Influence of Ternary and Quaternary Inclusion on Bandgap Tuning of CaTe: Prediction of Potential Thermoelectric Materials

• Published in: Journal of electronic materials 2021-04, Vol.50 (4), p.1759-1771
• Main Authors: Manjula, M., Muthumari, M., Krishnaveni, S., Kuznetsov, Denis, Veluswamy, Pandiyarasan
• Format: Article
• Language: English
• Subjects: Alloys; Asian Consortium ACCMS–International Conference ICMG 2020; Asian Consortium AC–CMS International Conference ICMG 2020; Brittleness; Bulk modulus; Characterization and Evaluation of Materials; Chemistry and Materials Science; Conduction bands; Density functional theory; Ductile-brittle transition; Electron density; Electronics and Microelectronics; Energy; Energy gap; II-VI semiconductors; Information technology; Instrumentation; Investigations; Materials Science; Mathematical analysis; Modulus of elasticity; Optical and Electronic Materials; Optical properties; Optoelectronics; Phase transitions; Plane waves; Seebeck effect; Shear modulus; Solid State Physics; Thermoelectric materials; Valence band
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-020-08485-0

The structural, optoelectronic, and thermoelectric properties of CaTe, Ca 0.5 Ba 0.5 Te, CaTe 0.5 Se 0.5 , and Ca 0.5 Ba 0.5 Te 0.5 Se 0.5 alloys are studied using the full-potential linearized augmented plane wave method within the framework of density functional theory. The calculated ground-state properties agree well with available data. The electronic and bonding behavior of the materials is studied and further verified by electron density contours. Additionally, mechanical stability is confirmed by calculating the shear modulus, Young’s modulus, bulk modulus, and hardness values. From the brittle/ductile analysis, the newly predicted compounds are found to be less brittle (more ductile) than the parent CaTe compound. The valence band maxima and the conduction band minima (CBM) of the Ca 0.5 Ba 0.5 Te, CaTe 0.5 Se 0.5 , and Ca 0.5 Ba 0.5 Te 0.5 Se 0.5 alloys are located at the Г point, resulting in a direct bandgap. The optical properties of the materials are calculated for the energy range of 0–13.5 eV. As expected, the highest Seebeck coefficient value is observed as 245.8 μV/K and 248.6 μV/K for CaTe 0.5 Se 0.5 and Ca 0.5 Ba 0.5 Te 0.5 Se 0.5 alloys, respectively, at 300 K. The present work exhibits the optoelectronic and thermoelectric properties, but the available material flexibility has various other applications.