Mechanosynthesis, Structure and Photoluminescent Properties of the Pr³⁺ Doped LiNbO₃, LiNbO₃:Mg, LiTaO₃ Nanopowders

Abstract

In the current work, nanocrystalline powders with different compositions, namely Li0.98Pr0.02NbO3, Li0.93Pr0.02Mg0.05NbO3 and Li0.98Pr0.02TaO3 were synthesized for the first time using the method of high-energy ball milling of the starting materials (Li2CO3, Nb2O5, Ta2O5, MgO, Pr6O11), followed by high-temperature annealing. XRD data analysis confirmed the absence of parasitic phases in the obtained nanocrystalline compounds. The estimated particle sizes ranged from 20 to 80 nm. From the obtained nanopowders, ceramic samples were prepared using specially developed equipment, which allowed for pressing at elevated temperatures with a simultaneous application of a constant electric field. The obtained photoluminescence spectra exhibit characteristic features of Pr3+ ions in the crystal structure of LiNbO3 and LiTaO3 and are most efficiently excited by UV light. Samples pressed with an electric field application show higher intensity of photoluminescence. Investigations of the temperature dependence of electrical conductivity of the Li0.98Pr0.02NbO3 sample, pressed with the application of an electric field, indicate that the conductivity mechanism is similar to that of LiNbO3 single crystals and, at high temperatures, is attributed to the lithium conduction mechanism.

Keywords

• nanopowders
• lithium niobate
• lithium tantalate
• X-ray diffraction
• photoluminescence
• electroconductivity