Hexagonal-shaped NSs are formed which extends to a length of few microns and then narrows like sharpening the pencil and ultimately leads to an elongated core which appears like an exposed

core of pencil. At a glance, having an interesting tail for every structure check details can be observed. The tails look flexible since some are bent like hook while others look slightly bent only. Actually, the NSs are in the process of forming a well-defined shape. It is very likely that the dopant concentration was less than required for the formation of well-defined hexagonal shape. However, the shape itself appears thought-provoking and invites lots of curiosity and zeal for further investigation.Viewing image Figure 6d, it can be well established that a perfect hexagonal NSs looking ‘pencil-like’ have been formed. It can be considered that

2.4 at.% were the possible optimum Selleckchem GPCR Compound Library dopant concentration for the synthesis of the NS. The randomly oriented NS appear well formed and near uniform in size and length. From the EDX analysis, it can be confirmed that Al has been doped into the structure. EDX result shows that 0.08 at.% Al is present in the NS synthesized which can be known from Figure 6b. The sample mapping also indicates that 0.13 at.% Al is present in the sample. To the best of our knowledge, no previous results exhibit such morphology fabricated by thermal evaporation method. Table 1 Varying dopant concentrations selleck antibody at constant temperature, growth time, and flow rate of O 2 Number Growth time

(min) Growth temperature (°C) Flow rate of O2gas (sccm) Dopant concentration (at.%) 1 120 700 200 0 2 120 700 200 0.6 3 120 700 200 1.2 4 120 700 200 2.4 5 120 700 200 4.7 6 120 700 200 11.3 Figure 6 Comparative SEM images of undoped and Al doped ZnO nanowires. (a) 0 at.% Al (undoped), (b) 0.6 at.% Al, (c) 1.2 at.% Al, (d) 2.4 at.% Al, (e) 4.7 at.% Al, and (f) 11.3 at.% Al. When the dopant concentration exceeds beyond 2.4 at.%, the perfect hexagonal shape of the NS are lost. It appears cylindrical in shape with a needle-like extensions from the tips of NRs. The base of NRs appears larger than the tip although at a constant temperature which otherwise if the reaction temperature was raised, the nanowires became thicker because of the enhanced lateral growth [6]. Along with, undefined structures appear in which some look spiky and thorny and others may be nanosheets as in Figure 6e,f which corresponds to 4.7 at.% and 11.3 at.% dopant concentrations, respectively. In the work of Chen et al. [7], further introduction of more Al ions (6 at.%), they obtained network-like nanosheets rather than tubes and rods which was the case for lower dopant concentrations. It is noticeable that beyond 2.4 at.% dopant concentration, it does not contribute to good structural properties of ZnO:Al NWs. We are not very sure if such structures with spiky shapes will have any practical use in any field. ZnO NSs doped with 3 at.