Impact of γ-rays Irradiation on Hybrid TiO2-SiO2 Sol-Gel Films Doped with RHODAMINE 6G.

Maxime Royon,Yves Jourlin,Francis Vocanson,Aziz Boukenter,Damien Jamon,Cosimo Campanella,Youcef Ouerdane,Adriana Morana,François Royer,Sylvain Girard,Emmanuel Marin

doi:10.3390/ma14195754

Abstract

In the present paper, we investigate how the optical and structural properties, in particular the observed photoluminescence (PL) of photocurable and organic-inorganic TiO2-SiO2 sol-gel films doped with Rhodamine 6G (R6G) are affected by γ-rays. For this, four luminescent films, firstly polymerized with UV photons (365 nm), were submitted to different accumulated doses of 50 kGy, 200 kGy, 500 kGy and 1 MGy while one sample was kept as a reference and unirradiated. The PL, recorded under excitations at 365 nm, 442 nm and 488 nm clearly evidences that a strong signal peaking at 564 nm is still largely present in the γ-irradiated samples. In addition, M-lines and Fourier-transform infrared (FTIR) spectroscopies are used to quantify the radiation induced refractive index variation and the chemical changes, respectively. Results show that a refractive index decrease of 7 × 10−3 at 633 nm is achieved at a 1 MGy accumulated dose while a photo-induced polymerization occurs, related to the consumption of CH=C, Si-OH and Si-O-CH3 groups to form Ti-O and Si-O bonds. All these results confirm that the host matrix (TiO2-SiO2) and R6G fluorophores successfully withstand the hard γ-ray exposure, opening the way to the use of this material for sensing applications in radiation-rich environments.

Highlights

The sol-gel process is a powerful technique used for the manufacturing of low-cost transparent materials
The sol-gel is widely used in the field of photonics, such as the fabrication of optical waveguides with low losses operating in the telecommunication ranges [7,8] where applications can be found in the aerospace domain [9] or diffraction gratings [10,11] for producing antireflection layers in the solar energy field [12]
The proposed sol-gel is composed by titanium (IV) isopropoxide (TTIP) and 3-(trimethoxysilyl)propyl methacrylate (TMSPMA) acting as titanium and silicate precursors respectively

Summary

Introduction

The sol-gel process is a powerful technique used for the manufacturing of low-cost transparent materials. Based on hydrolysis and condensation reactions [1], this chemistry route clearly evidences its impact by the diversity and abundance of applicative fields Among all these applications, we can mention the development of protective coatings to prevent corrosion phenomena [2,3], sol-gel layers possessing flame-retardant properties [4], gas and pH sensors [5,6]. Using precursors containing an organic chain is of great interest since a UV photosensitivity can be induced while it can be achieved (or enhanced) by incorporation of commercial photoinitiators [13,14] This opens the way to the creation of photopatternable materials by coupling amplitude photomask lithography or direct laser writing techniques [9,15]. Several applications can be found in the literature where the evolution of its luminescent properties can be of interest regarding potential temperature sensing abilities [23] or in more exotic fields such as biomarkers [24]

Objectives

Methods

Results