(Phys.org)—The piezoelectric effect, which causes a material to expand along the direction of an applied electric field, is common in many materials and used in a variety of technologies, from medical ultrasound to vibration-powered electronics. But the negative piezoelectric effect, in which a material contracts rather than expands in the direction of the applied electric field, has been considered a rare and counterintuitive anomaly, and has received little attention.
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