A Model for the Hydrothermal Growth of Zinc Oxide Nanorods in a High Solution Concentration Regime
A Model for the Hydrothermal Growth of Zinc Oxide Nanorods in a High Solution Concentration Regime
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DOI：
10.1166/jno.2019.2578
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发表时间：
2019-10-01
影响因子：
0.6
通讯作者：
Flewitt, A. J.
中科院分区：
文献类型：
--
作者：
Ahson, R.;Ahmad, R.;Flewitt, A. J.
水热法生长氧化锌纳米棒已成为一种流行的生长方法。溶液浓度对得到的纳米棒的微观结构有很大的影响，这一点已经在高浓度条件下通过在种子衬底上低温(90℃)生长来研究。用X射线衍射仪和扫描电子显微镜对纳米棒的结构特性进行了表征。讨论了纳米棒的光学和电学性质。扫描电子显微镜图像分析表明，氧化锌纳米棒的直径随着浓度的增加而线性增加，在0.075 M处达到最大值104 nm，之后随着浓度的增加，直径保持不变。当溶液浓度为0.1M时，随着溶液浓度的增加，纳米棒的轴向生长速率增加，纳米棒的长度接近600 nm。与直径的行为相比，纳米棒的数密度表现出相反的行为。纳米棒的电阻率随掺杂浓度的增加而减小，最小值为0.075×10~(-1)欧姆。利用Avrami方程，用成核速率对浓度的依赖关系对生长过程进行了定量模拟。成核速率几乎与溶液浓度无关，说明成核过程是反应受限的。因此，该生长模型可应用于空间位阻较大的其他材料的溶液生长。
Hydrothermal growth has emerged as a popular method for growing ZnO nanorods. Solution concentration can have a significant impact upon the microstructure of the resulting nanorods, and this has been investigated in a high concentration regime by growth at low temperature (90 degrees C) on seeded substrates. X-ray diffraction and scanning electron microscopy (SEM) analyses were used to characterize the structural properties of the ZnO nanorods. Optical and electrical properties of the nanorods are also discussed. SEM image analysis revealed that the ZnO the diameter of nanorods increased linearly with concentration up to a maximum of 104 nm at 0.075 M after which the diameter remained unchanged with further increase in concentration. Axial growth rate was also found to increase with concentration allowing nanorods to achieve lengths of nearly 600 nm for solution concentration of 0.1 M. The number density of nanorods showed inverse behavior as compared to the behavior of the diameter. The resistivity of the nanorods was found to decrease with concentration upto 0.075 M showing a minimum value of 5.85 x 10(-1) Omega-m. The growth process has been quantitatively modelled in terms of the dependence of nucleation rate on concentration using the Avrami equation. The nucleation rate was found to be nearly independent of solution concentration showing that the nucleation process is reaction limited. The growth model may therefore be applied to the solution growth of other materials where steric hindrance is significant.