# An ab-initio study on physical properties of Pd2+ incorporated double perovskites CaPd3B4O12 (B = Ti, V)

## TL;DR

This study uses density functional theory to explore the structural, electronic, optical, and thermoelectric properties of CaPd3B4O12 (B=Ti, V) double perovskites, revealing their stability, bonding nature, and potential for thermoelectric applications.

## Contribution

It provides a comprehensive ab-initio analysis of CaPd3B4O12 double perovskites, highlighting their stability, electronic behavior, and thermoelectric potential, which was not previously reported.

## Key findings

- Both compounds are mechanically stable and ductile.
- CPTO is a direct band gap semiconductor; CPVO is metallic.
- CPTO shows promising thermoelectric properties with ZT around 0.8 at 800 K.

## Abstract

Numerous physical properties of CaPd3Ti4O12 (CPTO) and CaPd3V4O12 (CPVO) double perovskites have been explored based on density functional theory (DFT). The calculated structural parameters fairly agree with the experimental data to confirm their stability. The mechanical stability of these two compounds was clearly observed by the Born stability criteria. To rationalize the mechanical behavior, we investigate elastic constants, bulk, shear and Young's modulus, Pugh's ratio, Poisson's ratio and elastic anisotropy index. The ductility index confirms that both materials are ductile in nature. The electronic band structure of CPTO and CPVO reveals the direct band gap semiconducting in nature and metallic characteristics, respectively. The calculated partial density of states indicates the strong hybridization between Pd 4d and O 2p orbital electrons for CPTO and Pd 4d and V 3d O 2p for CPVO. The study of electronic charge density map confirms the coexistence of covalent, ionic and metallic bonding for both compounds. Fermi surface calculation of CPVO ensures both electron and hole like surfaces indicating the multiple band nature. In the midst of optical properties, photoconductivity and absorption coefficient of both compounds reveal well qualitative compliance with consequences of band structure computations. Among the thermodynamic properties, the Debye temperature has been calculated to correlate its topical features including thermoelectric behavior. The studied thermoelectric transport properties of CPTO yielded the Seebeck coefficient (186 microVK-1), power factor (11.9 microWcm-1K-2) and figure of merit (ZT) value of about 0.8 at 800 K indicate that this material could be a promising candidate for thermoelectric device application.

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Source: https://tomesphere.com/paper/1904.05099