Preparation and characterization of nanocrystalline disordered lithium ferrite by citrate precursor method

Abstract

Nanocrystalline Li 0.5Fe 2.5O 4 have been synthesized by citrate precursor gel formation method. DTA/TG measurements show that the metal citrates decomposed around 489 K followed by formation and crystallization of the ferrite. Nanoparticles with average particle size of 10 and 19 nm were obtained by sintering the samples at 573 and 773 K. XRD patterns show that both the sintered samples are single-phase cubic spinel oxide. XRD and FTIR show that 1:3 ordering is absent in these samples. Cation distribution of these samples show that only small amounts of Li l+ is present on the octahedral sites, and hence cation ordering in the octahedral site is not possible and the sample is disordered. Mössbauer studies show that the spectrum of the 19 nm sample can be fitted to two sextets corresponding to Fe 3+ on A and B sites, and large quadrupole splitting values are due to surface irregularities. The spectrum of the 10 nm sample was fitted to a number of symmetric sextets indicating large particle size distribution.