Conformal coating of ferroelectric oxides on carbon nanotubes

¹ Institute for Functional Nanomaterials, University of Puerto Rico - P.O. Box 23343, San Juan, PR 00931, USA
² Department of Physics, University of Puerto Rico - P.O. Box 70377, San Juan, PR 00936, USA
³ Department of Earth Science, University of Cambridge - Cambridge CB2 1PZ, UK, EU
⁴ Department of Chemistry, University of Puerto Rico - P.O. Box 70377, San Juan, PR 00936, USA

^a ashok553@gmail.com
^b gerardo.morell@upr.edu

Received: 8 July 2011
Accepted: 28 November 2011

Abstract

Nano-size barium strontium titanate Ba_0.7Sr_0.3TiO₃ (BST) maize-bead–like structures were conformally coated on bamboo-like carbon nanotubes (BCNTs) grown on copper substrates. Initially BCNTs were fabricated by hot-filament chemical vapor deposition (HF-CVD) techniques on Cu substrates. Later, BST was deposited on BCNT/Cu by pulsed laser deposition (PLD) techniques. Surface morphology, cross-sectional image and topography of the BCNTs and BCNT-BST maize-like nanostructures were investigated by X-ray, field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy and tunneling electron microscopy (TEM) techniques. BST-BCNT hybrid structures provide an additional degree of freedom to interconnect the oxides, which in turn provides [3D] geometry for functionality. There had been a popular misconception that oxides cannot grow on CNT at high temperature; this long-standing problem has now been solved. The present unregistered nanostructures can be used as sensors; however, if these structures are made as registered arrays, they can be used as nonvolatile memory elements and high-energy density capacitors.