  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.
