Preparation of needle- and plate-like NaTaO₃ by molten NaOH method

抄録

Needle- and plate-like NaTaO₃ have been synthesized at low temperatures (<500°C) in three steps by a molten NaOH method. First, Na₃TaO₄ precursor was synthesized by the reaction of Ta₂O₅ with a molten NaOH at 450°C for 50 h in air. Then, Na₃TaO₃ precursor reacted with H₂O to form needle-like Na₇(H₃O)Ta₆O₁₉·14H₂O and plate-like Na₈Ta₆O₁₉·24H₂O intermediates in the process to wash the excess NaOH in the crucible with H₂O. The needle-like Na₇(H₃O)Ta₆O₁₉·14H₂O was the major product. Then, these intermediates transformed to NaTaO₃ through dehydrate intermediates by heating at above 500°C. The obtained NaTaO₃ had needle- and plate-like morphology with a perovskite structure.