Issue 60, 2017, Issue in Progress

Structure-property relationships for Eu doped TiO2 thin films grown by a laser assisted technique from colloidal sols

Abstract

Photoactive europium doped titanium dioxide (Eu:TiO2) thin films were grown by a matrix assisted pulsed laser evaporation technique. TiO2 and Eu cation-adsorbed TiO2 nanoparticles (NPs) sols were used as starting materials. The sols were synthesized by a colloidal sol–gel route. In order to obtain solid targets, the sols were cooled down until solidification in liquid nitrogen. The irradiation of the solid targets was performed in a controlled oxygen atmosphere using an UV KrF* (λ = 248 nm, τFWHM ≤ 25 ns, ν = 10 Hz) excimer laser source. The NPs were transferred and deposited onto solid substrates placed in the front of the frozen targets, forming continuous thin films. The as-grown undoped and Eu:TiO2 thin films were submitted to post-deposition thermal treatments. The surface morphology, crystalline structure, and chemical composition of the thin films were characterized by field emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Functional optical properties of the films were investigated by UV-VIS-NIR spectroscopy, spectroscopic ellipsometry, and photoluminescence as a function of dopant concentration in the TiO2 host and annealing temperature. A direct correlation was established between the processing conditions, films structure, chemical composition and oxidation states studied both at the top surface and in-depth as well as their functional, optical properties. Eu doping induces a blue-shift of the absorption edge with respect to the as-grown samples. Under visible light excitation (λ = 488 nm, emitted by an Ar+ laser source), the Eu:TiO2 samples show characteristic photoluminescence corresponding to the 5D07Fi (i = 0, 1, 2, 3, 4) transitions of Eu+ ions in the visible spectral range. The samples treated at the highest annealing temperature are characterized by strong photoluminescence emission, high transmittance in the VIS-NIR spectral regions, and high refractive index.

Graphical abstract: Structure-property relationships for Eu doped TiO2 thin films grown by a laser assisted technique from colloidal sols

Article information

Article type
Paper
Submitted
05 May 2017
Accepted
21 Jul 2017
First published
31 Jul 2017
This article is Open Access
Creative Commons BY license

RSC Adv., 2017,7, 37643-37653

Structure-property relationships for Eu doped TiO2 thin films grown by a laser assisted technique from colloidal sols

I. Camps, M. Borlaf, M. T. Colomer, R. Moreno, L. Duta, C. Nita, A. Perez del Pino, C. Logofatu, R. Serna and E. György, RSC Adv., 2017, 7, 37643 DOI: 10.1039/C7RA05074G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements