Effects of rare earth ion doping on the structural, optical and visible photoluminescent properties of BaTiO₃ perovskite: Spectroscopic-dielectric investigation

In this work, erbium oxide (Er₂O₃), a rare-earth oxide, was employed as a dopant in barium titanate (BaTiO₃) ceramics. The BaTiO₃-based materials were prepared using a conventional solid-state reaction technique. Dopant levels ranging from 0.01 to 1.0 wt.% were incorporated into the ceramic matrix. The prepared samples were sintered at 1380°C for a duration of four hours. The structural, morphological, and optical characteristics of the resulting ceramics were examined using multiple methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and photoluminescence (PL) analysis. For samples with a low Er₂O₃ concentration (0.01 wt.%), grain sizes were found to range between 10 μm and 30 μm. In contrast, increasing the dopant content to 1.0 wt.% inhibited abnormal grain growth, leading to a more refined microstructure with grain sizes in the range of 2 μm to 10 μm. Dielectric properties, including permittivity and loss, were measured as functions of both frequency and temperature in order to establish a relationship between microstructural evolution and dielectric behavior. The amphoteric nature of rare-earth ions was found to enhance dielectric permittivity while reducing dielectric losses compared to undoped BaTiO₃. Furthermore, the effect of dopant concentration on the temperature dependence of the dielectric constant was also evaluated.