Hadded Abir, Massoudi Jalel, Dhahri Essebti, Khirouni Kamel, Costa B F O
Laboratory of Applied Physics, Faculty of Sciences, University of Sfax B. P. 1171 Sfax 3000 Tunisia
Laboratory of Physics of Materials and Nanomaterials Applied to the Environment, Faculty of Sciences of Gabes Cité Erriadh, University of Gabès 6079 Gabès Tunisia.
RSC Adv. 2020 Nov 23;10(69):42542-42556. doi: 10.1039/d0ra08405k. eCollection 2020 Nov 17.
In this study, a CuMnO spinel was successfully synthesized by a sol-gel method at 500 °C for 5 h and characterized by different techniques. X-ray diffraction (XRD), Fourier transformation infrared (FTIR) spectroscopy and Raman spectroscopic analyses confirmed the formation of a spinel cubic structure with the 3̄ space group. The SEM proves that the grain size of our compound is of the order of 48 nm. Crystallite sizes determined from three estimates are closer to the grain size obtained from the SEM, indicating the single domain nature of the sample. The optical properties of UV-visible spectroscopy for our sample showed that the gap value is equal to 3.82 eV, making our compound a good candidate for optoelectronic applications. For electrical properties, impedance spectroscopy was performed at a frequency range of 40 ≤ frequency ≤ 10 Hz. This suggested hoping conduction due to three theoretical models. The latter can be attributed to the correlated barrier hopping (CBH) model in region I, overlapping large polaron tunneling (OLPT) in region II and non-overlapping small polaron tunneling (NSPT) mechanism in region III. One dielectric relaxation is detected from the dielectric impedance and modulus, attributed to grain contributions. This behavior was confirmed by both Nyquist and Argand's plots of dielectric impedance at different measuring temperatures.
在本研究中，通过溶胶-凝胶法在500℃下成功合成了CuMnO尖晶石，并对其进行了5小时的处理，然后采用不同技术对其进行表征。X射线衍射（XRD）、傅里叶变换红外（FTIR）光谱和拉曼光谱分析证实形成了具有3̄空间群的尖晶石立方结构。扫描电子显微镜（SEM）证明我们化合物的晶粒尺寸约为48nm。通过三种估算方法确定的微晶尺寸更接近从扫描电子显微镜获得的晶粒尺寸，表明样品具有单畴性质。我们样品的紫外可见光谱光学性质表明能隙值等于3.82eV，这使我们的化合物成为光电子应用的良好候选材料。对于电学性质，在40≤频率≤10Hz的频率范围内进行了阻抗谱测量。这表明由于三种理论模型存在霍普导电现象。后者可归因于区域I中的相关势垒跳跃（CBH）模型、区域II中的重叠大极化子隧穿（OLPT）和区域III中的非重叠小极化子隧穿（NSPT）机制。从介电阻抗和模量中检测到一种介电弛豫，这归因于晶粒的贡献。在不同测量温度下，奈奎斯特图和介电阻抗的阿尔冈图均证实了这种行为。
