Effect of Eu³⁺ doping on the structural and photoluminescence properties of cubic CaCO₃

Graphical abstract: - Highlights: • The doping of Eu³⁺ ions decreased the size of CaCO₃ nanoparticles. • The doping of Eu³⁺ ions brought about the change of CaCO₃'s optical bandgap. • Multiple sites of Eu³⁺ in CaCO₃ nanocrystals have been identified. - Abstract: CaCO₃:xEu³⁺ (x = 0, 0.010, 0.015, 0.020, and 0.025) cubic nanoparticles were synthesized by carbonation method. The powder XRD patterns and SEM images of the CaCO₃:xEu³⁺ nanoparticles demonstrate that both the crystalline sizes and average particle sizes of synthesized samples decreased with the increase of Eu³⁺ content until x = 0.020. Kubelka–Munk plots and bandgap energy estimation indicate that the doping of Eu³⁺ ions changed optical bandgap of CaCO₃. Photoluminescence (PL) spectra show that the PL intensity of the CaCO₃:xEu³⁺ nanoparticles was enhanced with the increase of Eu³⁺ content in cubic CaCO₃:xEu³⁺, and concentration quenching occurred when Eu³⁺ concentration exceeded 2.0 mol%. In addition, the doped sites of Eu³⁺ in CaCO₃ crystalline were identified by the site-selective spectroscopy and decay curves.