The influences of Cs⁺ substitution and direct doping on the phase evolution, microstructure and electrical properties of KNNT ceramics

Abstract

The effects of Cs⁺ substitution and direct doping in (K_0.5Na_0.5)(Nb_0.7Ta_0.3)O₃ (KNNT) ceramics, on the crystal structure, microstructure and electrical properties were investigated. Both the KNNT with Cs⁺ substitution (K_0.5-xCs_xNNT) and addition (KNNT-xCs) (x = 0, 0.01, 0.02, 0.03 and 0.04 mol%) were synthesized by the solid-state combustion technique using glycine as fuel. All samples were sintered at 1130–1150 °C for 4 h. The x-ray diffraction (XRD) analysis for the ceramics revealed the presence of orthorhombic (O) and tetragonal (T) phases in all samples. Increasing both the Cs⁺ substitution and doping amounts, enhanced the content of orthorhombic phase, as verified by the Rietveld refinement technique. It was found that Cs⁺ doping, either substitutional or additional, strongly decreased their density, dielectric and ferroelectric properties. The undoped KNNT ceramic exhibited well-saturated P-E hysteresis loop. With Cs⁺ doping, the samples became unsaturated and a leakage current was produced. The KNNT-xCs ceramics demonstrated higher density and dielectric properties than the K_0.5-xCs_xNNT ceramics.

KEYWORDS:

• KNNT
• phase evolution
• Rietveld refinement
• solid-state combustion technique

This work was financially supported by The National Science, Research and Innovation Fund (NSRF) through Naresuan University (R2565B059). The authors wish to thank the Department of Physics, Faculty of Science, Naresuan University for their supporting facilities. Thanks are also given to Asst. Prof. Dr. Kyle V. Lopin for his help in editing the manuscript.