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Journal of Nanomaterials
Volume 2014, Article ID 309827, 5 pages
http://dx.doi.org/10.1155/2014/309827
Research Article

Young’s Modulus of Polycrystalline Titania Microspheres Determined by In Situ Nanoindentation and Finite Element Modeling

1College of Mechanical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
2Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100022, China

Received 9 October 2014; Accepted 27 November 2014; Published 15 December 2014

Academic Editor: Sheng-Rui Jian

Copyright © 2014 Peida Hao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In situ nanoindentation was employed to probe the mechanical properties of individual polycrystalline titania (TiO2) microspheres. The force-displacement curves captured by a hybrid scanning electron microscope/scanning probe microscope (SEM/SPM) system were analyzed based on Hertz’s theory of contact mechanics. However, the deformation mechanisms of the nano/microspheres in the nanoindentation tests are not very clear. Finite element simulation was employed to investigate the deformation of spheres at the nanoscale under the pressure of an AFM tip. Then a revised method for the calculation of Young’s modulus of the microspheres was presented based on the deformation mechanisms of the spheres and Hertz’s theory. Meanwhile, a new force-displacement curve was reproduced by finite element simulation with the new calculation, and it was compared with the curve obtained by the nanoindentation experiment. The results of the comparison show that utilization of this revised model produces more accurate results. The calculated results showed that Young’s modulus of a polycrystalline TiO2 microsphere was approximately 30% larger than that of the bulk counterpart.