Size–Temperature Phase Diagram of Titanium Nanosolids

• Published in: Journal of physical chemistry. C Vol. 116; no. 1; pp. 237 - 241
• Main Authors: Xiong, Shiyun, Qi, Weihong, Huang, Baiyun, Wang, Mingpu, Li, Zhou, Liang, Shuquan
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 12.01.2012
• Subjects: C: Nanops and Nanostructures; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Materials science; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase diagrams of metals and alloys; Physics; Quantum wires; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Nanoparticles; Temperature dependence; Phase diagrams; Gibbs free energy; Experimental result; Transition temperature; Size effect; Titanium; Nanowires; Nanostructured materials; Optimization
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp208149d

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., P n = P b(1 – K/D), where P b 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.