Samir Hager, Taha Mohamed, El-Dek S I, Zaki Ayman H
Materials Science and Nanotechnology Department, Faculty of Postgraduate Studies for Advanced Sciences, Beni-Suef University, Beni-Suef 2722165, Egypt.
ACS Omega. 2022 Jul 26;7(31):27587-27601. doi: 10.1021/acsomega.2c03170. eCollection 2022 Aug 9.
Sodium titanate nanotubes (Na-TNTs) and their metal-doped derivatives were prepared using simple hydrothermal and metal ion-exchange methods, respectively. The as-prepared doped materials were characterized by X-ray powder diffraction, thermal gravimetric analysis, high-resolution transmission electron microscopy, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The dielectric constant, the loss tangent, and the AC electrical conductivity of NaM-TNTs (where M = Cr, Cu, Ni, or Zn) were measured at selected frequencies (400 kHz and 2 MHz) as a function of temperature. The activation energy was calculated and reported at 400 kHz. All samples showed mixed ionic electronic conductivity. Some of the materials were used as examples for theoretically exploring structures and optoelectronic properties (density of states, reflectivity, absorption curve, refractive index, dielectric function, optical conductivity, and loss function) using density functional theory calculations. The band gaps of the materials were found to vary from 2.4 to 3.17 eV, which makes them suitable for many optoelectronic applications.
钛酸钠纳米管（Na-TNTs）及其金属掺杂衍生物分别采用简单的水热法和金属离子交换法制备。通过X射线粉末衍射、热重分析、高分辨率透射电子显微镜、场发射扫描电子显微镜和能量色散X射线光谱对所制备的掺杂材料进行了表征。在选定频率（400 kHz和2 MHz）下测量了NaM-TNTs（其中M = Cr、Cu、Ni或Zn）的介电常数、损耗角正切和交流电导率随温度的变化。计算并报告了400 kHz下的活化能。所有样品均表现出混合离子电子传导性。使用密度泛函理论计算，以其中一些材料为例，从理论上探索了结构和光电性质（态密度、反射率、吸收曲线、折射率、介电函数、光导率和损耗函数）。发现这些材料的带隙在2.4至3.17 eV之间变化，这使其适用于许多光电应用。
