Pseudobrookite of general formula PbBaFeO was synthesized by the sol–gel route. X-ray diffraction confirms the orthorhombic space group of our sample. UV–Vis absorption spectroscopy was used to characterize this material's optical properties. We used the Tauc model and absorption measurements to estimate the direct optical band gap at 3.53 eV. We also calculate the Urbach energy, the optical extinction coefficient, and the refractive index. In addition, the skin depth, optical conductivity, and Cauchy parameters were investigated in relation to the incident photon's wavelength. Electrical conductivity data flow the Jonscher's power law and show that PBFO has two different conducts; Semiconductor behavior in the temperatures region [400 K–520 K]. Then, a metallic trend was detected beyond T = 520 K. The correlated barrier hopping (CBH) model is the appropriate model to describe the conduction process in low temperature range. On the other hand, the conduction is ensured by the non-overlapping small polaron tunneling (NSPT) at high temperature zone. The scaling study shows that the conductivity spectra deviate from Summerfield and Ghosh scaling. The random barrier model (RBM) is employed to correct the Summerfield approach and we note that the conductivity isotherms are combined into a single master curve. The estimated activation energies values from dc-conductivity, hopping frequency and relaxation time are very close. The behavior of dielectric parameters was examined using the Maxwell-Wagner theory of interfacial polarization. The dielectric-relaxation phenomenon is shown by the behaviors of imaginary parts of impedance (Z″) and modulus (M″). The ideal electrical equivalent circuit for simulating the Nyquist curves (i.e. Z′′(Z′)) for our pseudobrookite is (R + R//CPE). Finally, the entropy (ΔS), and enthalpy (ΔH) were established as thermodynamic parameters.

中文翻译：

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溶胶-凝胶法合成铁板钛矿Pb0·5Ba0·5Fe2O5的结构、光学和阻抗谱

采用溶胶-凝胶法合成了通式为 PbBaFeO 的铁板钛矿。 X 射线衍射证实了我们样品的斜方空间群。紫外-可见吸收光谱用于表征该材料的光学特性。我们使用 Tauc 模型和吸收测量来估计 3.53 eV 处的直接光学带隙。我们还计算了乌尔巴赫能量、消光系数和折射率。此外，还研究了趋肤深度、光导率和柯西参数与入射光子波长的关系。电导率数据遵循 Jonscher 幂律，表明 PBFO 有两种不同的行为；温度范围 [400 K–520 K] 中的半导体行为。然后，在 T = 520 K 之外检测到金属趋势。相关势垒跳跃 (CBH) 模型是描述低温范围内传导过程的合适模型。另一方面，高温区的非重叠小极化子隧道效应（NSPT）保证了导通。标度研究表明电导率谱偏离 Summerfield 和 Ghosh 标度。采用随机势垒模型 (RBM) 来校正萨默菲尔德方法，我们注意到电导率等温线被组合成一条主曲线。根据直流电导率、跳跃频率和弛豫时间估计的活化能值非常接近。使用麦克斯韦-瓦格纳界面极化理论检查介电参数的行为。介电弛豫现象通过阻抗（Z”）和模量（M”）虚部的行为来表现。用于模拟铁板钛矿的奈奎斯特曲线（即 Z′′(Z′)）的理想电气等效电路是 (R + R//CPE)。最后，建立熵（ΔS）和焓（ΔH）作为热力学参数。