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MATERIALS RESEARCH

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Synthesis of PbTiO3/organic hybrid from metalorganic compounds Toshinobu Yogo, Hiroyuki Ukai, Wataru Sakamoto, and Shin-ichi Hirano Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan (Received 18 June 1998; accepted 23 April 1999)

A nanocrystalline PbTiO3 particle/organic hybrid was synthesized through hydrolysis and polymerization of metalorganic compounds below 100 °C. The PbTiO3 precursor was synthesized from lead methacrylate and titanium isopropoxide. The formation of a Pb–Ti complex alkoxide was confirmed by H and Pb nuclear magnetic resonance spectroscopy. Hydrolyzed Pb–Ti alkoxide was polymerized, yielding the PbTiO3 particles/oligomer hybrid. The organic matrix included nano-sized crystalline particles, depending on the hydrolysis conditions. The nanocrystalline particles were identified to be lead titanate by electron diffraction and energy-dispersive x-ray analysis. The dielectric constant of the nanometer-sized PbTiO3/oligomer hybrid was 5.2 at 10 kHz.

I. INTRODUCTION

Inorganic/organic hybrid materials attract special attention because they are expected to have new properties and the combined beneficial properties of each material.1–3 Hybrid materials consist of nanostructures, including various types of organic and inorganic phases, such as molecules, layers, and particles.4 The chemical design of the molecular precursors and the synthesis conditions are the key for synthesis of these materials. The mixing of small particles with a polymer is quite difficult because particles agglomerate as a result of van der Waals force. Hence, the generation of dielectric or magnetic particles in situ in a polymer matrix could be highly advantageous over conventional mixing of dielectric or magnetic particles with a polymer. We synthesized nanocrystalline BaTiO3/organic hybrids from a modified titanium and barium alkoxide under controlled hydrolysis conditions below 100 °C.5,6 Iron oxide particle/ organic hybrids were successfully synthesized by means of a designed metalorganic compound precursor that exhibited the interesting feature.7 PbTiO3 has a perovskite structure and is one of the ferroelectric materials with attractive ferroelectric and pyroelectric properties. Crystalline PbTiO3 particles were reported to be formed from lead acetate and titanium alkoxide after heat treatment at 470 °C.8 Usually, heat treatment above 400 °C is required to form the crystalline phase of PbTiO3 precipitated from titanium tetrachloride and lead nitrate.9 To control the homogeneous nucleation and growth of complex oxide particles in organic polymer matrices, the starting metalorganic compounds that include the desired elements are required to dissolve in organic solvents. The uniform formation of a J. Mater. Res., Vol. 14, No. 8, Aug 1999

nanocrystalline perovskite phase results from the controlled nucleation and growth, which is attributed to the reactivity of double metalorganic compounds. This article