Rare earth pyrochlores crystals R2Ge2O7 (R=Er, Lu, Yb): Elastic and vibrational properties

In this work the ab initio investigation of the elastic and vibrational properties of rare-earth crystals R2Ge2O7 (R=Er, Yb, Lu) were carried out. The calculations were performed by using hybrid functional which takes into account both local and nonlocal -in the Hartree–Fock (HF) formalism-exchange...

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Bibliographic Details
Main Authors: Chernyshev, Vladimir A., Avram, Nicolae M.
Format: Conference Proceeding
Language:English
Subjects:
Brillouin zones
Bulk modulus
Crystals
Elastic properties
Erbium
Mathematical analysis
Modulus of elasticity
Periodic structures
Pyrochlores
Rare earth elements
Shear modulus
Ytterbium
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Summary:In this work the ab initio investigation of the elastic and vibrational properties of rare-earth crystals R2Ge2O7 (R=Er, Yb, Lu) were carried out. The calculations were performed by using hybrid functional which takes into account both local and nonlocal -in the Hartree–Fock (HF) formalism-exchange and the MO LCAO approach, with the CRYSTAL17 software designed to simulate periodic structures. The elastic constants, bulk, Young’s and shear modulus along the Young modulus of the direction of the crystals were calculated. The frequencies, type of vibrations at Г-point of first Brillouin zone and an analysis of the displacement vectors obtained from the ab initio calculation were obtained. These calculations allow to estimate the degree of the ion’s participation in the vibrational modes. The results of calculations are discussed and were compared with the existing measured data and the agreement is quite satisfactory. In the absence of measured data on the phonon spectra and the elastic constants, the theoretical results obtained by us represent predictions for future experimental investigations.
ISSN:0094-243X
1551-7616
DOI:10.1063/5.0001043