[Paper Review] A comparative theoretical study on physical properties of synthesized AVO3 (A = Ba, Sr, Ca, Pb) perovskites

Khandaker Monower Hossain, Mirza H. K. Rubel+6 more|arXiv (Cornell University)|May 4, 2019

Magnetic and transport properties of perovskites and related materials82 references21 citations

TL;DR

This theoretical study employs DFT-based CASTEP calculations to investigate the mechanical, electronic, optical, and thermal properties of ABO3 perovskites (A = Ba, Sr, Ca, Pb). It reveals that PbVO3 exhibits the highest Debye temperature and lowest thermal conductivity, indicating strong potential as a thermal barrier coating material, while all compounds show metallic behavior and dynamical stability only in BaVO3.

ABSTRACT

In this paper, we employ CASTEP based on DFT (density functional theory) calculations to investigate various physical properties of BaVO3, SrVO3, CaVO3 and PbVO3. The elastic constants, bulk modulus, Shear modulus, Young's modulus, Pugh's ratio, Poisson's ratio, Vickers hardness, universal anisotropy index and Peierls stress are calculated to rationalize the mechanical behavior of the aforementioned compounds. The study of electronic band structure and density of states (DOS) reveal the strong evidence of metallic behavior for all the perovskites. The analysis of bonding properties exhibits the existence of covalent, ionic and metallic bonds. The optical properties of AVO3 have been carried out and are discussed in this paper as well. The analysis of phonon property implies the dynamical stability of BaVO3 but not for SrVO3, CaVO3 and PbVO3. The values of Debye temperature and minimum thermal conductivity imply that only PbVO3 compound has potential to be used as TBC material.

Motivation & Objective

• To systematically compare the mechanical and physical properties of ABO3 perovskites (A = Ba, Sr, Ca, Pb) using first-principles calculations.
• To evaluate the mechanical stability and hardness of these perovskites through elastic constants and derived moduli.
• To analyze electronic structure and bonding character to understand metallic and covalent-ionic contributions.
• To assess optical and phononic properties for dynamical stability and thermal transport potential.
• To identify the most promising candidate for thermal barrier coating (TBC) applications based on thermal conductivity and Debye temperature.

Proposed method

• Density functional theory (DFT) with the CASTEP code was used to perform all electronic structure and property calculations.
• The generalized gradient approximation (GGA) with the PBE functional was employed for exchange-correlation interactions.
• Elastic constants were calculated using the stress-strain method under uniform strain deformation.
• Optical properties were evaluated from the dielectric function obtained via the independent-particle model.
• Phonon dispersion relations were computed to assess dynamical stability, with imaginary frequencies indicating instability.
• Thermal parameters such as Debye temperature and minimum thermal conductivity were derived from phonon spectra and elastic properties.

Experimental results

Research questions

• RQ1 Which ABO3 perovskite (A = Ba, Sr, Ca, Pb) exhibits the highest mechanical stability and hardness among the studied compounds?
• RQ2 What is the electronic nature (metallic or semiconducting) of BaVO3, SrVO3, CaVO3, and PbVO3 based on band structure and density of states?
• RQ3 Which compound shows the lowest thermal conductivity and highest Debye temperature, indicating suitability for thermal barrier coating applications?
• RQ4 To what extent do covalent, ionic, and metallic bonding contributions influence the physical behavior of these perovskites?
• RQ5 Which perovskite is dynamically stable based on phonon dispersion analysis?

Key findings

• All ABO3 perovskites (BaVO3, SrVO3, CaVO3, PbVO3) exhibit metallic behavior, as confirmed by their electronic band structures and density of states near the Fermi level.
• BaVO3 is dynamically stable, as indicated by the absence of imaginary phonon frequencies, while SrVO3, CaVO3, and PbVO3 show imaginary modes, indicating dynamical instability.
• PbVO3 has the highest Debye temperature (≈ 380 K) and the lowest minimum thermal conductivity (≈ 1.2 W/mK), making it the most promising candidate for thermal barrier coating applications.
• The universal anisotropy index and Vickers hardness values indicate that PbVO3 is the hardest among the studied compounds, with a hardness of approximately 12.5 GPa.
• Bonding analysis reveals significant covalent, ionic, and metallic contributions, with the metallic character dominating in all compounds due to the presence of V 3d electrons.
• Optical dielectric functions show strong absorption in the visible and near-UV range, indicating potential for optoelectronic applications.