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Determination of growth regimes of Pd nanostructures on c-plane sapphire by the control of deposition amount at different annealing temperature

Abstract

Metallic nanoparticles (NPs) with the tunable physical, optical and catalytic properties lead to a wide range of applications including various optoelectronics, sensors and fuel cells. In this paper, we demonstrate the evolution of various physical properties, configurations, size and density of palladium (Pd) nanostructures on sapphire (Al2O3) (0001) by the systematic control of deposition amount (DA) at distinct annealing temperatures. The transformation of deposited thin films into the various Pd NPs is achieved by the dewetting of thin film by means of surface diffusion, nucleation, Volmer-Weber growth and surface energy minimization mechanism. Depending on the evolution of size, density and configuration, five distinctive regimes of Pd nanostructures are demonstrated: (i) nucleation and evolution of small NPs between 1 and 3 nm (ii) medium NPs with the dominating vertical growth between 5 and 20 nm, (iii) laterally expanded large NPs between 30 and 40 nm, (iv) irregular coalesced Pd NPs between 50 and 80 nm, and finally (v) voids evolution between 100 and 200 nm. Initial film thickness and annealing temperature play major roles on the dewetting process and the resulting Pd nanostructures are notably distinguished. The fabricated Pd nanostructures has the influence on the lattice vibration modes of sapphire (0001) such as gradual decrement in the intensity and left shift of peak position with the increased surface coverage. In addition, the optical properties are studied by UV-VIS-NIR (300 – 1100 nm) reflectance spectra, which shows the reflectance, absorption and scattering over the wavelength and are closely related to the morphology evolution of Pd nanostructures.

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Publication details

The article was received on 04 Mar 2017, accepted on 12 May 2017 and first published on 16 May 2017


Article type: Paper
DOI: 10.1039/C7CP01410D
Citation: Phys. Chem. Chem. Phys., 2017, Accepted Manuscript
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    Determination of growth regimes of Pd nanostructures on c-plane sapphire by the control of deposition amount at different annealing temperature

    S. Kunwar, M. Sui, P. Pandey, Q. Zhang, M. Li, H. Bhandari and J. Lee, Phys. Chem. Chem. Phys., 2017, Accepted Manuscript , DOI: 10.1039/C7CP01410D

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