熔盐法合成的Na0.5Bi0.5TiO3和Na0.25Bi0.25Ba0.5TiO3钙钛矿中Ba2+掺杂对结构、介电及储能特性影响的比较分析

Perovskite samples of Na 0.5 Bi 0.5 TiO 3 (NBT) and Na 0.25 Bi 0.25 Ba 0.5 TiO 3 (NBBT) were synthesized using the molten-salt method. The structural, morphological, and electrical properties of these materials were analyzed. Both samples exhibited a single-phase rhombohedral crystal structure with space group R 3 c . Rietveld refinement confirmed an increase in unit cell volume upon Ba doping, attributed to the larger ionic radius of Ba 2 ⁺ compared to Na⁺ and Bi 3 ⁺. FTIR spectra showed shifts in the Ti–O bond vibrations, indicating elongation of the bond in NBBT. SEM analysis revealed plate-like, anisotropic grains with reduced grain size following Ba substitution. Both NBT and NBBT samples exhibit ferroelectric behavior, which is primarily influenced by the overall structural distortion, particularly the tilting of the TiO₆ octahedra and A -site cation shifting. NBBT exhibited more pronounced relaxor ferroelectric behavior than NBT since the Ba 2 ⁺ doping led to significant compositional disorder, disrupting long-range ferroelectric order and enhancing relaxor behavior. As a result, NBBT exhibits better energy storage performance, with a recoverable energy storage density ( W rec ) of 21.56 mJ/cm 3 and an energy efficiency (η) of 94.21% at a low electrical field of 35 kV/cm. These results highlight the crucial role of structural distortions and compositional disorder in driving the enhanced relaxor ferroelectric behavior in NBBT, positioning it as a promising candidate for energy storage applications.