College of Engineering News • Iowa State University

Tan’s phase transition discovery published in Physical Review Letters

Xiaoli Tan

Associate Professor of Materials Science and Engineering Xiaoli Tan’s research to examine a phase boundary between antiferroelectric and ferroelectric ceramics was recently published in Physical Review Letters (PRL). The paper “Can an electric field induce an antiferroelectric phase out of a ferroelectric phase?” was included in the December 17 issue of PRL, which is the world’s foremost physics journal, providing rapid publication of short reports of significant fundamental research.

Tan, along with graduate students Joshua Frederick and Cheng Ma, and Wook Jo and Jürgen Rödel from Technische Universität Darmstadt in Germany, studied a ceramic system to explore the composition boundary between the material’s antiferroelectric and ferroelectric phases. An antiferroelectric crystal consists of an ordered array of electric dipoles with adjacent dipoles oriented in opposite directions, whereas a ferroelectric crystal’s dipoles all point in the same direction.

The researchers discovered that exposing a ceramic in the ferroelectric phase to a moderate electric field with a reversed polarity prompts the antiferroelectric phase. This transition of phases was previously considered unlikely because the electric field is widely believed to favor the ferroelectric phase over the antiferroelectric one as implied from the Coulomb’s Law.

Antiferroelectric and ferroelectric materials, capable of converting electrical signals into mechanical vibrations and vice versa, are widely used in sensors, capacitors, and communication devices. This discovery may lead to the production of new electric energy storage devices, which are urgently needed for electricity from clean and renewable sources, such as wind and solar. In addition, the principle of the phase transition can be extended to other materials with coupled subsystems, such as the giant magnetocaloric crystals with coupled magnetic and structural transitions.