SIZE-CONTROLLED SYNTHESIS OF NANOCRYSTALLINE BATIO3 BY A SOL-GEL TYPEHYDROLYSIS IN MICROEMULSION-PROVIDED NANOREACTORS

Using the hydrolysis of appropriate alkoxide mixtures in water-in-oil microemulsions, nanocrystalline BaTiO3 has been prepared in the form o f nonaggregated, cube-shaped crystals at room temperature without any sintering process as is demonstrated by means of x-ray diffractograms and transmission electron micrographs. By variation of the length of t he hydrophilic part of the surfactant molecules, the diameter of the w ater droplets in the microemulsions could be tuned to values between 8 and 55 nm as determined by dynamic Light scattering. The size of the resulting nano-BaTiO3 (6 nm less than or equal to [d](vol) less than o r equal to 17 nm) was evaluated from the line broadening of x-ray refl ections and correlates to the droplet size. The particle size distribu tion is very narrow, and in some cases nearly monodisperse.