Effect of iron substitution on the structural, magnetic and magnetocaloric properties of Pr0.6Ca0.1Sr0.3Mn1−xFexO3 (0⩽x⩽0.075) manganites (original) (raw)
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The effect of Iron (Fe) doping on the structural, magnetic and magnetocaloric properties of poly-crystalline samples of Pr 06 Sr 04 MnO 3 was investigated. Doped samples Pr 06 Sr 04 Mn 1−x Fe x O 3 with two different amounts of iron (x = 005, 0.1) as well as a pure undoped sample were prepared using the conventional solid state reaction method and were thoroughly investigated and compared. The X-rays diffraction analysis (XRD) established an orthorhombic structure with Pbnm space group in all samples. A second order nature of magnetic transition was confirmed using magnetization measurements and Arrott plots. A decrease in magnetization and Curie temperature was observed in the samples with higher amount of iron. A maximum value of magnetic entropy change 2.76 Jkg −1 k −1 at an applied magnetic field of 2.5 T and a relative cooling power (RCP) of 127 Jkg −1 was observed in parent sample. The large magnetic entropy change, soft ferromagnetic properties and large RCP values make these compounds potential candidates for magnetic refrigeration.
Journal of Rare Earths
A systematic investigation on the structural, magnetic and magnetocaloric properties of Pr0.6Sr0.4-xAgxMnO3 (x=0.05 and 0.1) manganites was reported. Rietveld refinements of the X-ray diffraction patterns confirmed that all samples were single phase and crystallized in the orthorhombic structure with Pnma space group. Magnetic measurements in a magnetic applied field of 0.01 T revealed that the ferromagnetic-paramagnetic transition temperature TC decreased from about 293 to 290 K with increasing silver content from x=0.05 to 0.1. The reported magnetocaloric entropy change and relative cooling power for both samples were considerably remarkable with a ∆Smax value of 1.9 J/(kg•K) and maximum RCP values of 100 J/kg, under a magnetic field change (Δµ0H) equal to 1.8 T. The analysis of the universal curves gave an evidence of a second order magnetic transition for the studied samples. The magnetic field influence on both the magnetic entropy change and the relative cooling power was also studied and discussed.
This article covers the detailed study on the magnetic and magnetocaloric properties of Pr 0.5 Eu 0.1 Sr 0.4 MnO 3 samples. The materials were synthesized through the sol–gel using nitrate–citrate route method by sintering at four different temperatures starting from 600 to 1000 °C. Phase purity, structure, size, and crystallinity were investigated using XRD and SEM. The structure, magnetic properties and magnet-ocaloric effect of Pr 0.5 Eu 0.1 Sr 0.4 MnO 3 ceramics with different particle sizes have been investigated. Regardless of the sintering temperature, the orthorhombic crystal structure with the Pnma space group is stable. XRD analysis showed that the particle size increases with the increase in sintering temperature. The Curie temperature shifted from 90 K to 270 K. Magnetization, magnetic entropy change (DS), and relative cooling power (RCP) also increased with size in the nanocrystalline samples. The magnetic entropy changes were about 0.89 J/kg K, 2.75 J/kg K, 3.34 J/kg K, and 3.82 J/kg K for the samples sintered at 600 °C, 800 °C, 900 °C and 1000 °C, respectively when a magnetic field of 5 T was applied. It is shown that for Pr 0.5 Eu 0.1 Sr 0.4 MnO 3 the magnetic entropy change follows a master curve behavior.
Magnetic and magnetocaloric properties of Pr0.6−xEuxSr0.4MnO3 manganese oxides
Solid State Communications, 2011
Studies of the structural, magnetic and magnetocaloric properties of polycrystalline Pr 0.6−x Eu x Sr 0.4 MnO 3 (0 ≤ x ≤ 0.15) perovskite manganites were carried out. Substitution for praseodymium with europium, with smaller ionic radius, induces local distortion in the ⟨Mn-O-Mn⟩ bonds and consequently causes a random distribution in the magnetic exchange interactions. The competition between magnetic interactions leads to the appearance of an inhomogeneous magnetic state in our samples.
Journal of Nanoscience and Nanotechnology, 2011
We present an investigation on magnetic and magnetocaloric properties of nano-sized La 0.8 Ca 0.2 Mn 1-x-Fe x O 3 (x = 0, 0.01, 0.15, 0.2) manganites synthesized by sol-gel process. X-ray diffraction and magnetization measurements were performed to investigate both crystallographic structure and magnetocaloric properties, respectively. All samples show an orthorhombic structure with Pnma space group. Ferromagnetic-paramagnetic transition sensitive to iron doping is observed at Curie temperature (T C) ranging from 223 K (x = 0) to 70 K (x = 0.2). In addition, a large magnetocaloric effect near T C is observed. Under a magnetic field change of 5 T, a maximum of magnetic entropy DS max M reaches 4.42, 4.32, 1.6, and 0.54 J kg-1 K-1 , for x = 0, x = 0.01, x = 0.15, and x = 0.2, respectively. The relative cooling power (RCP) values were computed as well. RCP values of 164 and 117 J kg-1 were found for La 0.8 Ca 0.2 MnO 3 (LCM) and La 0.8 Ca 0.2 Mn .0.99 Fe 0.01 O 3 (LCMFe 0.01), respectively. The large values of entropy changes and related RCP allow concluding that our material could be a highly attractive candidate for magnetic refrigeration.
Magnetocaloric study of monovalent-doped manganites Pr0.6Sr0.4−x Na x MnO3 (x = 0–0.2)
Journal of Materials Science, 2013
A systematic investigation of structural, magnetic, and magnetocaloric properties is reported for a series of monovalent sodium-doped manganites Pr 0.6 Sr 0.4-x Na x MnO 3 (x = 0, 0.05, 0.1, 0.15, and 0.2). Rietveld refinements of the X-ray diffraction patterns show that all powder samples are single-phased and crystallized in the orthorhombic structure with Pnma space group. Magnetic characterization and Arrott plot confirm the second-order phase transition at Curie temperature T C decreasing from 310 K for x = 0 down to 272 K for x = 0.2. Magnetic entropy change is largest for x = 0 reaching 1.95 J kg-1 K-1 at 2 T field. This corresponds to a large relative cooling power of 102 J kg-1. Magnetic field sensitivity of magnetic entropy change and relative cooling power are analyzed and discussed.
Journal of Alloys and Compounds, 2016
research in the last few years since the discovery of the phenomenon of colossal magnetoresistance (CMR) in these systems. The CMR is usually explained with double-exchange (DE) mechanism [1] and the CMR materials have potential applications such as in magnetic switching or recording devices, etc. However, the intrinsic CMR effect is usually found in the condition of several magnetic fields and a narrow temperature range near the Curie temperature (T C) [2]. This magnetic field and temperature range is incapable of practical application. Recently, another type of MR called the inter-grain MR (IMR) has also been a research focus found in polycrystalline half metallic ferromagnets, which is associated with the spin-dependent charge transport across the grain boundaries [3-7]. Compared with the CMR in single crystals, the IMR in polycrystalline usually occurs over a wider temperature range and at a lower magnetic field below T C , which is usually called low-field magnetoresistive (LFMR). Compared with CMR, LFMR may be more useful for practical application. The change in the valence of the perovskite A-site or the band filling, significantly affects the magnetism and conductivity of these manganites [8, 9]. Recent investigations have demonstrated that variations in A-site ions play important roles in the magnetic and transport properties of these manganites for a given carrier doping [10, 11]. A direct relationship between the average ionic radius for A-site ions and the Curie temperature T C has already been established [12]. Among various manganites with perovskite structure, La 0.7 Sr 0.3 MnO 3 (LSM) is a prototype DE ferromagnet and it is mostly metallic and therefore has most itinerant electrons. Replacement of Sr by Ca results in a distortion of MnO 6 octahedra (hence increase of electron-phonon coupling), which lowers T C with increase of resistivity of the La 0.7 Ca 0.3 MnO 3 (LCM) system. It is well known that the T C
Journal of Magnetism and Magnetic Materials, 2020
The structural, magnetic and magnetocaloric properties are investigated in details for the GdFeO 3-type Pr 0.5 Eu 0.1 Sr 0.4 MnO 3 and Pr 0.5 Er 0.1 Sr 0.4 MnO 3 manganites (oP20, space group Pnma, N 62). Landau analysis, Banerjee's criteria, and universal behaviour are studied to assess magnetic ordering in the samples. These methods reveal the occurrence of a second-order phase transition and the short-range interactions in the vicinity of Curie temperatures. The maximum of the magnetic entropy change ΔS M (field change of 5 T) is found to increase from 4.47 J/kg.K at T C = 279.9 ± 1 K to 4.86 J/kg.K at T C = 188.5 ± 1 K for Pr 0.5 Eu 0.1 Sr 0.4 MnO 3 and Pr 0.5 Er 0.1 Sr 0.4 MnO 3 , respectively with corresponding relative cooling power (RCP) 264.8 J/kg to 270.9 J/ kg.