High temperature phase transformation and the mechanism in YTaO4

4^th International Conference and Exhibition on Materials Science & Engineering

September 14-16, 2015 Orlando, USA

Jing Feng1, 2

1Kunming University of Science and Technology, People�s Republic of China 2Harvard University, USA

ScientificTracks Abstracts-Workshop: J Material Sci Eng

Abstract :

High temperature phase transformation and the mechanism in YTaO4 ceramics as potential thermal barrier coatings material is investigated by experiments and first principles calculation. High temperature in situ XRD and Raman were indentified the phase transformation of yttrium tantalate. HRTEM showed the microstructure of phase transformation between monoclinic phase and tetragonal phase. The mechanism of phase transformation was discussed by the first principles canlualtion combined the Landau free energy expansion. Calculations of Gibbs free energies show that the phase transformation temperature at 1430oC, close to the experimental value of 1426�±7oC. Landau free energy expansions demonstrate that the transition is second order and, based on the fitting to experimental and calculated lattice parameters, it is found that the transition is a proper rather than a pseudoproper type. Together, these finding are consistent with the transition being ferroelastic.

Biography :

Jing Feng has completed his PhD in Materials Scienece from Kunming University of Science and Technolgy & Tsinghua University in China. He is a Postdoc Fellow and Research Associate in Harvard University at 2012-2015. He is the Director of Lab of Advanced Materials in Designing and Application of Kunming University of Science and Technolgy. He has published more than 100 papers in reputed journals and has been cited more than 1000 times.

Email: fengj09@mails.tsinghua.edu.cn