Electronics

Easy phase transitions spur high piezoelectric responses

First-principles calculations reveal a flat energy landscape between the coexisting polymorphs in strained BiFeO3 thin films, which may lead to enhanced piezoelectric response.

A material’s atomic arrangement strongly influences its physical properties. This impact has long been known for metals, whicDixit_ADVS201500041h are usually atomically ordered as crystals. For example, white and gray tins differ only because their crystalline atomic arrangements vary. In complex oxides, applied electric fields can trigger structural changes as in the case of piezoelectrics. Most piezoelectrics, such as those used in sonar devices and actuators, rely on lead-containing materials. Growing concerns about the toxicity of lead has encouraged the scientific community seeking more environmentally benign alternatives.

Bismuth ferrite (BiFeO3), which is a ferroelectric material with a Curie temperature of 1100 K and rhombohedral symmetry is an appropriate choice. In their latest study, researchers from the Oak Ridge National Lab, Tennessee, USA, employed theory and experiment to study phase transitions in bismuth ferrite. Theoretical calculations, based on newly obtained experimental geometries, predict an almost barrierless transition between co-existing phases. This facile transition provides insight into the origin of the high electromechanical responses found in coexisting polymorphs in this Pb-free material. These results emphasize the importance of strain engineering for tuning electromechanical responses or, creating unique energy harvesting photonic structures, in oxide thin film architectures.

Read the whole research article now in the latest issue of Advanced Science.

Advanced Science is a new journal from the team behind Advanced MaterialsAdvanced Functional Materials, and Small. The journal is fully Open Access and is free to read now at www.advancedscience.com.

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