Résumé

In this paper, the physical characteristics of La0.5Ag0.1Ca0.4MnO3
and La0.6Ca0.3Ag0.1MnO3
compounds have been studied. Structural analysis by XRD showed that both samples crystallize
in an orthorhombic structure. For the La0.5Ag0.1Ca0.4MnO3
sample it can be seen
that there are two bands: the first is due to the stretching Mn–O bond the s vibration mode,
relates to the internal motion of a length-changing Mn–O, whereas the second corresponds
to the b bonding mode, which is sensitive to a change in the Mn–O–Mn angle. For the
compound La0.6Ca0.3Ag0.1MnO3
the b band is absent. The magnetic measurements show
that the two compounds have a single transition from the PM state to the FM state with
an increase in the Curie transition temperature Tc for the compound La0.6Ca0.3Ag0.1MnO3.
Similarly, the substitution of silver in calcium increases the value of the magnetization at
low temperature. We also studied the magnetocaloric effect of our compounds. This study
shows a significant change in magnetic entropy ΔSM that took place around their magnetic
transition temperatures Tc . Under the influence of a 5 T magnetic field. The largest
fluctuation in magnetic entropy is in the order of − 8.67 J/kg·K for the compound
La0.6Ca0.3Ag0.1MnO3
this value is considered significant. The magnetocaloric results indicate
that the compound La0.6Ca0.3Ag0.1MnO3
is the best sample which has a large RCP
which suggests its good candidate in the field of magnetic cold. Based on the Banarjee
criterion and Landau theory, a second-order transition is observed for both samples in the
vicinity of the Curie transition Tc . The experimentally obtained value of ΔSM is smaller
than the theoretically calculated one, which proves that the transition is an unconventional
transition even under the influence of a 5 T magnetic field.

Information

Item Type:	Journal
Divisions:
ePrint ID:	4403
Date Deposited:	2023-09-13
Further Information:	Google Scholar
URI:	https://www.univ-soukahras.dz/fr/publication/article/4403

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