Effect of Acetylacetone on the Phase Formation of BST

The effect of additives acetylacetone and diethanolamine (DEA) and solvents 2-methoxyethanol and ethylene glycol on phase formation in BST was studied. While it was found difficult to detect the carbonate phase by x-ray diffraction, the FTIR spectra of some samples clearly showed a peak at ∼1440 cm⁻¹ corresponding to the carbonate phase. It was observed using FTIR that when acetylacetone is used as an additive, no intermediate carbonate (CO ₃ ²⁻ ) phase forms; in all the other cases an intermediate carbonate phase was found to form. Use of acetylacetone also lowered the crystallization temperature of BST. The modulating mechanism of acetylacetone on the phase formation of BST can be explained by considering the structure and mechanism of formation of BST gel. When acetylacetone is used as an additive to the sol, the hydrolysis and condensation reactions are slowed down and no segregation of different ions occurs. This avoids the formation of the intermediate carbonate phase.

† Present address for Aditi Datta: Department of Metallurgy, Indian Institute of Science, Bangalore 560012, India.

Keywords:

• BST
• sol-gel
• FTIR
• acetylacetone
• intermediate phase

Acknowledgments

Paper originally presented at AMF-4, Bangalore, India, December 12-15, 2003.

Notes

† Present address for Aditi Datta: Department of Metallurgy, Indian Institute of Science, Bangalore 560012, India.