Sol‐gel route to nanocrystalline Eu2Ti2O7 films with tailored structural and optical properties

Abstract

AbstractWe present a generic sol‐gel approach for the preparation of highly transparent europium titanate Eu2Ti2O7 films with tailored structural and optical properties. The films were prepared by a sol‐gel process and thermally treated in a rapid thermal annealing furnace. We determined the effects of the annealing temperature on structural, morphological, and optical properties of the films. We evaluated film's optical constants. The size of the primary nanocrystals and the film's refractive index were tailored by the annealing temperature. The crystallization of Eu2Ti2O7 started at 800°C and the nanocrystals grew with increasing annealing temperature reaching the size from 20 nm to 100 nm. The energy of nanocrystal growth was 21 ± 3 kJ·mol−1. Increasing nanocrystal size caused the regular growth of the refractive index recorded at 632 nm from 2.07 to 2.17 for the films annealed at 800°C and 1200°C, respectively. These results provide fundamental information about the effects of the structure and the morphology of the films on their optical properties. The presented approach can be extended to other rare earth‐doped titanates and these films can be used as passive protective coatings as well as active materials suitable for photonic and spintronic applications.