Journal of Materials Research

Articles

Crystallization and high-temperature structural stability of titanium oxide nanotube arrays

Oomman K. Varghesea1, Dawei Gonga2, Maggie Paulosea2, Craig A. Grimesa2 and Elizabeth C. Dickeya3 c1

a1 Department of Materials Science & Engineering and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802

a2 Department of Electrical Engineering & Materials Research Institute, 217 Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802

a3 Department of Materials Science & Engineering and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802

Abstract

The stability of titanium oxide nanotube arrays at elevated temperatures was studied in dry oxygen as well as dry and humid argon environments. The tubes crystallized in the anatase phase at a temperature of about 280 °C irrespective of the ambient. Anatase crystallites formed inside the tube walls and transformed completely to rutile at about 620 °C in dry environments and 570 °C in humid argon. No discernible changes in the dimensions of the tubes were found when the heat treatment was performed in oxygen. However, variations of 10% and 20% in average inner diameter and wall thickness, respectively, were observed when annealing in a dry argon atmosphere at 580 °C for 3 h. Pore shrinkage was even more pronounced in humid argon environments. In all cases the nanotube architecture was found to be stable up to approximately 580 °C, above which oxidation and grain growth in the titanium support disrupted the overlying nanotube array.

(Received August 20 2002)

(Accepted October 17 2002)

Correspondence:

c1 Address all correspondence to this author. e-mail: ecdlo@psu.edu

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