Listening to Materials at the Nanoscale
The detection of local phase transitions remains challenging, and to date most techniques can detect properties that change at macroscopicscales or at atomic scales, but virtually no technique offers the ability to monitor and map bias-induced phase transitions at nanometer lengths. The detection of phase transitions at these length scales is crucial for understanding the function of a variety of materials used in energy transduction, harvesting, and piezoelectric actuation. Here, a non-destructive technique is demonstrated using an atomic force microscope tip, which is used to confine an electric field in a small (nanometers) volume of material. By using a special AC waveform applied to the tip, it is possible to ‘listen’ to the changes in the elastic properties of the material by monitoring the resonant frequency of the tip-sample contact. The technique is applied to a material used in ultrasound transducers and energy harvesting devices to detect and map a voltage-induced phase transition across the surface, and is compared to thermodynamic modeling, providing fresh insight into how these materials function at the relevant length scale.
R. K. Vasudevan, H. Khassaf, Y. Cao, S. Zhang, A. Tselev, B. Carmichael, M. B. Okatan, S. Jesse, L.-Q. Chen, P. Alpay, S. V. Kalinin, and N. Bassiri-Gharb, “Acoustic Detection of Phase Transitions at the Nanoscale,” Adv. Funct. Mater. 26, 478 (2016). DOI: 10.1002/adfm.201504407
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