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Phase Formation and Solid State Structure on Calcination of a Nickel Ferrite Acetate Precursor
Author(s) -
Heegn H.,
Trinkler M.,
Langbein H.
Publication year - 2000
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/1521-4079(200003)35:3<255::aid-crat255>3.0.co;2-d
Subject(s) - calcination , nanocrystalline material , spinel , materials science , amorphous solid , crystallite , crystallization , chemical engineering , grain size , nickel , annealing (glass) , thermal decomposition , mineralogy , agglomerate , ferrite (magnet) , metallurgy , crystallography , composite material , chemistry , nanotechnology , organic chemistry , catalysis , engineering
The thermal decomposition of a freeze dried Ni‐Fe‐μ‐oxo‐acetate results in the formation of an amorphous nickel ferrite. Crystallization of the spinel NiFe 2 O 4 takes place between 300 and 500°C. High disperse amorphous (or less crystalline) products with specific surfaces up to 500 m 2 /g can be obtained by carful decomposition between 260 and 300°C. Raising the calcination temperature and calcination time effects a decrease of porosity and of the specific surface. The primary nanocrystalline spinel powder is strongly agglomerated. During an annealing process between 300 and 500°C the crystallite size is increased but the mean diameter of agglomerates of about 15 μm does not change. A combination of milling and ultrasonic dispersion allows the adjustment of grain sizes < 1 μm with a narrow grain size distribution.