Low‐Temperature Preparation of Ultrafine Rare‐Earth Iron Garnets

Abstract

Ultrafine rare-earth iron garnets, (R3Fe50t2 where R = Sm, Tb, Dy, Ho, Er, Yb, (YGd), and (YNd)) have been prepared by thermal decomposition of a citrate precursor, R3Fe5(cit)zs -(36 + n)H20. 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 m2/g have been obtained and characterized by XRD, TEM, Mossbauer 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.[

Synthesis and Characterization of Yttrium Iron Garnet Nanoparticles

“…This process involves extensive treatments at high temperature and repeated mechanical mixing to achieve the desired phase purity. Other techniques for synthesizing garnets using hydroxide coprecipitation (2), hydrolysis of metal alkoxides (3), or decomposition of a citrate gel (4,5) have been developed. In these methods, the reactant cations are intimately mixed on the atomic scale, so the rate of the reaction will be increased, leading to lower synthesis temperatures and smaller particles.…”

Mössbauer and magnetic studies of nanocrystalline γ ′-Fe4N

“…Thermal decomposition of metal citrate complexes showed the formation of oxide nanoparticles [6,7]. The reaction of these oxide nanoparticles with NH 3 gas lead to the formation of metal nitrides [8,9].…”

Magnetic properties of iron nitride-alumina nanocomposite materials prepared by high-energy ball milling

“…After four hours of milling with Al 2 O 3 , δ increases to 0.30 mm/s, a value close to that of pure Fe 3 N. Although the particle diameter of (Fe x N) 4 can be attributed to the lower s-electron density. This increase in isomer shift is believed to be due to the reduced s-electron density at the grain boundaries, the reduced particle sizes, and the strain in the crystal lattice [27,28].…”