Physical Properties of APd3O4 (A=Ca, Sr, T1 and Cd) Type Palladates: An Ab-Initio Study

Abstract

Inthis thesis DFT andPost-DFT techniquesare usedto explore electronic, magnetic,mechanical,elastic,opticalandthermoelectricpropertiesofAPd3O4 (A = Ca, Sr, Cd and Tl) palladates. The electronic nature of these palladates are evaluated by using various theoretical models i.e LDA, GGA, GGA+U,TB-mBJandGGA+SOC.Thecalculatedelectronicbandstructure ofthesecompoundsCaPd3O4,SrPd3O4,CdPd3O4 andTlPd3O4 showthat CdPd3O4 ismetallicandCaPd3O4,SrPd3O4 andTlPd3O4 aresemiconductors. The band gaps of CaPd3O4, SrPd3O4 and TlPd3O4 are 0.12 eV , 0.10 eVand1.10eV ,respectively. Thecalculatedmechanicalpropertiesconfirm that these compounds are mechanically stable, elastically anisotropic and ductile in nature. The calculated optical properties reveal that CaPd3O4 and SrPd3O4 are active in the infrared region of the electromagnetic spectrum and TlPd3O4 is indirect band gap material and hence it is optically not active. Due to the small energy gaps and dense electronic states of these compounds around Fermi level, they seem to be good thermoelectric materials. Hence their thermoelectric properties are also evaluated by using the Boltzmann transport theory. The thermoelectric properties show that CaPd3O4 has the maximum value of the Seebeck coefficient in comparison with SrPd3O4 and TlPd3O4 for the given temperature range. The calculated results are found in close agreement with the available experimental results in literature. The density functional theory (DFT) and post-DFT calculations reveal the non-magnetic nature of these palladates.