Effect of La₂O₃ Doping on Phase Formation, Microstructure and Electrical Properties of (K_0.44Na_0.52Li_0.04)(Nb_0.84Ta_0.10Sb_0.06)O₃ Ceramics Synthesized via the Solid-State Combustion Method

Abstract

In this work, the effect of La₂O₃ doping (x = 0–1.6 wt%) on the phase formation, microstructure and electrical properties of (K_0.44Na_0.52Li_0.04)(Nb_0.84Ta_0.10Sb_0.06)O₃ (KNLNTS) ceramics was investigated. These samples were fabricated by the solid-state combustion method using glycine as fuel. The KNLNTS ceramics doping with La₂O₃ powders were calcined and sintered at 750 °C and between 1100 and 1200 °C, respectively, for 2 h. From the X-ray diffraction (XRD) results, the ceramics had a pure perovskite phase with coexisting orthorhombic and tetragonal phases in all samples. The Rietveld refinement analysis suggested that the tetragonality increased with increasing La₂O₃ doping. The grain morphology of the ceramics exhibited a rather square shape. The average grain size and the density of the ceramics tended to decrease from 1.5 to 0.7 µm and 4.71 to 4.56 g/cm³, respectively, when increasing La₂O₃ contents from 0 to 1.6 wt%. The dielectric behavior of the ceramics degenerated with La₂O₃ doping. A decrease in the leakage current and saturated hysteresis loops were observed in the samples doped with La₂O₃ ≥ 0.8 wt%.

Keywords:

• Phase formation
• microstructure
• Rietveld refinement
• dielectric properties
• solid state combustion method

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.

Additional information

Funding

This work was financially supported by the National Science, Research and Innovation Fund (NSRF) through Naresuan University (R2564B001).