Influence of Er3+ concentration and sintering temperature on structural and spectroscopic properties of BaTiO3:Er3+

This study analyzes the effects of doping BaTiO3 with Er3+ within its perovskite ABO3 structure, specifically investigating how substituting Er3+ at the Ba (A-site) and Ti (B-site) locations influences the material at different doping levels. Scanning electron microscopy (SEM)/energy-dispersive X-ray spectrometry (EDS) analysis shows that all of the samples have polygonal grains. In BTO doped with 0.01 wt% and 0.1 wt% Er3+ grain size was up to 45 μm. With the higher amount, the growth is slowing down and grains are 2–10 μm. Raman spectra show part of common BaTiO3 modes only for the lowest content of Er3+. At higher Er3+ content, the usual modes are completely covered by strong luminescence originating from Er3+ deexcitation from energy level 2H11/2. The intensity of the photoluminescence (PL) bands shows the influence of not only the Er3+ concentration, but also the crystallinity of the sample, especially their surface. The FIR reflectivity shows а slight wavelength shift for higher sintering temperature, but all spectra show lower intensity comparing with pure BaTiO3. FTIR transmission spectra show slight shifts of characteristic Ti–O bending mode at about 480 cm−1 confirming the incorporation of Er3+ in BaTiO3 at 1320 °C and 1350 °C. Near IR excitation (1530 nm) provoked upconversion photoluminescent (UCPL) spectra of BaTiO3:Er3+ with PL lines at higher energies. The upconversion mechanism for each line was determined and the fluorescence lifetime was estimated. It is observed that the obtained intensities of UCPL increase gradually at both sintering temperatures with increase of Er3+ content. © 2024 Elsevier B.V.