鉛を含まない新しい圧電体材料を開発(Scientists create new lead-free piezoelectric materials)

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2022-03-14 スイス連邦工科大学ローザンヌ校(EPFL)

EPFLの研究者たちは、研究室で合成したガドリニウム添加酸化セリウムが、ある種の圧電材料に代わる有望な材料となる可能性を発見しました。また、最高の圧電材料とは異なり、鉛を含まないため、生体適合性のある医療用途に使用できる可能性がある。

鉛を含まない新しい圧電体材料を開発(Scientists create new lead-free piezoelectric materials)© Alain Herzog 2022 EPFL

<関連情報>

中心対称性酸化物における誘起巨大圧電特性 Induced giant piezoelectricity in centrosymmetric oxides

A surprising way to detect strain

Piezoelectric materials usually rely on their crystal structure alone to create electrical charge in response to strain. This makes the materials attractive for a variety of sensing applications. Park et al. present a different strategy by introducing gadolinium into non-piezoelectric cerium dioxide (see the Perspective by Li). This approach also creates oxygen vacancies that turn the material into one with a frequency-dependent piezoelectric effect under a static electric field. The size of the effect is similar to that of commercial piezoelectric materials, and the strategy should work more generally for a wide class of materials. —BG

Abstract

Piezoelectrics are materials that linearly deform in response to an applied electric field. As a fundamental prerequisite, piezoelectric materials must have a noncentrosymmetric crystal structure. For more than a century, this has remained a major obstacle for finding piezoelectric materials. We circumvented this limitation by breaking the crystallographic symmetry and inducing large and sustainable piezoelectric effects in centrosymmetric materials by the electric field–induced rearrangement of oxygen vacancies. Our results show the generation of extraordinarily large piezoelectric responses [with piezoelectric strain coefficients (d33) of ~200,000 picometers per volt at millihertz frequencies] in cubic fluorite gadolinium-doped CeO2−x films, which are two orders of magnitude larger than the responses observed in the presently best-known lead-based piezoelectric relaxor–ferroelectric oxide at kilohertz frequencies. These findings provide opportunities to design piezoelectric materials from environmentally friendly centrosymmetric ones.

 

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