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Room‐Temperature Sol–Gel Synthesis of Sodium Hexaniobate in an Immiscible Hexane–Water System and Its Conversion into NaNbO 3
Author(s) -
Tanaka Masahiro,
Fujihara Shinobu
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201101329
Subject(s) - chemistry , aqueous solution , dissolution , hexane , phase (matter) , sodium , niobium , chemical engineering , ethanol , mixing (physics) , inorganic chemistry , chromatography , organic chemistry , physics , quantum mechanics , engineering
Sodium hexaniobate (Na 7 [HNb 6 O 19 ] · 15H 2 O) was synthesized by a one‐pot sol–gel method at room temperature by using an immiscible, biphasic solution. An organic solution was prepared by dissolving niobium pentaethoxide [Nb(OC 2 H 5 ) 5 ] in ethanol, which was then added to hexane. This solution was brought into contact with an aqueous NaOH solution to form a reaction system consisting of two separate phases. A white precipitate was formed within 12 h at the bottom of the aqueous solution. It exhibited well‐defined rod‐like morphology on a micrometer scale. A comparative study was performed on the basis of a single‐phase solution by mixing Nb(OC 2 H 5 ) 5 in ethanol and the aqueous NaOH solution. The results indicated that the product formed by way of the single‐phase solution was rather different in morphology from that obtained in the biphasic system. In both cases, Na 7 [HNb 6 O 19 ] · 15H 2 O could be converted to NaNbO 3 by heating at 600 °C. Mechanisms underlying the formation of Na 7 [HNb 6 O 19 ] · 15H 2 O and its conversion to NaNbO 3 are discussed on the basis of the experimental results.