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 (Ba0.7Sr0.3TiO3) powder in the range of 15 - 25 run using a simple sol-gel processing route. Barium acetate, strontium acetate and titanium isopropoxide were used as precursors. By varying the pH of the sol 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 BaojSrojTiOj gel obtained was dried at 200°C, to form powder and subsequently calcined in the temperature range of 400°C to 700°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°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 Ba0.7Sr0.3TiO3 powder obtained after calcination at 700°C was in the range 15-25 run.