Enhanced dielectric properties of Nanocrystalline Ba(1-x)SrxTiO3 (x=0 and 0.3) ceramics

Abstract

In this paper, we report the enhancement of the dielectric constant of barium titanate (BTO) through partial substitution of strontium to barium and crystallite size reduction through a high power ultrasonic treatment. The sample under investigation is Ba1-xSrxTiO3 or BST with x = 0 and 0.3 compositions prepared through mechanical alloying of SrCO3, BaCO3 and TiO2 precursors as the feedstock. All mechanically alloyed samples were crystalline powders with a single phase as confirmed by an x-ray diffractometer (XRD). The mechanically alloyed materials were consisted of multi-crystallite particles as confirmed both by XRD data analysis and particle size evaluation. Subject to an additional ultrasonic treatment, the multi-crystallite particles were fragmented toward mono-crystallite particles with the mean crystallite size about 52 nm after 12 hours irradiation. Even a smaller mean crystallite size (18 nm) with a narrower crystallites distribution then that of BTO was obtained in Ba1-xSrxTiO3 with x = 0.3. Such a narrow crystallite size distribution with a small mean crystallite size has superior dielectric constant over those of BTO and doped BTO with a large mean crystallite size. The highest dielectric constant of 3000 was obtained at a frequency of 273 Hz in doped BTO after 12 hours ultrasonic irradiation. The value is 12 times higher than those of BTO and doped BTO with a large crystallite size.