Thermal and structural analysis of germanate glass and thin films co-doped with silver nanoparticles and rare earth ions with insights from visible and Raman spectroscopy

Abstract

This paper reports on the thermal and optical properties of germanate glasses GeO 2-PbO co-doped with silver nanoparticles and rare earth ions (Tm 3+ , Er 3+ and Yb 3+) with a focus on the thermal diffusivity (D). The presence of rare earth ions and nanoparticles is evidenced by absorption spectra and TEM images, respectively. Additionally, a structural comparison between thin films and bulk glass with the same nominal composition is given. It is found that D increases up to 20% in samples where nanoparticles are present, although their quantity corresponds only to a volume fraction of 1.7%. Therefore, such enhancement could be associated with the nanoparticles. Nevertheless, a Raman analysis revealed a structural change after the thermal treatment used for the nucleation of the nanoparticles. A decrease in the intensity of the band at 534 cm À1 in the Raman spectra is interpreted as the disruption of the 3-membered rings of the GeO 4 tetrahedra. The Raman analysis also revealed the formation of small crystals of a-GeO 2 type quartz and the adsorption of carbon dioxide on the surface of the silver nanoparticles inserted in the germanate thin film. 2016 Elsevier B.V. All rights reserved.

One‐pot green synthesis and structural characterisation of silver nanoparticles using aqueous leaves extract of Carissa carandas : antioxidant, anticancer and antibacterial activities

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