4 Conclusions
La0.7Sr0.3MnO3 nanoparticles with particle sizes of 18–
55 nm have been synthesized by a simple thermal decomposition
method using acetate salts in DI water. The structural
characterization showed that the prepared particles consist
of two main phases of LaMnO3 and La0.7Sr0.3MnO3. All
the prepared samples have a perovskite structure which
changes from cubic to rhombohedral with the increase in
the thermal decomposition temperature. The study of magnetic
properties at room temperature show that MS and HC
depend strongly on the particle size. The magnetic measurement
results indicate that there is an incomplete substitution
of Sr for La site in perovskite structure. The samples
show a soft ferromagnetic behavior with MS values of ∼9–
55 emu/g and HC values of ∼8–37 Oe, depending on the
crystallite size and thermal decomposition temperature. The
samples with the crystallite size smaller than 40 nm contain
single magnetic domain particles, whereas the sample with
particle size larger than 40 nm has multi-ferromagnetic domains.
In addition, the magnetic nanoparticles showed no
toxicity to the tested cells, NIH 3T3, as determined from the
result of cell viability in response to the liquid extraction
of the magnetic nanoparticles. This may be useful for medical
applications. The present work proves that the hydrothermal
decomposition is a new useful method for preparation
of manganite nanoparticles, and gives a potential avenue
for further practical scale-up of the production process
and applications.