Materials Frontier No.141
Title: Thermal Expansion Anomaly Regulated by Entropy
Speaker: Prof. Zi-Kui Liu, Department of Materials Science and Engineering, The PennsylvaniaStateUniversity
Venue: Yao Zheng Hall (formerly 500),MaterialBuildingA
Inviter: Prof Xuejun JIN
Zi-Kui Liu is a professor in Materials Science and Engineering atPennsylvaniaStateUniversity. He received his Ph.D. degree in Royal Institute of Technology inSwedenin 1992. He worked at the Royal Institute of Technology inSweden, University of Wisconsin-Madison, Questek Innovation in theUSA. He was employed as the Lecture Professor of Changjiang Scholarship of Ministry of Education at Central South University in China, working with Professor Yong Du. He is the Editor-in-Chief of the international journal of CALPHAD. He published 318 high level papers in peer-reviewed journals including Nature Materials and Physical Review Letters. He was also granted more than 30 projects from federal agencies such as NSF, NSFC, DOE and NASA. He received NSF Career Award, TMS Brimacombe Medalist Award, ASM International Materials Science Research Silver Award, ASM Fellow, ASM J. Willard Gibbs Phase Equilibria Award, and ACers Spriggs Phase Equilibria Award due to his outstanding contribution to materials research.
Thermal expansion of matter is defined by volume change with respect to temperature under constant pressure. Through the thermodynamic relation between thermal expansion and entropy, we show that the thermal expansion can be predicted through multi-scale modeling of entropy. We demonstrate that a macroscopically homogeneous single phase can have its entropy significantly altered by metastable microstates when the energy difference between stable and metastable microstates is changed by temperature or pressure, resulting in abnormal behavior of the thermal expansion of the system such as colossal, zero, or negative thermal expansion [1,2]. Some examples include Fe3PT as an Invar material, cerium as an anti-invar materials, and water/ice with unique thermal expansion behaviors. We believe that this entropy contribution due to metastable microstates, termed microstate configurational entropy (MCE), is also responsible for other anomalies in materials due to unique properties of microstates and non-linear dynamic interactions among them.
1. Y. Wang, S. L. Shang, H. Zhang, L. Q. Chen and Z. K. Liu, "Thermodynamic fluctuations in magnetic states: Fe3Pt as a prototype," Phil. Mag. Lett., Vol.90, 2010, 851-859.
2. Z. K. Liu, Y. Wang and S. L. Shang, "Origin of negative thermal expansion phenomenon in solids," Scr. Mater., Vol.65, 2011, 664-667.