Abstract
A capillary-enforced template-based method has been applied to fabricate calcium copper titanate (CaCu3Ti4O12, CCTO) nanotubes (diameter ~200 nm) by filling sol-gel CCTO precursor solution into the nanochannels of porous anodic aluminum oxide (AAO) templates, subsequent heating for phase formation and fi- nally the removal of nano-channel templates by applying basic solution. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) equipped with Energy-dispersive X-ray spectroscopy (EDX) have been employed to characterize the morphology, structure, and composition of as-prepared nanotubes. XRD and selected-area electron diffraction (SAED) in-vestigations demonstrated that postannealed (750○C for 1 h) CCTO nanotubes were poly-crystalline with a cubic pseudo-perovskite cry- stal structure. The FE-SEM and TEM results showed that CCTO nanotubes were of uniform diameter (~200 nm) throughout their length. High resolution TEM (HRTEM) analysis confirm- ed that the obtained CCTO nanotubes are made of randomly aligned nano-particles 5-10 nm in size. EDX analysis demonstrated that stoichi- ometric CaCu3Ti4O12 was formed. The possible formation mechanism of CCTO nanotubes in the AAO template is discussed.
Highlights
Subsequent to the discovery of carbon nanotubes [1] by Iijima et al many research groups around the globe have become involved in the development of one-dimensional nano-structures such as nano-tubes, nano-rods, nanowires etc. of various functional materials due to their important role in mesoscopic physics and nanoscale device fabrication, as they can be utilized as both nanoscale device elements and interconnections while retaining unique properties due to size confinement in the radial direction [2,3,4,5,6]
In this article we are reporting the synthesis of gaint dielectric CCTO nanotubes of about 200 nm diameter by means of a sol-gel method utilizing nano-porous anodic aluminum oxide (AAO) templates, structural characterization of the nano-tubes and high resolution electron microscopic (HRTEM) studies on the nano-tube walls to reveal the crystalline structures
Since the size and uniformity of the product nanotubes solely depend on the used nanoporous AAO template, its features namely the uniformity of size of the pores in the template were studied by scanning electron microscope (SEM)
Summary
Subsequent to the discovery of carbon nanotubes [1] by Iijima et al many research groups around the globe have become involved in the development of one-dimensional nano-structures such as nano-tubes, nano-rods, nanowires etc. of various functional materials due to their important role in mesoscopic physics and nanoscale device fabrication, as they can be utilized as both nanoscale device elements and interconnections while retaining unique properties due to size confinement in the radial direction [2,3,4,5,6]. Nanotubes of various materials have been synthesized through various methods, among which sol-gel template technology provides a versatile technique for synthesizing highly ordered and controlled with the same structure and properties at large-scale production of one dimensional nanostructures, which is the basic building block of nanodevices. To a surprise the material is non-ferroic and shows a centrosymmetric structure down to 35 K [16] Both intrinsic and extrinsic mechanisms were employed to explain this unusual phenomenon. In this article we are reporting the synthesis of gaint dielectric CCTO nanotubes of about 200 nm diameter by means of a sol-gel method utilizing nano-porous anodic aluminum oxide (AAO) templates, structural characterization of the nano-tubes and high resolution electron microscopic (HRTEM) studies on the nano-tube walls to reveal the crystalline structures
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