1364
G.W. Yan et al. / Materials Research Bulletin 44 (2009) 1360–1365
Fig. 8. SEM images of samples obtained upon addition of different amounts of Na2S solution. The volume of Na2S solution added is: (a and b) 0.5 mL; (c and d) 1.5 mL; (e and f)
2.5 mL.
engaged replacement reaction [30]. In a very recent report, quadrate
Cu(TCNQ) (TCNQ = 7,7,8,8-tertracyno-p-quinodimethane) micro-
tubes were obtained through a dissolution process preferentially
occurring in the center of rod-like crystal and deepening gradually
into the depth of the crystal [31]. A similar phenomenon was
observed in ZnO crystalline microtubes reported by Vayssieres et al.
[32]. The center of the ZnO microtubes dissolved preferentially
owing to an unsatisfactory crystallinity.
explain the formation of quadrate CuS submicrotubes. The XRD
measurement showed that CuS submicrotubes were constructed
by covellite CuS with a hexagonal phase. This facile method may be
applied to synthesize other inorganic materials with hollow
structure.
Acknowledgments
In our case, the intermediate process has not been monitored
due to the rapid reaction. Instead, the formation process of CuS
submicrotube was investigated by addition of different amounts
of Na2S solution, while Cu(Tu)Clꢀ0.5H2O was kept excess in the
system. Fig. 8 shows SEM images of samples collected after
addition of 0.5 mL, 1.5 mL and 2.5 mL of Na2S solution,
respectively. When 0.5 mL of Na2S solution is added, besides
the initial solid rods, some rods show small craterlets on their
ends (Fig. 8(a) and (b)), and their surfaces become rough. It is
found that the craterlets become bigger and deeper, ultimately
resulting in the formation of tubular structure, see Fig. 8(c) and
(d), and (e) and (f), where 1.5 mL and 2.5 mL Na2S solution are
added, respectively. These results suggest that quadrate CuS
submicrotubes are formed through the template-engaged
replacement reaction, and the differential diffusion rates of
reactants facilitate the fabrication of hollow structure. However,
the detailed mechanism for the formation of quadrate CuS
submicrotubes is not fully understood and requires more sys-
tematic and extensive study.
This work was supported by the Natural Science Foundation of
China (No. 20771092), Zhejiang Provincial Natural Science
Foundation of China (No. Y406295) and PCSIRT (No. 0654).
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