Spectroscopic and crystal field study of Sm³⁺in different phases of TiO₂

Abstract

A systematic study of the photoluminescence spectra of samarium-doped crystalline TiO2 was conducted within the temperature range 10–300 K in order to reveal the energy levels of the trivalent impurity ion in different phases of titania. The sol–gel route was used to prepare Sm-doped TiO2 powders. The nanocrystalline anatase phase was obtained by annealing up to 800 °C, whereas the rutile phase was developed by annealing above 1000 °C. Crystal field calculations of Sm3+ energy levels in the two phases of TiO2 (anatase and rutile) were performed for the first time. The obtained set of energy levels assuming positioning of the Sm3+ ions in regular TiO2 lattice sites was consistent with the experimental results. The effect of the different phases of titania on the impurity is discussed.