Ouertani A, Abdelkafi Z, Khemakhem H, Randrianantoandro N
Laboratory of Multifunctional Materials and Applications (LaMMA), LR16ES18, Faculty of Sciences of Sfax, University of Sfax B.P. 1171 Sfax 3000 Tunisia
Institut des Molécules et Matériaux du Mans - UMR 6283, CNRS - Le Mans Université Avenue Olivier Messaien Le Mans 72085 France.
RSC Adv. 2024 Apr 29;14(20):14080-14090. doi: 10.1039/d4ra01850h. eCollection 2024 Apr 25.
The environmentally friendly BiFe(TiCu)O system with various substitution rates, including = 0 (BFO), = 0.02 (BFTCO) and = 0.04 (BFTCO), has been synthesized using the solid-state reaction technique. All compositions exhibited a distorted rhombohedral structure with 3 space, as observed from the results of XRD and Raman spectroscopy. A significant impurity phase (BiFeO) appears in pure and doped BFO, with a percentage ranging between 6 and 9%. This impurity was also detected using Mössbauer spectroscopy. UV-vis spectroscopy revealed a decrease in optical band energy with the substitution, suggesting the potential applications of doped BFO within the visible range of the spectrum, making it suitable for photocatalytic and solar cell applications. The smallest bandgap was observed for BFTCO with = 1.93 eV. The origin of this reduction is discussed from a scientific point of view. Furthermore, Cu and Ti co-doped BFO display an improvement in dielectric properties due to the reduction in the value of tan . Dielectric measurements revealed an anomaly below with diffusive and dispersive behavior, suggesting a relaxor-like behavior for all compositions. The relaxor character was quantified by using the Vogel-Fulcher relationship which yielded activation energy of 0.359-0.614 eV. In our system, the relaxor behavior showed an enhancement with the heterogeneity created by the substitution rate, reaching its maximum for BFTCO, characterized by the empirical parameters which are: Δ = 96 K and = 1.96. Finally, co-doped BFO ceramics not only present promising materials for optical applications due to the narrow bandgap, but their relaxor behavior can also be tailored for promising applications in high-energy storage devices.
采用固态反应技术合成了具有不同取代率的环保型BiFe(TiCu)O体系，其中取代率 = 0（BFO）、 = 0.02（BFTCO）和 = 0.04（BFTCO）。从XRD和拉曼光谱结果观察到，所有成分均呈现具有3种空间群的畸变菱面体结构。在纯BFO和掺杂BFO中出现了显著的杂质相（BiFeO），其百分比在6%至9%之间。该杂质也通过穆斯堡尔光谱检测到。紫外可见光谱显示，随着取代作用，光学带隙能量降低，这表明掺杂BFO在光谱的可见光范围内具有潜在应用，使其适用于光催化和太阳能电池应用。对于 = 1.93 eV的BFTCO，观察到最小带隙。从科学角度讨论了这种降低的起源。此外，由于tan 值的降低，Cu和Ti共掺杂的BFO的介电性能有所改善。介电测量显示在 以下存在具有扩散和色散行为的异常，表明所有成分都具有类弛豫行为。通过使用Vogel-Fulcher关系对弛豫特性进行了量化，得到的激活能为0.359 - 0.614 eV。在我们的体系中，弛豫行为随着取代率产生的不均匀性而增强，在BFTCO中达到最大值，其特征经验参数为：Δ = 96 K和 = 1.96。最后，共掺杂BFO陶瓷不仅因其窄带隙而成为有前景的光学应用材料，而且其弛豫行为也可针对高能存储器件中的有前景应用进行调整。
