Preparation and study of the titanium oxide thin films doped with Tb3+ and Ce3+ ions

E.F Molina,L.A Rocha,B.L Caetano,E.J Nassar,P.S Calefi,K.J Ciuffi

doi:10.1590/s1517-70762012000100006

Abstract

In this study, we investigated the dependence of the thickness and refractive index of thin films on the withdrawal speed. The films were produced by dip-coating on a glass substrate. The hydrolytic (conventional) sol-gel method was used in the preparation of titanium alkoxide, which were obtained by homogenizing tetraethylorthotitanate stabilized by beta-diketone (2,4-pentanodione) in an alcohol solution. Potential applications, such as active planar waveguides, were evaluated by m-line spectroscopy, electron absorption spectra in the ultraviolet visible region, and photoluminescence. Based on the m-line measurements, the thickness of the films obtained from the homogenized sols were found to be dependent on the withdrawal speed. The thickness range from 400 to 500 nm to the films prepared by withdrawal speed 100 mm/min, 600 to 700nm using 200 mm/min, and 800 to 900 nm to withdrawal speed 300 mm/min. The refractive index is not affected by deposition speed. The photoluminescence of the Tb III ion exhibited lines that were attributed to the transitions characteristic of this ion, i.e., transitions from the 5D4 excited state to the 7FJ (J=3,4,5,6) fundamental state.

Highlights

The development of techniques based on the production of thin films applied to materials science is one of the major factors responsible for technological advances 1
The films’ refractive index varied little, regardless of the withdrawal speed and dopants used, this is an indicative that rare earths ions is not affected by the titanium oxide structure
The refractive index is very important in applications such as waveguides

Summary

INTRODUCTION

The development of techniques based on the production of thin films applied to materials science is one of the major factors responsible for technological advances 1. Thin films doped with rare earth ions to obtain materials with luminescent properties offer unique advantages, such as easy doping and control of the concentrations of dopant 6. Various studies have been conducted to obtain information about the morphology, thermal stability and spectroscopic properties of thin films, such as luminescence and life span of excited states 7, 8. These thin films have engendered much interest due to the variety of possible applications, which include optical 9 and electroluminescent 10, 11 devices, sensors 12, 13 , biomaterials 14-16 and others 17. The films, obtained by dip-coating at different withdrawal rates and containing Tb3+ only and Tb3+ and Ce3+ ions, were characterized by m-line measurements, by the photoluminescence of the Tb3+ ions, and UV-Vis absorption spectroscopy

MATERIALS AND METHODS

RESULTS AND DISCUSSION

CONCLUSION