Metamagnetic transition and magnetocaloric effect in charge-ordered Pr0.68Ca0.32−xSrxMnO3 (x=0, 0.1, 0.18, 0.26 and 0.32) compounds

In this work, the structural and magnetic properties of the polycrystalline La 0.85 Ag 0.15 MnO 3 (LAM) and (La 0.80 Pr 0.20 ) 0.85 Ag 0.15 MnO 3 (LPAM) compounds prepared by the sol-gel method were investigated. The structural properties of both polycrystalline compounds were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray spectrum (EDX) methods. The XRD results showed that both samples crystallized in the hexagonal symmetry with R3c space group. The SEM images showed that the particles are closely packed with each other, and their size range from 0.5 to 2.0 μm with the average sizes of 1.23 and 1.03 μm, for LAM and LPAM, respectively. From the EDX spectrum, in both compounds, we did not see loss of any integrated elements during the sintering process and no other impurity elements. The magnetic properties were studied by employing temperature M(T ) and external magnetic field M(H ) dependence of magnetization measurements. Both compounds showed magnetic phase transition from paramagnetic to ferromagnetic phase. With the substitution of Pr for La, the Curie temperature, T C , decreased from 262 to 216 K. At a field change of 5 T, LAM and LPAM showed large magnetic entropy changes of 7.90 and 4.96 J kg −1 K −1 , respectively. Furthermore, their relative cooling power (RCP) values were found as 213.32 and .02 J kg −1 , respectively. These findings make both LAM and LPAM compounds as good candidates for the practical magnetic refrigeration.

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“…The RCP values for both samples were determined by (5), which are tabulated in Table 4 and plotted in Fig. 6a- [3].…”

Section: Fig 3 M(t ) For the (A)mentioning

confidence: 99%

Magnetocaloric Properties of La0.85Ag0.15MnO3 and (La0.80Pr0.20)0.85Ag0.15MnO3 Compounds

Ayaş

Akyol

Çetin

et al. 2015

J Supercond Nov Magn

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“…The physical properties of perovskite manganites have been thoroughly investigated and much effort has been expended to find the best combination of manganites with the largest MR effect. Therefore, in earlier studies, the effects of doping various elements into the manganites' A or B sites on the magnetotransport and MR properties has been extensively studied [5][6][7][8][9][10][11][12]. It was found that the MR effects of these compounds fall into two classes: intrinsic and extrinsic MR. Intrinsic MR is referred to as intragrain MR, which has a maximum near the Curie temperature and can be qualitatively explained by the Double-Exchange model [11,12].…”

Section: Introductionmentioning

confidence: 99%

Electrical Transport and Magnetoresistance of La_0.67Ca_0.33MnO₃: Ag_x(x = 0, 0.1, 0.2, 0.3, 0.4) Composites

Gencer¹,

Pektas²,

Babur³

et al. 2012

Journal of Magnetics

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The structural, magnetic and magnetotransport properties of La 0.67 Ca 0.33 MnO 3 : Ag x (x = 0, 0.1, 0.2, 0.3 and 0.4) composites were investigated systematically. X-ray and EDX analysis indicated that Ag is not substituted into the main La 0.67 Ca 0.33 MnO 3 phase and remains an additive to the second phase at the grain boundary. The Curie temperature first decreased from 269 K for x = 0 to 257 K for x = 0.1 and then remained nearly unchanged with increasing Ag content. For the x > 0.1 samples, a second transition temperature (T MI2 ) was observed in the resistance curves. At temperatures below 150 K, a significant enhancement in MR was observed while high temperature MR decreased with increasing Ag content. The maximum MR was observed to be 55% in the x = 0.4 sample at 10 K and a 6T magnetic field, this value is larger than that of pure La 0.67 Ca 0.33 MnO 3 (53% at 265 K and 6 T). In addition, at low fields (H < 1T), a sharp increase in the MR was observed.

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“…The sample is blocked in a metastable PS state due to the disorder or the strains between the FM and CO-AFM states. With the increase in temperature, the system becomes unblocked due to the thermal uctuation and the magnetization shows a small increase [5,6]. .…”

Section: Methodsmentioning

confidence: 99%

Field Induced Unusual Magnetic Behavior at Low Temperature in Pr_0.67Ca_0.33MnO₃

et al. 2014

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In this study, magnetic properties of Pr0.67Ca0.33MnO3 compound were investigated in detail. The magnetization versus temperature (M T ) curve showed that this material undergoes a charge order transition at 200 K. A more pronounced FM phase appeared below 56 K. At T = 5 K, a eld induced sharp step like magnetisation transition associated with phase separation was observed. However, after application of 7 T magnetic eld at 5 K, the magnetic behaviour of sample was changed completely and full FM behaviour was observed. The more interesting is that the sample remains in the FM state and does not retrieve the initial magnetic state until warmed up to charge order transition temperature. Large negative magnetic entropy change (−26.18 J/(kg K) at 38 K and 5 T) was attributed to step like magnetisation transition.

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Metamagnetic transition and magnetocaloric effect in charge-ordered Pr0.68Ca0.32−xSrxMnO3 (x=0, 0.1, 0.18, 0.26 and 0.32) compounds

Cited by 77 publications

References 33 publications

Magnetocaloric Properties of La0.85Ag0.15MnO3 and (La0.80Pr0.20)0.85Ag0.15MnO3 Compounds

Magnetocaloric Properties of La0.85Ag0.15MnO3 and (La0.80Pr0.20)0.85Ag0.15MnO3 Compounds

Electrical Transport and Magnetoresistance of La_0.67Ca_0.33MnO₃: Ag_x(x = 0, 0.1, 0.2, 0.3, 0.4) Composites

Field Induced Unusual Magnetic Behavior at Low Temperature in Pr_0.67Ca_0.33MnO₃

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Metamagnetic transition and magnetocaloric effect in charge-ordered Pr0.68Ca0.32−xSrxMnO3 (x=0, 0.1, 0.18, 0.26 and 0.32) compounds

Cited by 77 publications

References 33 publications

Magnetocaloric Properties of La0.85Ag0.15MnO3 and (La0.80Pr0.20)0.85Ag0.15MnO3 Compounds

Magnetocaloric Properties of La0.85Ag0.15MnO3 and (La0.80Pr0.20)0.85Ag0.15MnO3 Compounds

Electrical Transport and Magnetoresistance of La0.67Ca0.33MnO3: Agx(x = 0, 0.1, 0.2, 0.3, 0.4) Composites

Field Induced Unusual Magnetic Behavior at Low Temperature in Pr0.67Ca0.33MnO3

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Electrical Transport and Magnetoresistance of La_0.67Ca_0.33MnO₃: Ag_x(x = 0, 0.1, 0.2, 0.3, 0.4) Composites

Field Induced Unusual Magnetic Behavior at Low Temperature in Pr_0.67Ca_0.33MnO₃