Temperature dependent local structure coherence of surface-modified BaTiO3 nanocubes

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 10; no. 30; pp. 10832 - 10842
• Main Authors: Jiang, Bo, Zhao, Changhao, Metz, Peter C, Palani Raja Jothi, Kavey, Benard, Reven, Linda, Lindner-D'Addario, Michael, Jones, Jacob L, Caruntu, Gabriel, Page, Katharine
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 04.08.2022
• Subjects: Barium titanates; Capping; Distribution functions; Ferroelectric materials; Ferroelectricity; Ligands; Nanocrystals; NMR; NMR spectroscopy; Nuclear magnetic resonance; Oleic acid; Phase transitions; Polymer matrix composites; Synchrotron radiation; Synchrotrons; Temperature dependence; Thin films; Titanium; Transition temperature
• DOI: 10.1039/d2tc00477a
• ISSN: 2050-7526

Surface functionalized barium titanate (BaTiO3) nanocrystals have been explored for highly tunable chemical and electronic properties, potentially of use in ceramic-polymer composites for flexible ferroelectric device applications, directed synthesis of ferroelectric thin films or other nano-architectures, and other potential applications. The detailed temperature dependent local structure evolution of BaTiO3 nanocubes capped with nonpolar oleic acid (OA) and polar tetrafluoroborate (BF4−) ligands are investigated using in situ synchrotron X-ray diffraction and pair distribution function (PDF) analysis, in conjunction with piezoresponse force microscopy (PFM) and 137Ba nuclear magnetic resonance (NMR) spectroscopy measurements. Diffraction analysis reveals that nanocubes capped by polar BF4− ligands undergo sharper ferroelectric to paraelectric phase transitions than nanocubes capped with nonpolar OA ligands, with the smallest ∼12 nm nanocubes displaying no transition. Local non-centrosymmetric symmetry is observed by PDF analysis and confirmed by NMR, persisting across the phase transition temperature. Local distortion analysis, manifested in tetragonality (c/a) and Ti off-centering (zTi) parameters, reveals distinct temperature and length-scale dependencies with particle size and capping group. Ferroelectric order is increased by polar BF4− ligands, which is corroborated by an enhancement of PFM response.