4'1 Introduction to CASTEP 1 - PowerPoint PPT Presentation

1 / 9
About This Presentation
Title:

4'1 Introduction to CASTEP 1

Description:

Typical applications involve studies of surface chemistry, structural properties, ... choose a better element as a B-site dopant in SrTiO3 to lower the oxygen ion ... – PowerPoint PPT presentation

Number of Views:747
Avg rating:3.0/5.0
Slides: 10
Provided by: zzm
Category:

less

Transcript and Presenter's Notes

Title: 4'1 Introduction to CASTEP 1


1
4.1 Introduction to CASTEP (1)
  • CASTEP is a state-of-the-art quantum
    mechanics-based program designed specifically for
    solid-state materials science. CASTEP employs the
    density functional theory plane-wave
    pseudo-potential method, which allows you to
    perform first-principles quantum mechanics
    calculations that explore the properties of
    crystals and surfaces in materials such as
    semiconductors, ceramics, metals, minerals, and
    zeolites.
  • Typical applications involve studies of surface
    chemistry, structural properties, band structure,
    density of states, and optical properties. CASTEP
    can also be used to study the spatial
    distribution of the charge density and wave
    functions of a system.

2
4.1 Introduction to CASTEP (2)
  • CASTEP can be used effectively to study
    properties of both point defects (vacancies,
    interstitials, and substitutional impurities) and
    extended defects (e.g., grain boundaries and
    dislocations) in semiconductors and other
    materials.
  • Furthermore, the vibrational properties of solids
    (phonon dispersion, total and projected density
    of phonon states, thermodynamic properties) can
    be calculated with CASTEP using either the linear
    response methodology or the finite displacements
    technique. The results can be used in various
    ways, for instance, to investigate the
    vibrational properties of adsorbates on surfaces,
    to interpret experimental neutron spectroscopy
    data or vibrational spectra, to study phase
    stability at high temperatures and pressures,
    etc. The linear response method can also be used
    to calculate the response of a material to an
    applied electric field - polarizability for
    molecules and dielectric permittivity in solids -
    and to predict IR spectra.

3
4.2 Modeling
  • Figure 4.1. Model for the motion energy
    calculation.
  • Supercell with an extra oxygen vacancy.
  • Supercell with a oxygen ion located at the saddle
    point.

4
4. 3 Choosing Parameters
  • The structural parameters were calculated by
    geometry optimization with high accuracy from
    first principles.
  • Calculations of the total energy of the systems
    were carried out using the pseudo-potential
    method.
  • All static calculations were performed using the
    CASTEP code with ultra soft pseudo-potentials and
    the Perdew-Burke-Ernzerhof (PBE) GGA exchange
    correlation term.
  • The ultra-find convergence of the total energy
    and the energy cutoff were chose.
  • Spin polarization was taken into account in this
    study.

5
4. 4 Examples
  • Example 1 migration energy of oxygen ion in the
    BaCo0.875B0.125O3(B Sc, Mn, Ni, Fe, Co, Y, Nb,
    In, Sn)

Figure 4.2 Migration energy of oxygen ion in the
BaCo0.875B0.125O3 system
6
4. 4 Examples
  • Example 2migration energy of oxygen ion in the
    Ba0.875A0.125CoO3(A La, Sr, Ba, Ca)

Figure 4.3 Migration energy of oxygen ion in the
Ba0.875A0.125CoO3 system
7
4. 4 Examples
  • Example 3 Calculation for oxygen ion migration
    in SrBO3
  • The aim of calculation was to choose a better
    element as a B-site dopant in SrTiO3 to lower the
    oxygen ion migration energy and thus increase the
    oxygen ion conductivity. The ion migration energy
    was referred to as the activation energy for
    oxygen ion conduction. The ion migration energies
    in SrBO3 (BSc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn,
    Ga, Ge, As, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Cd, In,
    Sn and Sb)

8
Figure 4.4 Migration energy of oxygen ion in the
SrBO3 system
X. Li et al. / Electrochemistry Communications 10
(2008) 15671570
9
4.5 Testing Methods
  • Electron-blocking method
  • Thermogravimetric testing
  • Concentration cell
  • Chemical titration
Write a Comment
User Comments (0)
About PowerShow.com