# Examples of SQS (special quasirandom structure) models for arbitrary binary bcc (body centered cubic) and hcp (hexagonal close packed) structures

https://mdr.nims.go.jp/datasets/61ee2fd8-0940-4b30-bba4-3d9962959f98

## File

- [atomic_coordinates_cif.zip](https://mdr.nims.go.jp/filesets/f221196f-45c9-48aa-8f5d-cf46f0dccc30/download) ([Detail](https://mdr.nims.go.jp/filesets/f221196f-45c9-48aa-8f5d-cf46f0dccc30.md))

## Id

61ee2fd8-0940-4b30-bba4-3d9962959f98

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2021-08-19T06:10:54.247358Z

## Updated at

2024-01-05T13:12:16.235682Z

## Published at

2021-08-19T13:30:05.937072Z

## Doi

https://doi.org/10.34968/nims.1429

## First published url

https://doi.org/10.1016/j.calphad.2020.102207

## Date published

2020-10-15

## Recorded date published

2020-12

## Resource type

dataset

## Manuscript type

authors_original

## Collection



## Title

- title: Examples of SQS (special quasirandom structure) models for arbitrary binary
    bcc (body centered cubic) and hcp (hexagonal close packed) structures
  title_type: original
  lang: en

## Description

- description: "These atomic coordinates are examples of SQS (special quasirandom
    structure) models for arbitrary binary bcc (body centered cubic) and hcp (hexagonal
    close packed) structures. These are constructed by 4x4x4 conventional cells (128
    atoms). \r\n\r\nRequest:\r\nWhen you publish results obtained using the atomic
    coordinates, kindly cite the publication:\r\n\r\nWenchong Zhou, Maaouia Souissi,
    Taichi Abe, Ryoji Sahara, Patrick H. -L. Sit, and Koichi Tsuchiya,\r\n\"Evaluating
    the phase stability of binary titanium alloy Ti-X (X = Mo, Nb, Al, and Zr) using
    first-principles calculations and a Debye model\"\r\nCALPHAD 71 (2020) 102207.
    \r\n\r\nand possibly the URL and/or DOI:\r\nhttps://mdr.nims.go.jp/concern/datasets/rv042v066?locale=en\r\n\r\nhttps://doi.org/10.34968/nims.1429\r\n\r\nABSTRACT:
    \r\nTo realize bottom-up design of alloys based on theoretical calculations, the
    thermodynamic stabilities of phases in Ti binary alloys were estimated by a combination
    of density functional theory calculations for the internal enthalpy energy, the
    Bragg-Williams approximation for the mixing entropy contribution, the Debye model
    for the vibrational free energy, and the Sommerfeld model for the electronic excitation
    entropy.\r\nThe special quasirandom structure model was used to describe the disordered
    distribution of the alloying element in the solid solution state. We focused on
    Ti-Mo, Ti-Nb, Ti-Al, and Ti-Zr binary alloys, which have different phases, such
    as the ¥alpha phase in the hexagonal close-packed (hcp) structure and the ¥beta
    phase in the body-centered cubic (bcc) structure,\r\ndepending on the temperature
    and alloying element fraction. The elastic constants, bulk modulus, and Poisson’s
    ratios were calculated using a strain energy method. Excitations from the vibrational
    contribution to the quasi-harmonic Debye approximation were added to the 0 K free
    energy originally derived from ab initio calculations. The effect of temperature
    up to 1000 K on phase stability was analyzed. Furthermore, to compare phase stabilities,
    the free energies of formation were calculated using the ground states of the\r\nconstituent
    phases as references. The calculated elastic property indicated the mechanical
    instability of most bcc Ti-Al and bcc Ti-Zr alloys, hcp Ti-Mo and hcp Ti-Nb at
    high fraction range. The special quasirandom structures (SQS) supercell models
    showed good agreement in elastic constant, bulk modulus, and Poisson’s ratio compared
    to the previous experimental and theoretical results. Free energy results showed
    that Mo and Nb are ¥beta-phase stabilizers, Al is an ¥alpha-phase stabilizer,
    and Zr is a neutral element. As the fraction of the alloying element changed,
    stabilizing or destabilizing effects were observed under different temperatures.
    Moreover, the linear relationship between the filling of the d band and phase
    stability was identified in low temperature range. For the ¥beta phase, Mo had
    a stronger stabilizing effect than Nb; both Mo and Nb destabilized the ¥alpha
    phase at low temperatures, whereas high temperatures increased the stability of
    the ¥alpha phase and the temperature effect became more significant than the element
    effect. In the examined temperature range, the ¥alpha phase Ti-Al alloys were
    stable at all Al fractions, where the thermal effect was negligible. All the ¥alpha
    Ti-Zr alloys in this study had similar stabilities to their constituent phases
    (hcp Ti and hcp Zr) over a wide temperature range.\r\n"
  description_type: abstract
  lang: en

## Creator

- name: SAHARA, Ryoji
  role: author
  orcid: https://orcid.org/0000-0003-0788-2985

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## Keyword

- subject: Sommerfeld model
  schema: not_defined
- subject: quasi-harmonic vibrational contribution
  schema: not_defined
- subject: First-principles calculation
  schema: not_defined
- subject: Debye model
  schema: not_defined
- subject: titanium alloys
  schema: not_defined

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- description: other

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## Fileset

- id: f221196f-45c9-48aa-8f5d-cf46f0dccc30
  filename: atomic_coordinates_cif.zip
  content_type: application/zip
  size: 28957
  md5: f66c5c424ab7c4ab3d2bcbdff1f52c25

## Thumbnail

fileset_id: f221196f-45c9-48aa-8f5d-cf46f0dccc30
filename: atomic_coordinates_cif.zip