• Ohki, Yoshimichi
• Takeuchi, Kazuo
• Sakabe, Yukio
• Suzuki, Keigo
• Fujita, Junya
• Wada, Nobuyuki

Abstract

<jats:p>To study the minimum particle size for a ferroelectric material at which ferroelectricity is retained, thin films composed of stoichiometric BaTiO<jats:sub>3</jats:sub> nanoparticles were prepared by laser ablation of a Ba–Ti–O ceramic target using a differential mobility analyzer. Highly densified films of various uniform grain sizes were obtained after post-annealing at 600, 700, 800, and 900 °C in an oxygen atmosphere. The dielectric constants of the post-annealed films varied from 100 to 300, depending on the grain size from 65 to 136 nm. These values are comparable to those of BaTiO<jats:sub>3</jats:sub> nano-granular films fabricated by metallorganic decomposition or the sol-crystal method. From the capacitance vs bias-voltage relationship and its hysteresis observed for the post-annealed films, it became clear that a phase transformation from paraelectric to ferroelectric occurs at a grain size of approximately 76 nm. It was also clarified from piezoresponse images of the post-annealed films obtained using a scanning probe microscope that ferroelectricity emerges in BaTiO<jats:sub>3</jats:sub> nano-size grains at a grain size of approximately 55 nm.</jats:p>

Topics

• nanoparticle
• impedance spectroscopy
• grain
• grain size
• phase
• mobility
• thin film
• Oxygen
• dielectric constant
• annealing
• ceramic
• decomposition
• laser ablation