Ca-3(VO4)(2) Nanowires on Metallic CaVO3 Films as Nanocapacitors

Valérie Demange (1, 2) , Bruno Berini (3) , Brice Gautier (4) , Elena Popova (3) , Yves Dumont (3) , Arnaud Fouchet (5)

1 ScanMAT - Synthèse Caractérisation Analyse de la Matière
2 ISCR - Institut des Sciences Chimiques de Rennes
3 GEMAC - Groupe d'Etude de la Matière Condensée
4 INL - Institut des Nanotechnologies de Lyon
5 CRISMAT - Laboratoire de cristallographie et sciences des matériaux

As Ca-3(VO4)(2) is known to be ferroelectric in bulk form at room temperature, we have investigated this material at the nanoscale and at different crystallographic orientations. In this context, self-organized Ca-3(VO4)(2) nanostructures have been grown on top of conducting complex oxide CaVO3 (CVO) thin films deposited by pulsed laser deposition on SrTiO3 (STO) substrates presenting three crystallographic orientations (i.e., (100)STO, (110)STO, and (111)STO). The growth of Ca-3(VO4)(2) nanostructures occurs at high temperature and is related to the oxidation of the CVO phase. Because the nanostructures exhibit epitaxial relationships with the CVO matrix, depending on the substrate orientation, we show that particular morphologies of nanostructures could be obtained with defined shape and orientation. Atomic force microscopy, transmission electron microscopy, and electron diffraction experiments were performed to characterize the different epitaxial relationships, and electron energy loss spectroscopy measurements confirm the oxidation transformation of the vanadium nanostructure (V5+) from the CVO film (V4+). Finally, piezoforce microscopy of the different nanostructures shows a nonzero piezoresponse, with in particular a clear piezoelectric activity for one type of orientation (i.e., [554]Ca-3(VO4)(2)) on (110)STO). In addition to the study of Ca-3(VO4)(2)2 nanostructures, a complete investigation of the different domains of orthorhombic CVO film has been conducted for the three orientations. This oxidation process is particularly innovative and can lead to a way of synthesis of nanocapacitors in a single-step process.

Mots clés: CaVO3; TEM; PFM; Complex oxide; Orthovanadate; Epitaxy; Nanorods; CaVO 3; Nanostructures; Thin films; Lattices; Physical and chemical processes

Domaines: Chimie

Valérie Demange, Bruno Berini, Brice Gautier, Elena Popova, Yves Dumont, et al.. Ca-3(VO4)(2) Nanowires on Metallic CaVO3 Films as Nanocapacitors. ACS Applied Nano Materials, 2020, 3 (7), pp.6684-6692. ⟨10.1021/acsanm.0c01136⟩. ⟨hal-02928615⟩