed earlier [11]. In the last section of the paper, stability of hcp Ti phase in polycrystalline Ti thin films has been considered from a thermodynamic point of view.…”

Section: Thickness Dependence: Polycrystalline Thin Filmsmentioning

confidence: 99%

“…both contraction and expansion of lattice) has been reported in ultra-thin nanocrystalline Ni thin films [10]. Such lattice contraction or lattice expansion arising due to certain stress fields (without going into the debate of the origin of stress existing in the literature) inside the grains leads to change of specific volume (volume/atom) of the lattice which may cause lattice instability due to the change in the total energy of the lattice structure [1,6,11]. Fig.…”

Section: Thickness Dependence: Polycrystalline Thin Filmsmentioning

confidence: 99%