Mesoporous silicon (pSi) has several interesting features that makes it suitable for various biomedical applications. In particular, the large surface area make it very sensitive to environment changes. Among other approaches, thermal oxidation is an effective way to passivate its surface. Herein, we present experimental and analytical results concerning kinetics of thermal oxidation reaction of pSi. The experiments were conducted on pSi powders produced from silicon wafer by anodization and converted to particles by sonication. Oxidation experiments were carried out at different heating rates. Structure and morphology of the samples have been investigated by XRD and SEM before and after thermal oxidation. The model-free kinetics proposed by Ozawa–Flynn–Wall (OFW) was used to determine the Arrhenius relationship for the pSi thermal oxidation. The obtained apparent activation energy by OFW was confirmed by Starink method. At low temperature, the oxidation of surface dangling bonds obeys the Avrami–Erofeev mechanism. At high temperature, oxidation is followed by classical bulk oxidation according to diffusion mechanism controlled by the diffusion of oxygen through the silicon dioxide layer on the surface of the pSi. The reaction mechanism was checked by the model fitting kinetics, which confirmed the reaction is a kind of sequential two-stage process, Avrami–Erofeev and 3D diffusion. Finally, differential thermal analysis suggests that the second oxidation step is also possibly affected by phase transformation of the silicon dioxide.
Scheda prodotto non validato
I dati visualizzati non sono stati ancora sottoposti a validazione formale da parte dello Staff di IRIS, ma sono stati ugualmente trasmessi al Sito Docente Cineca (Loginmiur).
|Titolo:||Isoconversional kinetics of thermal oxidation of mesoporous silicon|
|Autori:||Ghafarinazari, Ali; Zera, Emanuele; Lion, Anna; Scarpa, Marina; Sorarù, Gian Domenico; Mariotto, Gino; Daldosso, Nicola|
|Titolo del periodico:||THERMOCHIMICA ACTA|
|Anno di pubblicazione:||2016|
|Codice identificativo Scopus:||2-s2.0-84949215631|
|Codice identificativo WOS:||WOS:000369214800010|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1016/j.tca.2015.11.017|
|Appare nelle tipologie:||03.1 Articolo su rivista (Journal article)|
File in questo prodotto:
|thermochimica acta am 2015.pdf||Post-print referato (Refereed author’s manuscript)||Tutti i diritti riservati (All rights reserved)||Administrator|