Enhanced non-classical electrostriction in strained tetragonal ceria

• Published in: Nature communications Vol. 16; no. 1; pp. 36 - 11
• Main Authors: Santucci, Simone, Vasiljevic, Milica, Zhang, Haiwu, Tinti, Victor Buratto, Bergne, Achilles, Morin-Martinez, Armando A., Chaluvadi, Sandeep Kumar, Orgiani, Pasquale, Sanna, Simone, Lyksborg-Andersen, Anton, Hansen, Thomas Willum, Castelli, Ivano E., Pryds, Nini, Esposito, Vincenzo
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 02.01.2025; Nature Publishing Group; Nature Portfolio
• Subjects: 140/146; 147/143; 147/28; 639/301/1005/1006; 639/301/357; 639/925/357; Cerium oxides; Compressive properties; Crystal defects; Crystal growth; Crystal lattices; Dipoles; Elastic analysis; Elastic anisotropy; Electric fields; Electrostriction; Epitaxial growth; Gadolinium; Humanities and Social Sciences; Induced polarization; Lattice strain; Metal oxides; multidisciplinary; Polarization; Science; Science (multidisciplinary); Single crystals; Strain analysis; Structural analysis; Tensile strain; Thin films
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-55393-6

Electrostriction is the upsurge of strain under an electric field in any dielectric material. Oxygen-defective metal oxides, such as acceptor-doped ceria, exhibit high electrostriction 10 -17 m 2 V -2 values, which can be further enhanced via interface engineering at the nanoscale. This effect in ceria is “non-classical” as it arises from an intricate relation between defect-induced polarisation and local elastic distortion in the lattice. Here, we investigate the impact of mismatch strain when epitaxial Gd-doped CeO 2 thin films are grown on various single-crystal substrates. We demonstrate that varying the compressive and tensile strain can fine-tune the electromechanical response. The electrostriction coefficients achieve a large M 11  ≈ 3.6·10 -15 m 2 V -2 in lattices of in-plane compressed films, i.e., a positive tetragonality ( c/a -1 > 0), with stress above 3 GPa at the film/substrate interface. Chemical and structural analysis suggests that the high electrostriction stems from anisotropic distortions in the local lattice strain, which lead to constructively oriented elastic dipoles and Ce 3+ electronic defects. Non-classical electrostriction in fluorites arises from defect-induced polarization and lattice distortions. This study shows that mismatch strain in Gd-doped CeO 2 thin films fine-tunes electromechanical responses, achieving high electrostriction above 10− 15 m 2 V −2 .