Thermoelectric performance largely depends on the reduction of lattice thermal conductivity(kL).The study of the thermal conductivity(k)of a Sb_(2)Te_(3)/graphite nanocomposite system demonstrates-40%reduction in kL w...Thermoelectric performance largely depends on the reduction of lattice thermal conductivity(kL).The study of the thermal conductivity(k)of a Sb_(2)Te_(3)/graphite nanocomposite system demonstrates-40%reduction in kL with graphite incorporation.A plausible explanation of intrinsic low kL observed in Sb_(2)Te_(3) 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 Sb_(2)Te_(3)/graphite composite.Large reduction in kL 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 Sb_(2)Te_(3)/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.kL value as low as 0.8 W m1 K1 at 300 K,achieved with graphite dispersion in Sb_(2)Te_(3) based composite system makes the present comprehensive study an interesting concept to be developed in thermoelectric materials.展开更多
基金The authors gratefully acknowledge IUAC,New Delhi,India(Project reference no.:UFR-65307)and UGC DAE CSR,Kolkata,India(Project reference no.:UGC-DAE-CSR-KC/CRS/19/MS02/0939)for providing financial support for carrying out this worksupport during the experiments at the Indian Beamline,Photon Factory,KEK,Japan.Author P.Singha is thankful to UGC DAE CSR,Kolkata Centre,Govt.of India for providing him research fellowship.Author Subarna Das is grateful to UGC,Govt.of India for providing senior research fellowship and also acknowledges the support received through‘Raman-Charpak Fellowship 2019’jointly funded by the Department of Science and Technology(DST),Government of India and the French Institute in India(IFI),French Embassy in India,Ministry for Europe and Foreign Affairs,Government of France.
文摘Thermoelectric performance largely depends on the reduction of lattice thermal conductivity(kL).The study of the thermal conductivity(k)of a Sb_(2)Te_(3)/graphite nanocomposite system demonstrates-40%reduction in kL with graphite incorporation.A plausible explanation of intrinsic low kL observed in Sb_(2)Te_(3) 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 Sb_(2)Te_(3)/graphite composite.Large reduction in kL 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 Sb_(2)Te_(3)/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.kL value as low as 0.8 W m1 K1 at 300 K,achieved with graphite dispersion in Sb_(2)Te_(3) based composite system makes the present comprehensive study an interesting concept to be developed in thermoelectric materials.
