Terahertz acoustic phonon detection from a compact surface layer of spherical nanoparticles powder mixture of aluminum, alumina and multi-walled carbon nanotube

Abstract We present terahertz spectroscopy study on spherical nanoparticles powder mixture of aluminum, alumina, and MWCNTs induced by surface mechanical attrition treatment (SMAT) of aluminum substrates. Surface alloying of AL, Al 2 O 3 0.95% and MWCNTs 0.05% powder mixture was produced during SMAT process, where a compact surface layer of about 200 μ m due to ball bombardment was produced from the mixture. Al 2 O 3 alumina powder played a significant role in MWCNTs distribution on surface, those were held in deformation surface cites of micro-cavities due to SMAT process of Al. The benefits are the effects on resulted optical properties of the surface studied at the terahertz frequency range due to electrical isolation confinement effects and electronic resonance disturbances exerted on Al electronic resonance at the same range of frequencies. THz acoustic phonon around 0.53–0.6 THz (17–20 cm  −1 ) were observed at ambient conditions for the spherical nanoparticles powder mixture of Al, Al 2 O 3 and MWCNTs. These results suggested that the presence of Al 2 O 3 and MWCNTs during SMAT process leads to the optically detection of such acoustic phonon in the THz frequency range.