Abstract
Direct and indirect measurements of the magnetocaloric effect in La
0.7
Pb
0.3-
x
Ba
x
MnO
3
(
x
= 0.05, 0.10, and 0.15) manganite were reported. The effect of Pb substitution with Ba on the structural, magnetic, and magnetocaloric properties of these compounds was investigated. The X-ray analysis reveals a structural transition upon doping. The rhombohedral structure of
x
= 0.05 is transformed into a mixture of cubic and rhombohedral phases for both samples
x
= 0.10 and
x
= 0.15. For all the samples, magnetic versus temperature analysis shows a transition from a paramagnetic (PM) to a ferromagnetic state (FM). The zero-field heat capacity measurement was also performed. The magnetocaloric efficiency was determined from adiabatic temperature and isothermal magnetization curves using Maxwell relation. It is found that the sample with the composition
x
= 0.10 exhibits the highest value of ΔT
ad
and ΔS
m
which were found to be 1.75 K and 1.445 Jkg
−1
K
−1
at 3 T respectively. The corresponding relative cooling power (RCP) was around 145.5 Jkg
−1
. The phenomenological construction of the universal curves and the Banerjee criterion revealed a second-order phase transition for all samples.