Topochemical Synthesis of Micron‐Platelet (Na_0.5K_0.5)NbO₃ Particles

Abstract

Micron‐scale platelet (Na, K)NbO3 particles were synthesized from the platelet precursor K4Nb6O17 in a KCl medium using a topochemical method . The salt took part in the reaction and affected the composition of the products. Stoichiometric (Na0.5K0.5)NbO3 could be accurately synthesized by controlling the amount of the reactant Na2CO3. X‐ray diffraction analysis revealed that the crystallographic {010} plane of K4Nb6O17 was converted into the pseudo‐cubic {001} plane of (Na0.5K0.5)NbO3. The polycrystalline Na0.5K0.5NbO3 particles exhibited a plate‐like shape with a high aspect ratio, and were suitable for preparing textured ceramics by the template grain growth process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Seed crystal of modified potassium sodium niobate prepared by simple molten salt synthesis

“…As shown in Figures and , all the steps of Figure were observed at the SEM images which exhibited the KNBN plates synthesized by SMSS. In addition, the size of large plates was approximately 300‐500 μm which was much larger than the other seeds which were synthesized by topochemical reaction (10‐20 μm) . It might be due to the composition difference.…”

“…Recently, with the rapid development of various devices, the attractive improvement of the piezoelectric performance has been continuously required in the electronics industry. In addition, Pb‐free piezoelectric ceramics have been also widely studied to replace Pb(Zr,Ti)O 3 (PZT)‐based ceramics owing to the global interest about environment . Among the Pb‐free ceramics, (K,Na)NbO 3 (KNN)‐based ceramics have gained considerable attention due to the high piezoelectric response which was observed in the textured microstructure.…”

“…However, until now, the seed crystals have been synthesized by the topochemical reaction, which might be difficult to be commercialized, in KNN-based materials. [10][11][12][13] Therefore, simple-and-cheap processes must be developed for the commercialization of the textured-KNN ceramics.…”

Synthesis of [10Ῑ]‐Oriented (Na1−xKx)NbO3 Platelets by Using Hydrothermally Produced (K8−8xNa8x)Nb6O19·nH2O Precursor

“…Platelets of <110> BaTiO 3 have been produced by the two‐step hydrothermal method using a K 0.8 Ti 1.73 Li 0.27 O 4 precursor with a plate‐like structure . (Na 0.5 K 0.5 )NbO 3 platelets have been produced from a K 4 Nb 6 O 17 precursor using the TMC method . However, in this work, simple formation processes of NKN platelets without the TMC method are reported.…”

Direct preparation of K0.5Na0.5NbO3 powders

“…It is difficult to obtain the desirable products, such as KNN powders with a molar ratio of K/Na/Nb=1:1:2, by determining the KOH/NaOH ratio in the process, because Na + more easily enters into the A-site of (K,Na)NbO 3 than K + . Besides, accurate composition KNN can not be prepared by topochemical microcrystal conversion method or molten-salt process when raw materials are mixed stoichiometricly [11][12]. How to get stoichiometic KNN solid solution powders has been paid more attention today.…”