Synthesis and characterization of lead-free piezoelectric (K0.50Na0.50)NbO3 powder produced at lower calcination temperatures: A comparative study with a calcination temperature of 850 °C

Effect of Synthesis and Sintering Temperatures on K0.5Na0.5NbO3 Lead-Free Piezoelectric Ceramics By Microwave Heating

“…At temperatures above 730 °C, the carbonates have been completely transformed [19]. This temperature is consistent with the synthesis temperature reported in several studies [17,19], in the range of 700-750 °C.…”

“…At temperatures close to 511 ºC, the formation of a surface layer of (K, Na)2Nb4O11 in Nb2O5 has been reported, coinciding with a small isothermal reaction around 534 ºC. This is the first decomposition step of the carbonate mixture [17].…”

“…However, the particle size obtained by the microwave method has a bimodal distribution: large grains close to 3 µm surrounded by small grains of 0.5-1.0 µm. During conventional sintering, it is possible to see a liquid phase in early sintering stages in KNN materials, which is responsible for the grain growth [17,24,29,30].…”

Effect of Microwave-Assisted Synthesis and Sintering of Lead-Free KNL-NTS Ceramics

“…From 760 °C no further weight loss occurs, indicating the end of the reaction. The temperature obtained agrees with the calcination temperature reported by other authors, which is in the range of 700–800 °C [ 22 , 25 ]. Therefore, the temperature range between 650 °C and 800 °C was selected for the calcination studies of the powders by conventional and microwave processes.…”

“…Sintering of the KNL-NTS materials was carried out from powders calcined at 800 °C for 2 h by the conventional method [ 25 , 26 ]. This choice is due to the previous study where it has been shown that under these conditions the pure perovskite phase predominates and there is no formation of secondary phases.…”