Modification of the Phonon Spectrum and Transport Properties of Materials via Substitutional Doping Observed with the Brillouin-Mandelstam Spectroscopy

ORAL

Abstract

The ability to modify the propagation of acoustic phonons has important implications for thermal management of electronics. The thermal transport in nanostructured or doped materials can be affected via the changed phonon–boundary and phonon–point defect scattering rates. However, the thermal conductivity can also be altered via the changes in the phonon group velocity. In this presentation, we show on the example of neodymium (Nd) doped sapphire (Al2O3), that substitution of Al atoms with much heavier Nd atoms results in a noticeable decrease in the acoustic phonon group velocity. The acoustic phonon spectra for each sample were measured directly using the Brillouin-Mandelstam spectroscopy (BMS) at room temperature. Our BMS results clearly show that with the increase in the Nd doping, the frequency of both longitudinal acoustic and transverse acoustic phonon modes, at fixed phonon wave-vector, decreases, indicating the change in the phonon group velocities.

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Presenters

  • Fariborz Kargar

    Department of Electrical and Computer Engineering/Materials Science and Engineering Program, University of California, Riverside, Electrical and Computer Engineering, University of California, Riverside, Electrical and Computer Engineering, University of California Riverside

Authors

  • Fariborz Kargar

    Department of Electrical and Computer Engineering/Materials Science and Engineering Program, University of California, Riverside, Electrical and Computer Engineering, University of California, Riverside, Electrical and Computer Engineering, University of California Riverside

  • Elias Penilla

    Department of Mechanical and Aerospace Engineering, University of California, San Diego

  • Ece Aytan

    Electrical and computer Engineering, Univ of California - Riverside, Department of Electrical and Computer Engineering, University of California, Riverside, Electrical and Computer Engineering, University of California, Riverside, Material Science and Engineering, University of California Riverside

  • Jacob Lewis

    Department of Electrical and Computer Engineering/Materials Science and Engineering Program, University of California, Riverside, Electrical and Computer Engineering, University of California, Riverside

  • Ruben Salgado

    Electrical and Computer Engineering, University of California, Riverside

  • Javier Garay

    Mechanical & Aerospace Engineering, University of California, San Diego, Department of Mechanical and Aerospace Engineering, University of California, San Diego

  • Alexander Balandin

    Electrical and Computer Engineering , University of California, Electrical and Computer Engineering, University of California Riverside, Electrical and computer Engineering, Univ of California - Riverside, Department of Electrical and Computer Engineering/Materials Science and Engineering Program, University of California, Riverside, Department of Electrical and Computer Engineering, University of California, Riverside, Electrical and Computer Engineering, University of California, Riverside, University of California Riverside