SYNTHESIS AND CHARACTERIZATION OF NANOCRYSTALLINE BARIUM STRONTIUM TITANATE CERAMICS

Nano-grained Barium Titanate based ceramics are of interest, for applications in ultra thin dielectric layers. In this work, we have synthesized nanocrystalline Barium Strontium Titanate (Ba(0.7)Sr(0.3)TiO(3)) powder in the range of 15 - 25 nm using a simple sol-gel processing route. Barium acetate, strontium acetate and titanium isopropoxide were used as precursors. By varying the pH of the sot and the calcination temperature a simple sol-gel synthesis was developed which can be easily repeated. Thermal properties of the processed gel were determined using Differential Scanning Calorimetry and Thermogravimetric analysis. The Ba(0.7)Sr(0.3)TiO(3) gel obtained was dried at 200 degrees C, to form powder and subsequently calcined in the temperature range of 400 degrees C to 700 degrees C for crystallization. X-Ray Diffraction technique was used to study the phase evolution and phase purity during synthesis. Crystallite size of the powder was also determined using X-ray diffraction patterns. XRD patterns showed variation in phase evolution as a function of pH of the solution. Scanning Electron Microcopy of the synthesized powder calcined at 700 degrees C showed that the powder was in agglomerates, which were consisted of very fine particles. High Resolution Transmission Electron Microscopy (HR-TEM) results showed that the particle size of the Ba(0.7)Sr(0.3)TiO(3) powder obtained alter calcination at 700 degrees C was in the range 15-25 am.