Abstract This work highlights some physical investigations on NiFe2O4/ α- Fe2O3 composite deposited on glass substrates as thin films at T=460°C by the spray pyrolysis technique. First, X-ray diffraction analysis approved the polycrystalline nature of such films with a mixture of NiFe2O4 and α- Fe2O3 materials. The majority phase based on NiFe2O4 compound indicated the achievement of a cubic structure and the preferred orientation of the crystallites are along (311) direction while α- Fe2O3 is a minority phase crystallizing in rhombohedra structure. Raman spectroscopy measurement depicts the presence of cubic structure of NiFe2O4. Moreover, the reflectance and the transmittance optical coefficients increase with wavelength and do not exceed 45% which reveals an absorbent character of these films. Second, we evaluated the electrical properties of such films at various temperatures (430-490°C) by using the impedance spectroscopy technique in frequency range of 5 Hz–13 MHz. Both the DC conductivity and relaxation frequency were thermally activated with an activation energy around 0.67 eV. Also, AC conductivity was estimated and deeply discussed through Jonscher law. Nonetheless, the electropyroelectric study of these films has been made and discussed. Also, the wettability experiments have been carried out regarding the contact angle CA which reveals a hydrophilic nature of NiFe2O4/ α- Fe2O3 sprayed thin films. Finally, the photocatalytic activity of these films were carried out regarding the photodegradation of methylene bleu (MB) under sunlight during 120 min.

中文翻译：

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NiFe2O4/α-Fe2O3复合薄膜的物理研究潜在应用

摘要 这项工作重点介绍了通过喷雾热解技术在 T=460°C 下沉积在玻璃基板上作为薄膜的 NiFe2O4/α-Fe2O3 复合材料的一些物理研究。首先，X 射线衍射分析证实了这种具有 NiFe2O4 和 α-Fe2O3 材料混合物的薄膜的多晶性质。基于NiFe2O4化合物的主要相表明获得了立方结构，并且微晶的择优取向沿（311）方向，而α-Fe2O3是在菱面体结构中结晶的少数相。拉曼光谱测量描述了 NiFe2O4 立方结构的存在。此外，反射率和透射率光学系数随波长增加并且不超过 45%，这表明这些薄膜具有吸收特性。第二，我们通过使用阻抗谱技术在 5 Hz-13 MHz 的频率范围内评估了此类薄膜在各种温度（430-490°C）下的电性能。直流电导率和弛豫频率都被热激活，激活能约为 0.67 eV。此外，还通过 Jonscher 定律估算并深入讨论了交流电导率。尽管如此，已经对这些薄膜进行了电热释电研究并进行了讨论。此外，已经对接触角 CA 进行了润湿性实验，这揭示了 NiFe2O4/α-Fe2O3 喷涂薄膜的亲水性。最后，这些薄膜的光催化活性是关于亚甲基蓝（MB）在阳光下在 120 分钟内的光降解。