An Ab Initio Study of Pressure-Induced Reversal of Elastically Stiff and Soft Directions in YN and ScN and Its Effect in Nanocomposites Containing These Nitrides

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dc.contributor.authorFriák, Martincs
dc.contributor.authorKroupa, Pavelcs
dc.contributor.authorHolec, Davidcs
dc.contributor.authorŠob, Mojmírcs
dc.coverage.issue12cs
dc.coverage.volume8cs
dc.date.accessioned2020-08-04T11:04:32Z
dc.date.available2020-08-04T11:04:32Z
dc.date.issued2018-12-01cs
dc.description.abstractUsing quantum-mechanical calculations of second- and third-order elastic constants for YN and ScN with the rock-salt (B1) structure, we predict that these materials change the fundamental type of their elastic anisotropy by rather moderate hydrostatic pressures of a few GPa. In particular, YN with its zero-pressure elastic anisotropy characterized by the Zener anisotropy ratio A Z = 2 C 44 / ( C 11 C 12 ) = 1.046 becomes elastically isotropic at the hydrostatic pressure of 1.2 GPa. The lowest values of the Young’s modulus (so-called soft directions) change from h 100 i (in the zero-pressure state) to the h 111 i directions (for pressures above 1.2 GPa). It means that the crystallographic orientations of stiffest (also called hard) elastic response and those of the softest one are reversed when comparing the zero-pressure state with that for pressures above the critical level. Qualitatively, the same type of reversal is predicted for ScN with the zero-pressure value of the Zener anisotropy factor A Z = 1.117 and the critical pressure of about 6.5 GPa. Our predictions are based on both second-order and third-order elastic constants determined for the zero-pressure state but the anisotropy change is then verified by explicit calculations of the second-order elastic constants for compressed states. Both materials are semiconductors in the whole range of studied pressures. Our phonon calculations further reveal that the change in the type of the elastic anisotropy has only a minor impact on the vibrational properties. Our simulations of biaxially strained states of YN demonstrate that a similar change in the elastic anisotropy can be achieved also under stress conditions appearing, for example, in coherently co-existing nanocomposites such as superlattices. Finally, after selecting ScN and PdN (both in B1 rock-salt structure) as a pair of suitable candidate materials for such a superlattice (due to the similarity of their lattice parameters), our calculations of such a coherent nanocomposite results again in a reversed elastic anisotropy (compared with the zero-pressure state of ScN).en
dc.formattextcs
dc.format.extent1-14cs
dc.format.mimetypeapplication/pdfcs
dc.identifier.citationNanomaterials. 2018, vol. 8, issue 12, p. 1-14.en
dc.identifier.doi10.3390/nano8121049cs
dc.identifier.issn2079-4991cs
dc.identifier.other155623cs
dc.identifier.urihttp://hdl.handle.net/11012/189001
dc.language.isoencs
dc.publisherMDPIcs
dc.relation.ispartofNanomaterialscs
dc.relation.urihttps://www.mdpi.com/2079-4991/8/12/1049cs
dc.rightsCreative Commons Attribution 4.0 Internationalcs
dc.rights.accessopenAccesscs
dc.rights.sherpahttp://www.sherpa.ac.uk/romeo/issn/2079-4991/cs
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/cs
dc.subjectYNen
dc.subjectScNen
dc.subjectpressureen
dc.subjectelasticityen
dc.subjectab initioen
dc.subjectstabilityen
dc.subjectnanocompositesen
dc.titleAn Ab Initio Study of Pressure-Induced Reversal of Elastically Stiff and Soft Directions in YN and ScN and Its Effect in Nanocomposites Containing These Nitridesen
dc.type.driverarticleen
dc.type.statusPeer-revieweden
dc.type.versionpublishedVersionen
sync.item.dbidVAV-155623en
sync.item.dbtypeVAVen
sync.item.insts2020.08.04 13:04:32en
sync.item.modts2020.08.04 12:43:27en
thesis.grantorVysoké učení technické v Brně. Středoevropský technologický institut VUT. Pokročilé kovové materiály a kompozity na bázi kovůcs
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Pokročilé kovové materiály a kompozity na bázi kovů