Fig. 9 Cytotoxcity of La0.7Sr0.3MnO3 nanoparticles at the calcination
conditions of 800, 900, and 1000◦C was studied on NIH 3T3 cells.
Cells were incubated with the liquid extractions of nanoparticles or
water (control) for 24 h before cell viability was determined by MTT
assay
behavior with HC exhibiting a (crystallite size)−3/2 dependence
[19]. It can be seen from the inset of Fig. 8
(left) that the HC varies linearly with the inverse of the
(mean crystallite size)3/2 when the particle size is below
40 nm. This indicates that the samples with the crystallite
size smaller than 40 nm should be single magnetic domain,
whereas the sample with particle size greater than 40 nm has
multi-ferromagnetic domains. Therefore, the critical particle
size of our LSMO samples is around 40 nm. This is
quite smaller than the critical diameter value of 80 nm for
manganite reported by Sanchez et al. [20]. The properties
of the prepared samples in this study are summarized in Table
1.