Effect of Partial Replacement of Bi on Electrical Properties of Layer Structured Strontium Bismuth Titanate

Bismuth in SrBi ₄ Ti ₄ O ₁₅ is partially replaced with La ^{3 +} to synthesize SrBi_{(4 − X)}La _X Ti ₄ O ₁₅ , with x = 0.25,0.5,0.75. The samples have been prepared by sol-gel method using ethylene glycol gel and aqueous solution. This sol-gel process offers some advantages, such as homogeneity and stoichiometry control. The structural characterization of the samples is done using powder X-ray diffraction measurements. The samples are electrically characterized by using dielectric and impedance spectroscopy measurements in the frequency range of 500 Hz to 1 MHz, and temperature range from RT to 600°C. These samples show strong frequency and temperature dependent dielectric relaxations. The power law dependence on a.c conductivity is evaluated. The effect of La ^{3 +} substitution on dielectric, impedance and a.c conductivity is studied. The results obtained are interpreted in terms of the pluckering and on the consequent lattice distortion that is usually present in Bismuth Layer Structured Ferroelectrics.

Keywords:

• BLSF material
• SrBi₄Ti₄O₁₅
• dielectric constant
• La-doped
• electrical conductivity

Acknowledgments

We thank DRDO, New Delhi, India for the financial support. One of the authors (MR) thanks Prof. S.V. Suryanarayana and Prof. T. Bhima Sankaram for their encouragement.

Paper originally presented at AMF-4, Banglore, India, December 12–15, 2003