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Arc Discharge Synthesis and Photoluminescence of 3D Feather-like AlN Nanostructures

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ABSTRACT

A complex three-dimensional (3D) feather-like AlN nanostructure was synthesized by a direct reaction of high-purity Al granules with nitrogen using an arc discharge method. By adjusting the discharge time, a coral-like nanostructure, which evolved from the feather-like nanostructure, has also been observed. The novel 3D feather-like AlN nanostructure has a hierarchical dendritic structure, which means that the angle between the trunk stem and its branch is always about 30° in any part of the structure. The fine branches on the surface of the feather-like nanostructure have shown a uniform fish scale shape, which are about 100 nm long, 10 nm thick and several tens of nanometers in width. An alternate growth model has been proposed to explain the novel nanostructure. The spectrum of the feather-like products shows a strong blue emission band centered at 438 nm (2.84 eV), which indicates their potential application as blue light-emitting diodes.

No MeSH data available.


A scheme of the alternate growth mechanism.  is the direction perpendicular to (103) and  is perpendicular to (0001). The theoretical angle (α1,2,3) between the trunk and its branches is 31.65°.
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Figure 5: A scheme of the alternate growth mechanism. is the direction perpendicular to (103) and is perpendicular to (0001). The theoretical angle (α1,2,3) between the trunk and its branches is 31.65°.

Mentions: An alternate growth model has been proposed to explain the novel nanostructure as illustrated in Figure 5. The arc discharge reaction growth should be a VS process. When arc discharge begins, activate Al and N atoms will be continuously generated near the surface of the Al ingot, and a pit will appear immediately as a molten pool. After intense reaction, a lot of AlN crystals will nucleate on the inter surface of the pit. As the (0001) plane of h-AlN is the most close-packed plane,a growth along [0001] direction follows the principle of minimum energy. Nevertheless, the growth is under the control of thermodynamic and kinetic principles simultaneously. During arc discharge, the reaction temperature will be about 2,400–3,000 K and the pressure will become above 1.3 × 105 Pa, which means that the growth process is non-equilibrium and supersaturated. Thus, some oblique growth (perpendicular to the {103} of h-AlN) will happen, which can supply more growth space and high growth speed. Meanwhile, growth along [0001] direction appears on the oblique branches, which means that the nanostructure is formed by an alternate growth along two crystal directions. It should be a balance of the crystal stability and growth speed. The good symmetrical morphology of feather-like nanostructures might originate from the symmetry of the alternate growth model as shown in Figure 5. The outer branch tips had more chance collecting molecules, so more fine structures (like fish scale) were found on the surface, and void was generated by shadowing effect. It should be emphasized that Figure 5 is a simplified 2D diagram, whereas the real branches will grow in a 3D space, which should lead to the complex 3D feather-like nanostructure. Nevertheless, a perfect explanation of the 3D feather-like AlN nanostructures still needs more detailed and direct evidences.


Arc Discharge Synthesis and Photoluminescence of 3D Feather-like AlN Nanostructures
A scheme of the alternate growth mechanism.  is the direction perpendicular to (103) and  is perpendicular to (0001). The theoretical angle (α1,2,3) between the trunk and its branches is 31.65°.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211165&req=5

Figure 5: A scheme of the alternate growth mechanism. is the direction perpendicular to (103) and is perpendicular to (0001). The theoretical angle (α1,2,3) between the trunk and its branches is 31.65°.
Mentions: An alternate growth model has been proposed to explain the novel nanostructure as illustrated in Figure 5. The arc discharge reaction growth should be a VS process. When arc discharge begins, activate Al and N atoms will be continuously generated near the surface of the Al ingot, and a pit will appear immediately as a molten pool. After intense reaction, a lot of AlN crystals will nucleate on the inter surface of the pit. As the (0001) plane of h-AlN is the most close-packed plane,a growth along [0001] direction follows the principle of minimum energy. Nevertheless, the growth is under the control of thermodynamic and kinetic principles simultaneously. During arc discharge, the reaction temperature will be about 2,400–3,000 K and the pressure will become above 1.3 × 105 Pa, which means that the growth process is non-equilibrium and supersaturated. Thus, some oblique growth (perpendicular to the {103} of h-AlN) will happen, which can supply more growth space and high growth speed. Meanwhile, growth along [0001] direction appears on the oblique branches, which means that the nanostructure is formed by an alternate growth along two crystal directions. It should be a balance of the crystal stability and growth speed. The good symmetrical morphology of feather-like nanostructures might originate from the symmetry of the alternate growth model as shown in Figure 5. The outer branch tips had more chance collecting molecules, so more fine structures (like fish scale) were found on the surface, and void was generated by shadowing effect. It should be emphasized that Figure 5 is a simplified 2D diagram, whereas the real branches will grow in a 3D space, which should lead to the complex 3D feather-like nanostructure. Nevertheless, a perfect explanation of the 3D feather-like AlN nanostructures still needs more detailed and direct evidences.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

A complex three-dimensional (3D) feather-like AlN nanostructure was synthesized by a direct reaction of high-purity Al granules with nitrogen using an arc discharge method. By adjusting the discharge time, a coral-like nanostructure, which evolved from the feather-like nanostructure, has also been observed. The novel 3D feather-like AlN nanostructure has a hierarchical dendritic structure, which means that the angle between the trunk stem and its branch is always about 30° in any part of the structure. The fine branches on the surface of the feather-like nanostructure have shown a uniform fish scale shape, which are about 100 nm long, 10 nm thick and several tens of nanometers in width. An alternate growth model has been proposed to explain the novel nanostructure. The spectrum of the feather-like products shows a strong blue emission band centered at 438 nm (2.84 eV), which indicates their potential application as blue light-emitting diodes.

No MeSH data available.