Elucidating the effect of Pb and Ba substitution in SrTcO3 for advanced radioactive semiconducting applications

Abstract

In this work, lead (Pb) and barium (Ba) substitution in SrTcO3 (STO) has been studied in detail using density functional theory. The structural stability was tested using optimization, enthalpy of formation and tolerance factor. The structure of SrTc(1−x)ZxO3 for (Z = Ba and Pb; x = 0, 0.25, 0.50 and 0.75) is found to be thermodynamically stable and thus can be made and studied experimentally, in which 25% Ba is the most stable form with ΔH = − 25.43 eV. In electronic properties, the band analysis is performed using PBE-GGA functional and found to follow the Moss–Burstein shift for the studied compounds, while DOS and contour plots have shown mixed p–d hybridization among the constituent elements, which indicates a mixing of covalent and ionic bond between its content atoms. The magnetic properties revealed the existence of weak ferromagnetism which is found to decrease (6.45, 6.02, 6.00 μB) with the increase of Pb content in STO while it increases to (0.04, 5.24, 6.89 μB) for the Ba substitution. Ba substitution shows good electrical conductivity. The optical analysis has shown a high reflectivity value for visible light (especially for 50% Ba with R(0) = 91.3%) and high conductivity σ(ω) (especially for 50% Ba with 12.6 × 103/Ω cm) value in the UV region which suggests the ability of these materials to be used as optical reflectors to prevent radiations and as non-radioactive photocatalysis and optoelectronic sensors.