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Size–Temperature Phase Diagram of Titanium Nanosolids

2011; American Chemical Society; Volume: 116; Issue: 1 Linguagem: Inglês

10.1021/jp208149d

1932-7455

Shiyun Xiong, Weihong Qi, Baiyun Huang, Mingpu Wang, Li Zhou, Shuquan Liang,

Advanced Thermoelectric Materials and Devices

The size and temperature dependent Gibbs free energies of titanium nanosolids (nanoparticles, nanowires, and nanofilms) are calculated through the optimization of our previous Gibbs free energy model, and then the size–temperature phase diagrams of titanium nanosolids have been obtained. It is found that Gibbs free energy of titanium nanosolids reveals a strong size effect in small size ranges, and it increases with the decrease of size and temperature. The size dependent Gibbs free energy and structure transition temperature of titanium nanosolids can be expressed by the universal relationship accurately, i.e., Pn = Pb(1 – K/D), where Pb denotes the corresponding bulk properties, and K is the material constant. The calculated results indicating the variation ratio among nanoparticles, nanowires, and nanofilms satisfies 3:2:1. Significantly, besides the HCP to FCC and HCP to BCC transitions, we predict an unobserved structure transition between FCC and BCC structures in the size and temperature ranges between 8.1 nm and 1715 K to 27.3 nm and 1156 K for nanoparticles, 5.5 nm and 1705 K to 18.6 nm and 1152 K for nanowires, and 2.7 nm and 1701 K to 9.2 nm and 1150 K for nanofilms. The present calculations agree well with experimental results.