The grain growth mechanisms for 0.8(Bi,Na)TiO₃-0.2(Sr,Ti)O₃ ceramics prepared using a two-step sintering process

Figures & data

Figure 1. FE-SEM micrographs and distribution of the BNT–ST ceramics after the conventional sintering at sintering temperatures of (a) 1125°C, (b) 1150°C, (c) 1175°C, (d) 1200°C, and (e) 1225°C and (f) FE-SEM micrographs of the BNT–ST powder before the sintering process.

Figure 2. Relative density and average grain size of the BNT–ST ceramics as a function of the sintering temperature after the conventional sintering process.

Figure 3. Plots of grain size versus sintering temperature for estimating Q after the conventional sintering process.

Figure 4. Piezoelectric charge coefficient, d₃₃ and electromechanical coupling coefficients, k_p of the BNT–ST ceramics after conventional sintering at sintering temperatures of 1125°C, 1150°C, 1175°C, 1200°C, and 1225°C.

Figure 5. Average grain size and relative density of the BNT–ST ceramics as a function of t₂ of the secondary sintering process.

Figure 6. Ln G versus t₂ plots for estimating the grain growth kinetic exponent (n) after two-step sintering.

Table 1. Average grain size, n, and Q values based on the two-step sintering process.

Holding time, t2 (h)	Average grain size (nm)	n	Q (kJ/mol)
6	2284	2.27	422.00
12	2709	2.29	425.56
18	3070	2.41	444.66
24	3376	4.00	712.16
30	3557	4.01	714.12
36	3716	3.99	710.57

Figure 7. FE-SEM micrographs and grain size distribution of the BNT–ST ceramics after two-step sintering at various t₂: (a) 0 h, (b) 6 h, (c) 12 h, (d) 18 h, (e) 24 h, (f) 30 h, and (g) 36 h.

Figure 8. Piezoelectric charge coefficient, d₃₃ and electromechanical coupling coefficients, k_p of the BNT–ST ceramics after two-step sintering for various t₂ of 0 h, 6 h, 12 h, 18 h, 24 h, 30 h, and 36 h.