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Solid Solution Nanocrystals in the CeO 2 ‐ Y 3 NbO 7 System: Hydrothermal Formation and Control of Crystallite Growth of Ceria
Author(s) -
Hirano Masanori,
Minagawa Kosuke
Publication year - 2014
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13215
Subject(s) - solid solution , nanocrystal , hydrothermal circulation , natural bond orbital , fluorite , crystallography , materials science , phase (matter) , mineralogy , chemistry , chemical engineering , nanotechnology , computational chemistry , density functional theory , organic chemistry , engineering , metallurgy
New solid solution nanocrystals with fluorite‐type cubic structure in the ceria ( CeO 2 )‐yttrium niobate (1/4 Y 3 NbO 7 ) system were directly formed at 120°C–240°C from the precursor solution mixtures of ( NH 4 ) Ce ( NO 3 ) 6 , YCl 3 ·6 H 2 O , and NbCl 5 under mild hydrothermal conditions in the presence of aqueous ammonia. The hydrothermal formation of cubic solid solution nanocrystals in the wide composition range of CeO 2 (mol%) = 10–100 in the CeO 2 –1/4 Y 3 NbO 7 system was effectively achieved via the assistance of the presence of CeO 2 component more than 10 mol% as a promoter with the same fluorite‐type structure. The optical band gap of the solid solutions gradually decreased with increased CeO 2 component. The high phase stability of the solid solutions in the CeO 2 –1/4 Y 3 NbO 7 system was confirmed, i.e., the single cubic phase of the solid solutions was maintained after heat treatment at 600°C–1500°C for 1 h in air. The presence of Y 3 NbO 7 as an inhibitor and the substitutional incorporation of Y 3 NbO 7 into the lattice, CeO 2 effectively controlled the crystallite growth of CeO 2 , and nano‐sized cubic solid solutions with high specific surface areas were maintained after heat treatment up to 800°C–1000°C for 1 h air.