Hydrothermal synthesis followed by post heat-treatment: A novel route for the fabrication of KCa2Nb3O10 layered compound

Due to unique properties, KCa2Nb3O10 compound has received great attention worldwide. High-temperature solid-state reaction is the common route for the synthesis of this compound. In order to propose a new low-temperature method (i.e. hydrothermal synthesis), which could improve the final properties of KCa2Nb3O10, this study has been planned and performed. The preliminary experiments in KOH-Nb2O5 and Ca(OH)(2)-Nb2O5 systems revealed that KCa2Nb3O10 could be hydrothermally synthesized from a KOH-Ca(OH)(2)-Nb2O5 system using an alkaline condition (i.e. 5 M < KOH < 10 M). However, the experimental results showed that the product only consisted of KNbO3 and Ca2Nb2O7 phases. To initiate the reaction between KNbO3 and Ca2Nb2O7, the obtained KNbO3-Ca2Nb2O7 mixture was heat-treated in an air atmosphere. The results showed that KCa2Nb3O10, with a high crystallinity and good purity, has been successfully obtained at 800 degrees C. This temperature is the lowest temperature, reported for the synthesis of KCa2Nb3O10 compound so far. The SEM investigations revealed that the obtained KCa2Nb3O10 powder has plate-like morphology due to its layered structure.