Advantages of Low Partial Pressure of Oxygen Processing of Alkali Niobate: NaNbO₃

Abstract

This work focused on the processing of low oxygen partial pressure (low‐pO2) calcination and sintering with respect to NaNbO3 (NN) of one key member in ferroelectric (Na,K)NbO3. The high‐density NN ceramics were successfully prepared without any sintering additives using the low‐pO2 process. Comparing conventional air process, the low‐pO2 calcined NN powders showed lower defect concentration and higher densification. The low‐pO2 sintered NN ceramics had dielectric constant and dielectric loss performance at high temperatures. Furthermore, the low‐pO2 sintered NN ceramics indicated ferroelectric behavior, and both maximum polarization and strain improved to two to three times that of conventional air‐sintered NN ceramics. From this relatively simple compound, NN, the advantage of low‐pO2 is unambiguously demonstrated and points to its consideration. It is hypotheses as a kinetically controlled process that limits the volatility under low‐pO2 condition.

Base Metal Co-Fired Multilayer Piezoelectrics

“…When compared with the air-sintered NKN, the low pO 2 -sintered NKN samples obtained higher electrical resistivity, which further indicated that a higher amount of alkaline elements was retained in the NKN. Similarly, advantages were also noted in the sintering of the end member NaNbO 3 [67]. These results were consistent with the first principle calculation that was conducted by Shigemi and Wada [68,69], showing that the formation energy of alkaline vacancies increased when the atmosphere changed from air to low pO 2 .…”

Cold Sintering Process: A Novel Technique for Low‐Temperature Ceramic Processing of Ferroelectrics

“…Studies on sintering have received broad research attention worldwide and continue to be of interest today. [11][12][13][14][15][16] Therefore, developing low-temperature sintering techniques has driven global-wide research in scientific communities and industrial corporations during the past several decades. For many materials like general oxides, the sintering temperature is typically~1000°C, and the time necessary to sinter even a simple pellet of dense material can be up to several hours to several days.…”

Strategy for stabilization of the antiferroelectric phase (Pbma) over the metastable ferroelectric phase (P21ma) to establish double loop hysteresis in lead-free (1−x)NaNbO3-xSrZrO3 solid solution

“…1,2 As motivated by the need to design ecofriendly piezoelectric ceramics during the past decade, [3][4][5][6][7][8][9] the exploration of lead-free AFE dielectrics over the lead-containing ones, such as PbZrO 3 -based systems, has also evoked considerable interest. 2,[10][11][12][13][14] The NaNbO 3 -based ceramics have been extensively studied due to the intrinsic AFE nature of NaNbO 3 , which is commonly referred to as P phase (with space group Pbma) at ambient conditions. [15][16][17][18] However, the AFE characteristic double P-E hysteresis loops are rarely observed in these systems due to a metastable ferroelectric (FE) Q phase (with space group P2 1 ma), 18 which displays a comparable free-energy profile with the AFE P phase and can be easily induced, and hence prevent back-switching to the AFE state.…”