Ferroelectric Mesocrystalline BaTiO<sub>3</sub>/SrTiO<sub>3</sub> Nanocomposites with Enhanced Dielectric and Piezoelectric
Responses
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Abstract
A platelike mesocrystalline
BaTiO<sub>3</sub>/SrTiO<sub>3</sub> (BT/ST) nanocomposite is prepared
via a clever two-step solvothermal soft chemical process. First a
protonated titanate H<sub>1.07</sub>Ti<sub>1.73</sub>O<sub>4</sub>·<i>n</i>H<sub>2</sub>O (HT) crystal with a layered
structure and platelike morphology is solvothermally treated in a
Ba(OH)<sub>2</sub> solution to generate a homogeneous platelike BaTiO<sub>3</sub>/HT (BT/HT) nanocomposite. Second the generated BT/HT nanocomposite
is solvothermally treated in a Sr(OH)<sub>2</sub> solution to generate
the mesocrystalline BT/ST nanocomposite with platelike particle morphology.
The transformation reactions from the HT precursor to the mesocrystalline
BT/ST nanocomposite are topochemical conversion reactions, and the
formed BT/ST nanocomposite is constructed from well-aligned BT and
ST nanocrystals in the same crystal-axis orientation. The BT/ST nanocomposite
annealed at 900 °C shows a ferroelectric behavior and drastically
enhanced piezoelectric and dielectric responses owing to the introduction
of a lattice strain at a three-dimensional heteroepitaxial interface
between the BT and ST nanocrystals in the mesocrystal. The nanostructure
of the BT/ST mesocrystal is suitable for simultaneous application
of the strain engineering and the orientation engineering to develop
high performance piezoelectric and dielectric materials
