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Effect of Firing Conditions on Phase Formation, Microstructure, and Electrical Properties of (K0.5Na0.5)(Nb0.7Ta0.3)O3 Ceramics Synthesized by Solid-State Combustion Method
Author(s)
Yotthuan, Surirat
Charoonsuk, Thitirat
Thountom, Sarawut
Suriwong, Tawat
Udeye, Thanya
Bongkarn, Theerachai
Date Issued
October 1, 2020
Type
Article
Abstract
The effect of the firing conditions on the phase formation, microstructure, and electrical properties of (K0.5Na0.5)(Nb0.7Ta0.3)O3 (KNNT) ceramics synthesized by the solid-state combustion technique using glycine as fuel has been investigated. All samples were calcined at 600°C to 800°C for 2 h and sintered at 1150°C to 1190°C for 2 h to 5 h. Pure KNNT powders were produced after calcination at 600°C for 2 h. The average particle size increased when the calcination temperature was increased. The KNNT powder calcined at 600°C for 2 h showed rather square morphology with average particle size of ∼ 160 nm. The x-ray diffraction (XRD) analysis results for the ceramics revealed the presence of orthorhombic (O) and tetragonal (T) phases in all samples. When sintering at 1150°C for 4 h, the O:T ratio was 50:50, as verified by the Rietveld refinement technique. The average grain size, density values, and dielectric properties tended to increase when the dwell time was increased from 2 h to 4 h, but then degraded. The KNNT ceramic produced at the optimum firing condition (1150°C for 4 h) showed good crystalline morphology, the highest density (ρ = 5.28 g/cm3), the highest dielectric constant (εC = 5002), and good ferroelectric behavior (Pr = 18.50 μC/cm2 and Ec = 9.04 kV/cm).
Citation
Journal of Electronic Materials, 49(10), 6143-6155, 2020