Gas-phase nanoparticle formation and transport during pulsed laser deposition of Y1Ba2Cu3O7−d

摘要: The gas-phase growth and transport of nanoparticles are characterized at the low background oxygen pressures used for pulsed laser deposition high-Tc Y1Ba2Cu3O7−d superconducting films. Onset times nanoparticle formation were determined by intensified charge-coupled device imaging optical spectroscopy laser-induced fluorescence from diatomic oxides Rayleigh scattering gas-suspended nanoparticles. Nanoparticles detected above 175 mTorr room temperature, with continuing during seconds within cloud stopped vapor near heater surface. Elevated temperatures create density gradients which result in reduced resistance to initial plume expansion. temperature gradient also moves away surface as they grow, effectively limiting time spatial confinement necessary continued or aggregation, inhibiting thermophoresis.