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Low‐Temperature Preparation of Ultrafine Rare‐Earth Iron Garnets
Author(s) -
Sankaranarayanan Vellancheri K.,
Gajbhiye Namdeo S.
Publication year - 1990
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/j.1151-2916.1990.tb05195.x
Subject(s) - crystallite , superparamagnetism , materials science , crystallization , thermal decomposition , amorphous solid , agglomerate , particle size , mineralogy , analytical chemistry (journal) , ultrafine particle , mössbauer spectroscopy , crystallography , magnetization , chemical engineering , metallurgy , chemistry , nanotechnology , composite material , physics , organic chemistry , chromatography , quantum mechanics , magnetic field , engineering
Ultrafine rare‐earth iron garnets, (R 3 Fe 5 O 12 where R = Sm, Tb, Dy, Ho, Er, Yb, (YGd), and (YNd)) have been prepared by thermal decomposition of a citrate precursor, R 3 Fe 5 (cit) 25 · (36 + n )H 2 O. The precursors decompose at lower temperatures, below 450°C, and are characterized using DTA, DSC, TG, and IR spectroscopy. Ultrafine amorphous garnets having particle size 10 to 35 nm and surface area 30 to 75 m 2 /g have been obtained and characterized by XRD, TEM, Mössbauer spectra, particle size analysis, and magnetic and surface area measurements. Superparamagnetism indicates the ultrafine characteristics of the garnet materials. The nature of crystallite aggregates and agglomerates is of special interest because it represents finite clusters. An intercrystallite bond exists between crystallites having 1.0‐ to 1.5‐nm size. The rupture of intercrystallite bonds during crystallization leads to monolith formation.