Batool S S, Imran Z, Rasool Kamran, Ambreen Jaweria, Hassan Safia, Arif Saira, Ahmad Mushtaq, Rafiq M A
Department of Physics, COMSATS University Islamabad, Park Road, Chak Shahzad, Islamabad, 45550, Pakistan.
Micro and Nano Devices Group, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), P. O. Nilore, Islamabad, 4650, Pakistan.
Sci Rep. 2020 Feb 17;10(1):2775. doi: 10.1038/s41598-020-59563-6.
This work represents the nature of conduction mechanism in bismuth silicate (BiSiO) nanofibers as a function of temperature and frequency. Scanning electron micrographs and X-rays diffraction patterns exhibited the formation of cubic phases of Bi(SiO) and BiSiO nanofibers respectively with an average diameter of ~200 nm. Temperature dependent (300 K-400 K) electrical characterization of fibers was carried out in frequency range of ~20 Hz-2 MHz. The complex impedance analysis showed contribution from bulk and intergranular parts of nanofibers in conduction. Moreover, analysis of the Cole-Cole plot confirmed the space charge dependent behavior of BiSiO nanofibers. Two types of relaxation phenomena were observed through Modulus analysis. In ac conductivity curve, step like feature of plateau and dispersive regions were described by Maxwell-Wagner effect while the dc part obeyed the Arrhenius law. However, frequency dependent ac conductivity revealed the presence of conduction mechanism in diverse regions that was ascribed to large polaron tunneling model. Detailed analysis of complex Impedance and ac conductivity measurement showed negative temperature coefficient of resistance for the BiSiO nanofibers. Current-voltage (IV) characteristics represented ohmic conduction; followed by space charge limited current conduction at intermediate voltages. Results from both ac and dc measurements were in good agreement with each other.
这项工作揭示了硅酸铋（BiSiO）纳米纤维中传导机制的性质与温度和频率的关系。扫描电子显微镜图像和X射线衍射图谱分别显示了Bi(SiO)和BiSiO纳米纤维立方相的形成，其平均直径约为200nm。在约20Hz - 2MHz的频率范围内，对纤维进行了温度依赖型（300K - 400K）电学特性表征。复阻抗分析表明，纳米纤维的体相和晶界部分对传导均有贡献。此外，科尔 - 科尔图分析证实了BiSiO纳米纤维的空间电荷依赖行为。通过模量分析观察到两种弛豫现象。在交流电导率曲线中，平台和色散区域的阶梯状特征由麦克斯韦 - 瓦格纳效应描述，而直流部分遵循阿仑尼乌斯定律。然而，频率依赖的交流电导率揭示了不同区域存在传导机制，这归因于大极化子隧穿模型。对复阻抗和交流电导率测量的详细分析表明，BiSiO纳米纤维具有负电阻温度系数。电流 - 电压（IV）特性表现为欧姆传导；随后在中等电压下为空间电荷限制电流传导。交流和直流测量结果彼此吻合良好。
