Sol-gel based design of lead-free yttrium-doped barium titanate nanocomposites for advanced functional materials

Nano-structured pure BaTiO 3 (B-T) and BaTiO 3 doped with different concentrations of yttrium ranging from 1 to 10 mol.%, coded as [BYT-x (x = 0–10)], were prepared using a modified sol-gel process. The study utilized X-ray diffraction (XRD) to illustrate the tetragonal structure of the perovskite BaTiO 3 . The persistence of the tetragonal phase was further verified using a mathematical derivative-based investigation. High resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) were used to examine the morphology of the doped samples. The results indicated that the crystallite size estimated using XRD ranged from 23.36 to 37.84 nm. Two complementary precision impedance measuring instruments were used to properly assess the dielectric characteristics across a wide frequency range (42 Hz to 1 GHz), guaranteeing good measuring accuracy across various regimes. Dielectric characterization of the yttrium-doped BaTiO 3 over such an extended frequency range remains scarcely reported. The dielectric measurements were carried out using a 3532-50 LCR Hi-TESTER and a network impedance analyzer (KEYSIGHT-E4991B), respectively. The pure sample (BYT-0) exhibited a significant permittivity ( ~ 770) and a tangent loss ( ~ 0.076), whereas the doped sample (BYT-9) showed a reduced permittivity (ε′ ~ 95) along with a significantly lower tangent loss (tan(δ) ~ 0.015). Yttrium doping significantly enhances the self-resonance frequency (SRF), thereby expanding the operational frequency range toward high-frequency applications. Consequently, the tailored dielectric characteristics of the yttrium-doped samples make them promising candidates for miniaturized microwave applications.