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RESEARCH PRODUCT
Direction-dependent elastic properties and phononic behavior of PMMA/BaTiO 3 nanocomposite thin films
Wolfgang TremelHannah HuesmannGeorge FytasA. GueddidaBahram Djafari-rouhaniElena Alonso-redondoE. H. El BoudoutiO. El Aboutisubject
NanocompositeMaterials scienceCondensed matter physicsWave propagationPhononbusiness.industrySuperlatticeGeneral Physics and Astronomy02 engineering and technology021001 nanoscience & nanotechnology01 natural sciencesBrillouin zoneCondensed Matter::Materials ScienceOpticsDispersion relation0103 physical sciencesPhysical and Theoretical ChemistryPhase velocity010306 general physics0210 nano-technologyAnisotropybusinessdescription
Determination of the anisotropic mechanical properties of nanostructured hybrid films is of great importance to improve fabrication and to enable reliable utility. Here, we employ spontaneous Brillouin light spectroscopy to record the phononic dispersion relation along the two symmetry directions in a supported PMMA (poly(methylmethacrylate))-BaTiO3 hybrid superlattice (SL) with a lattice constant of about 140 nm. Several dispersive elastic modes are resolved for in-plane wave propagation, whereas along the periodicity direction the SL opens a wide propagation stop band for hypersonic phonons and near UV photons both centered at about 280 nm. A thorough theoretical analysis based on the finite element method quantitatively captures the band diagrams along the two main symmetry directions, helps identify the large density mismatch effect on the unexpectedly low sound phase velocity, and reveals significant anisotropy of the SL elastic tensor. Phonon propagation is a sensitive index of the structure, density, and the mechanical moduli of nanocomposite films.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2017-05-28 | The Journal of Chemical Physics |