Abstract
We present a detailed study on the physical properties of La
Ba
Sr
Mn
Ni
O
samples (
= 0.00, 0.05 and 0.1). The ceramics were fabricated using the sol-gel route. Structural refinement, employing the Rietveld method, disclosed a rhombohedral
3̄
phase. The magnetization
temperature plots show a paramagnetic-ferromagnetic (PM-FM) transition phase at the
(Curie temperature), which decreases from 354 K to 301 K. From the Arrott diagrams
/
, we can conclude the phase transition is of the second order. Based on measurements of the isothermal magnetization around
, the magnetocaloric effects (MCEs) have been calculated. The entropy maximum change (-Δ
) values are 7.40 J kg
K
, 5.6 J kg
K
and 4.48 J kg
K
, whereas the relative cooling power (RCP) values are 232 J kg
, 230 J kg
and 156 J kg
for
= 0.00, 0.05 and 0.10, respectively, under an external field (
) of 5 T. Through these results, the La
Ba
Sr
Mn
Ni
O
(0 ≤
≤ 0.1) samples can be suggested for use in magnetic refrigeration technology above room temperature. The electrical resistivity (
)
temperature plots exhibit a transition from metallic behavior to semiconductor behavior in the vicinity of
. The adiabatic small polaron hopping (ASPH) model is applied in the PM-semiconducting part (
>
). Throughout the temperature range,
is adjusted by the percolation model. This model is based on the phase segregation of FM-metal clusters and PM-insulating regions.