Doping-Induced Relaxor Ferroelectricity and Site Engineering in Ba_1–<i>x</i>Pr_2<i>x</i>/3Ti_1–<i>y</i>(Mo_1/2Nb_1/2)_<i>y</i>O₃ Ceramics for Enhanced Permittivity and Energy Sto

In this study, site engineering at the Ba and Ti sites of BaTiO₃ has been done to develop Ba_1-<i>x</i> Pr_2<i>x</i>/3Ti_1-<i>y</i> (Mo_1/2Nb_1/2) _<i>y</i> O₃ [BTMN] ceramics, with <i>x</i> = 0.003 and <i>y</i> = 0.02, 0.04, 0.06, 0.08, 0.1, to improve permittivity and energy storage performance. The solid-state reaction method was used to synthesize samples. X-ray diffraction analysis revealed a crystallographic phase transition from tetragonal (<i>P</i>4<i>mm</i>) to cubic (<i>Pm</i>-3<i>m</i>) structure with increasing (Mo_1/2Nb_1/2) concentration. Raman spectroscopy further validates this finding with the disappearance of the characteristic tetragonal peak at 303 cm^-1 for higher dopant levels (<i>y</i> ≥ 0.06). Grain size displays a nonlinear trend where grain size first increases to 0.49 μm for intermediate compositions and then decreases to 0.25 μm at higher dopant levels. Dielectric characterization revealed that the increased relative permittivity (ε_r = 2840.46 at 20 Hz) and low dielectric loss (0.0390) have been achieved for the BTMN06 sample, and all other compositions exhibited low dielectric loss (<0.055) in the frequency range 20 Hz to 100 kHz. Permittivity decreased with increasing frequency, which is consistent with Maxwell-Wagner polarization effects. Curie temperature (<i>T</i> _c) shifted downward from 115 °C (BTMN02) to 31 °C (BTMN10), reflecting increased structural disorder induced by doping. Relaxor behavior was quantified by an increasing diffusion parameter (1.28 to 1.95) for permittivity, with enhanced polarization stability and slim P-E hysteresis loops at higher dopant levels. Energy storage characteristics showed superior recoverable energy densities (317.7 mJ/cm³ for BTMN08 and 292.2 mJ/cm³ for BTMN10 with efficiencies 91 and 92.6% respectively), validating the material's potential for high-efficiency capacitive energy storage in advanced applications.