Classical to Relaxor Ferroelectric Transformation of Lanthanum Modified BaTi_0.91Sn_0.09O₃ Ceramics

Abstract

Lead-free Ba_1-xLa_xTi_0.91Sn_0.09O₃ (BLTS) ceramics with x = 0, 0.01, 0.03 and 0.05, were prepared by the traditional solid-state sintering method with calcination and sintering temperatures of 1200 °C for 2 h and 1400 °C for 4 h, respectively. X-ray diffraction (XRD) measurements revealed that all the BLTS ceramics had pure perovskite structures with no detectable impurities. When x = 0 and 0.01, the ceramics exhibited coexisting orthorhombic (O) and tetragonal (T) phases, while the orthorhombic (O), tetragonal (T) and cubic phase (C) were detected in the BLTS ceramics with x = 0.03 and 0.05, which the Rietveld refinement analysis confirmed. Furthermore, increasing x in the BLTS ceramics led to a large decrease in the average grain size (from 45.7 to 0.9 µm). A significant decrease in the remnant polarization (P_r) accompanied by very slim hysteresis loops were observed for higher La (x ≥ 0.03) levels. This demonstrates that BLTS ceramics transition from classical ferroelectric to relaxor ferroelectric behavior due to changing occupancy of the A-site to La³⁺ from Ba²⁺.

Keywords:

• phase formation
• microstructure
• Rietveld refinement
• hysteresis loop
• relaxor ferroelectric

Acknowledgments

The authors wish to thank the Department of Physics, Faculty of Science, Naresuan University for their supporting facilities. Thank are also given to Asst. Prof. Dr. Kyle V. Lopin for his help in editing the manuscript.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by The National Science, Research and Innovation Fund (NSRF) through Naresuan University (R2565B059).