Abstract
The Ni and Fe doping effect on the structural and magnetocaloric properties of
La
0.8
Na
0.2
MnO
3
is investigated. The nanoparticles
La
0.8
Na
0.2
Mn
0.97
Fe
0.03
O
3
and
La
0.8
Na
0.2
Mn
0.97
Ni
0.03
O
3
manganite oxide were synthesized using sol–gel route. X-ray diffraction analysis (XRD) shows that both specimens belong to the R
3
¯
c space group of the rhombohedral distorted perovskite structure. Indeed, we deduced that both compositions present a second-order ferromagnetic (FM) — paramagnetic (PM) transition phase around
T
c
= 261 K and 275 K for
La
0.8
Na
0.2
Mn
0.97
Fe
0.03
O
3
and
La
0.8
Na
0.2
Mn
0.97
Ni
0.03
O
3
samples, respectively. The maximum magnetic entropy change value, determined from Maxwell relation, is found to be 3.6 and 3.7
Jkg
-
1
K
-
1
corresponding to a relative cooling power RCP value about 61.2% and 68.6% for Fe- and Ni-doped element, respectively. We improved that the universal data analysis proved that our compositions present a critical transition characterized by a second-order phase.