Effects of yttrium doping on structural, electrical and optical properties of barium titanate ceramics

In this report, we study the Yttrium-doped Barium Titanate (Y-BT) Ba_{1 - x}Y_xTiO₃ (with x = 0.00, 0.01, 0.03, 0.05, 0.07 mmol) perovskite ceramics synthesized by sol-gel method. The as-made powder samples were pressed into a pellet shape and subsequently sintered at 1300 °C for 5 h in air. The structural, morphological, electrical, and optical properties of the synthesized samples were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), impedance analyzer, and UV-Vis-NIR Spectroscopy respectively. The XRD study revealed the formations of single phase tetragonal structure of Barium Titanate (BT) with ∼23-33 nm mean crystallite size. The crystallite size increases initially with Y-doping, found at about 33 nm for x = 0.01, and reduces for increase in Y³⁺ concentration further. The microstructural study from FESEM depicts the uniform distribution of compact and well-faceted grain growth for Y-BT in contrast with undoped barium titanate. The average grain size (∼0.29-0.78 μm) of the Y-BT decreases with increasing doping concentration. Frequency-dependent impedance analyses show enhanced dielectric properties like dielectric constant, quality factor, and conductivity with low dielectric loss in the presence of Yttrium. The optical bandgap energy (∼2.63-3.72 eV) estimated from UV-Vis-NIR diffuse reflection data shows an increasing trend with a higher concentration of yttrium doping.