Molecular simulation for thermoelectric properties of c-axis oriented hexagonal GeSbTe model clusters

• Main Authors: Vora-ud A., Rittiruam M., Kumar M., Han J., Seetawan T.
• Format: Journal
• Published: 2017
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84947765594&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/42160
• Institution: Chiang Mai University

© 2015 Elsevier Ltd. Using a combination of molecular orbital and molecular dynamics simulations, electronic and thermoelectric properties of GeSbTe model clusters are presented. The unit cells of Ge 13 Sb 20 Te 52 , Ge 7 Sb 12 Te 40 and Ge 14 Sb 6 Te 26 model clusters are designed corresponding to GeSb 2 Te 4 , GeSb 4 Te 7 and Ge 2 Sb 2 Te 5 compositions in hexagonal phase, oriented in the c-axis direction. The electronic structures of clusters have been simulated by discrete-variational molecular orbital calculation using Hartree-Fock-Slater approximation to determine the electrical conductivity and Seebeck coefficients in Mott expression. For thermal properties, molecular dynamics simulations have been employed on clusters in amorphous, cubic and hexagonal phases using Verlet's algorithm and subsequently using Green-Kubo relation for lattice thermal conductivity. We assumed inter-atomic interaction, defined by the Morse-type potential function added to Busing-Ida potential function, which considers partial electronic charges on the ions, bond length of the cation-anion pair, and depth and shape of the potential. Based on our simulations, detailed variation of electrical conductivity, carrier thermal conductivity, lattice thermal conductivity, Seebeck coefficients, power factor and figure of merit, are presented as a function of temperature in 300-700 K range. Thermoelectric parameters obtained in present study were compared and explained with those of experimentally results of Ge 2 Sb 2 Te 5 composition in hexagonal phase.