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Thermal Stability of (K x Na y H 1– x – y ) 2 Ti 6 O 13 Nanofibers
Author(s) -
Cortie Michael B.,
Xiao Linda,
Erdei Laszlo,
Kealley Catherine S.,
Dowd Annette R.,
Kimpton Justin A.,
McDonagh Andrew M.
Publication year - 2011
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.201100651
Subject(s) - anatase , chemistry , thermogravimetric analysis , calcination , potassium , thermal stability , hydrothermal circulation , titanate , ammonium hydroxide , rutile , inorganic chemistry , sodium , scanning electron microscope , hydrothermal synthesis , analytical chemistry (journal) , photocatalysis , chemical engineering , materials science , catalysis , ceramic , organic chemistry , engineering , composite material
Potassium‐rich titanate nanofibers were produced by digesting TiO 2 in concentrated KOH solutions under hydrothermal conditions. The nanofibers were characterized by scanning electron microscopy, energy dispersive X‐ray spectroscopy, X‐ray diffraction, and thermogravimetric analysis. A hexatitanate structure was assigned, in contrast to the trititanate structure usually resulting from NaOH treatment of TiO 2 . The potassium cations could be exchanged with others, such as sodium, hydrogen, and ammonium. The potassium‐rich hexatitanate was found to be photocatalytic in its as‐synthesized condition. The thermal stability of the fibers during calcination was followed in situ using X‐ray diffraction and was found to be strongly dependent on the chemical composition. The potassium‐rich titanate converted to anatase at only 480 °C, whereas the hydrogen‐ and ammonium‐rich materials had to be heated to over 600 °C before conversion took place. Conversion was notably slowest in the ammonium‐rich material. Surprisingly, the sodium‐rich hexatitanate did not form anatase at temperatures up to 800 °C and instead recrystallized.