Effect of Ag doping on structural, magnetic and magnetocaloric properties of La0.65Ca0.35−xAgxMnO3 manganites

Large magnetic entropy change near room temperature in La0.7(Ca0.27Ag0.03)MnO3 perovskite

“…The entropy change value measured by the same author [15] for La 0.7 Sr 0.3−x Na x MnO 3 was found to be 2.04 J/kg K under a magnetic field change of 2 T. Again, they [16] measured the MCE in La 0.65 Ba 0.3 M 0.05 MnO 3 , and the | S M | max was found to be 1.3, 1.43, and 1.34 J/kg K upon a magnetic field change of 2 T for M = Na, Ag, and K, respectively, while they also showed the entropy change value to be about 1.6 J/kg K for La 0.7 Sr 0.1 Ag 0.2 MnO 3 at 315 K [17]. Finally, they [18] measured the MCE in La 0.65 Ca 0.35−x Ag x MnO 3 , and the maximum entropy change, | S M | max , corresponding to a magnetic field variation of 1 T, was found to be 1.65, 1.14. 1.01, and 0.89 J/kg K for x = 0.05, 0.1, 0.15, and 0.2, respectively.…”

“…5, which indicates that a much larger entropy change is to be expected at higher magnetic field, satisfying thereby the effects of spin-lattice coupling associated with changes in the magnetic ordering process in the samples [27]. Besides, we note that for the La 0.7 (Ca 0.3 )MnO 3 and La 0.7 (Ca 0.27 Ag 0.03 )MnO 3 samples, the maximum magnetic entropy change (5.71 at 251 K and 4.5 J/kg K at 263 K for a 2 T field) is larger, about 90% of that for pure Gd for a 2 T field change [28], and also larger than for many other perovskite materials [14][15][16]18,25,[29][30][31], but smaller than for the most conspicuous magnetocaloric material, Gd 5 (Si 2 Ge 2 ) [28]. In particular, these values are larger than the values reported by Koubaa et al [15][16][17]19].…”

Effect of Ba substitution on structural, electrical and thermal properties of La0.65Ca0.35−Ba MnO3 (0 ⩽x⩽ 0.25) manganites

“…For these compounds, the two characteristic transition temperatures, metal-insulator transition temperature (T MI ) and Curie temperature (T C ) are nearly same. In addition, it is found that T MI attains a maximum value with x % 0.35 in the La 1Àx Ca x MnO 3 system [15]. These compounds have a disadvantage that their Curie temperatures, T C ($270 K) are well below room temperature.…”

Magnetic and Magnetocaloric Properties of La0.67Pb0.33−x Ag x MnO3 Compounds

“…Pure Gd, which is considered a good material, exhibits an RCP value of 250 J/kg at 2 T [10], while Gd 5 (Si 2 Ge 2 ), which is considered the most conspicuous magnetocaloric material at room temperature, presents an RCP value of 130 J/kg at 2 T [36]. For the samples studied here, the RCP values are found to be 68.75, 84.24, 130 and 156.27 J/kg under the magnetic field variation of 1 T for x = 0, 0.05, 0.1 and 0.15, respectively.…”