Sb2Te3/graphite nanocomposite: A comprehensive study of thermal conductivity

• Published in: Journal of Materiomics Vol. 7; no. 3; pp. 545 - 555
• Main Authors: Das, Subarna, Singha, P., Kulbachinskii, V.A., Kytin, V.G., Das, Gangadhar, Janaky, S., Deb, A.K., Mukherjee, Sudip, Maignan, A., Hebert, S., Daou, R., Narayana, Chandrabhas, Bandyopadhyay, S., Banerjee, Aritra
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2021; The Chinese Ceramic Society; Elsevier
• Subjects: Condensed Matter; Materials Science; Phonons; Physics; Raman spectroscopy; Specific heat measurements; Thermal conductivity; Thermoelectric systems; X-ray powder diffraction; Thermal conductivity; Specific heat measurements; Thermoelectric systems; Raman spectroscopy; Phonons; X-ray powder diffraction
• ISSN: 2352-8478
• DOI: 10.1016/j.jmat.2020.11.014

Thermoelectric performance largely depends on the reduction of lattice thermal conductivity (κL). The study of the thermal conductivity (κ) of a Sb2Te3/graphite nanocomposite system demonstrates ∼40% reduction in κL with graphite incorporation. A plausible explanation of intrinsic low κL observed in Sb2Te3 based system is presented by modeling experimental specific heat (Cp) data. Raman spectroscopy measurement combined to X-Ray diffraction data confirms the presence of graphite as separate phase in the composite sample. It is found that phonon scattering dominates heat transport mechanism in the nanostructured Sb2Te3/graphite composite. Large reduction in κL is accomplished by intensifying scattering rate of phonons via various sources. Graphite introduces effective scattering sources, i.e., defects of different dimensionalities in synthesized nanocomposite sample. Furthermore, graphite mediates phonon-phonon coupling and enhances lattice anharmonicity, which causes an intrinsic scattering of phonons with all frequencies in the Sb2Te3/graphite nanocomposite sample. Dislocation density and phonon anharmonicity of the synthesized samples are estimated from in depth analysis of temperature dependent synchrotron powder diffraction and Raman spectroscopic data. κL value as low as 0.8 W m−1K−1 at 300 K, achieved with graphite dispersion in Sb2Te3 based composite system makes the present comprehensive study an interesting concept to be developed in thermoelectric materials. [Display omitted] •40% reduction in lattice thermal conductivity is observed in Sb2Te3/graphite nanocomposite as compared to the pristine Sb2Te3.•A clue to intrinsic low lattice thermal conductivity of Sb2Te3 is obtained through experimental specific heat data.•Dislocation density in the samples is calculated using modified Williamson Hall method.•Anharmonic nature of phonons is demonstrated in the framework of symmetrical three phonon coupling model (Klemens’s model).•Thermal conductivity modelling is based on role of defects of different dimensionalities in phonon scattering.