Nonaqueous synthesis of amorphous powder precursors for nanocrystalline PbTiO3, Pb(Zr,Ti)O3, and PbZrO3

A novel, facile nonaqueous synthesis route to nanocrystalline lead zirconate titanate (PZT) powders is presented. Simple mixing of lead acetylacetonate with titanium and/or zirconium alkoxides in 2-butanone, followed by a solvothermal treatment at 200 degrees C, produced amorphous, nanosized precursor powders. According to X-ray diffraction and transmission electron microscopy investigations, calcination at comparably low temperatures yielded highly crystalline, phase-pure powders consisting of monocrystalline particles in the size range of about 10-30 nm. Thermogravimetric and infrared analyses of the as prepared samples showed a content of organic species of about 10 wt %, which are decomposed between 200 and 330 degrees C. The lack of further weight loss above 400 degrees C proves the absence of PbO evaporation, a major drawback of previous PZT preparations. Crack-free thin films were obtained by simply casting a dispersion of precursor powders on a silicon substrate followed by thermal treatment. Scanning electron microscopy shows homogeneous films to some extent populated with regular, micrometer-sized spheres. However, thorough washing removed most of these larger objects to leave a plain film. According to atomic force microscopy measurements, the roughness of this film is in the nanometer-size regime, confirming that this route is a potential way to fabricate thin homogeneous piezoelectric films.