Rare earth titanates ceramics Na2La2Ti3O10: Pr3+ and RE2Ti2O7: Pr3+ (R = Gd, Y): sol–gel synthesis, characterization and luminescence

In this work, rare earth (La, Gd, Y) titanate ceramics have been synthesized with a sol–gel process of Ti(OC4H9)4 precursor. It is found that these titanates of the three rare earth ions present two different typical phase composition and crystal structure in spite of the same reaction ratio of the precursors and synthesis conditions, which is taken in the formula Na2La2Ti3O10, and RE2Ti2O7 (RE = Gd, Y), respectively. Besides, the microstructure (particle size and morphology) also show different features for different titanates by SEM. Subsequently, the optical properties (such as ultraviolet–visible diffuse reflectance absorption and photoluminescence) of these titanates activated with Pr3+ Na2La2Ti3O10: x mol % Pr3+ (x = 0, 0.2, 2, 5, 10, 15), and RE2Ti2O7: x mol % Pr3+ (RE = Gd and Y) (both x = 0, 0.2) are compared to study. Especially Na2La2Ti3O10: Pr3+ is selected as an example to check that the concentration effect on the luminescence of Pr3+, revealing that Na2La2Ti3O10: 0.2 mol % Pr3+ possesses the strongest emission.