MAGNETOCALORIC EFFECT AND MAGNETIC PROPERTIES OF Pr₁₋ₓ Ceₓ Co₃ COMPOUNDS

Souca, Gabriela; Iamandi, S.; Mazilu, C.; Dudric, Roxana; Tetean, R.

doi:10.24193/subbphys.2018.01

Cited by 4 publications

(3 citation statements)

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“…This is explained by the existence of local minima and maxima on Initial observation reveals that the value for TEC for all polycrystalline samples diminishes with increasing temperature span ∆T H-C . This tendency has been reported in previous research [51][52][53] and is expected, as the graphs for magnetic entropy change in bulk have a smooth Gaussian-like distribution. Nano-sized samples, on the other hand, show a small fluctuation around a mean value, which also diminishes, but very slowly, with increasing ∆T H-C .…”

Section: Magnetic Propertiessupporting

confidence: 87%

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Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Bulk Manganites La0.7Ba(0.3−x)CaxMnO3 (x ≤ 0.25)

Atanasov,

Brinza,

Bortnic

et al. 2023

Magnetochemistry

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Here we report the synthesis and investigation of bulk and nano-sized La0.7Ba0.3−xCaxMnO3 (x = 0, 0.15, 0.2 and 0.25) compounds that are promising candidates for magnetic refrigeration applications. We compare the structural and magnetic properties of bulk and nano-scale polycrystalline La0.7Ba0.3−xCaxMnO3 for potential use in magnetic cooling systems. Solid-state reactions were implemented for bulk materials, while the sol–gel method was used for nano-sized particles. Structurally and morphologically, the samples were investigated by X-ray diffraction (XRD), optical microscopy and transmission electron microscopy (TEM). Oxygen stoichiometry was investigated by iodometry. Bulk compounds exhibit oxygen deficiency, while nano-sized particles show excess oxygen. Critical magnetic behavior was revealed for all samples using the modified Arrott plot (MAP) method and confirmed by the Kouvel–Fisher (KF) method. The bulk polycrystalline compound behavior was better described by the tricritical field model, while the nanocrystalline samples were governed by the mean-field model. Resistivity in bulk material showed a peak at a temperature Tp1 attributed to grain boundary conditions and at Tp2 associated with a Curie temperature of Tc. Parent polycrystalline sample La0.7Ba0.3MnO3 has Tc at 340 K. Substitution of x = 0.15 of Ca brings Tc to 308 K, and x = 0.2 brings it to 279 K. Nanocrystalline samples exhibit a very wide effective temperature range in the magnetocaloric effect, up to 100 K. Bulk compounds exhibit a high and sharp peak in magnetic entropy change, up to 7 J/kgK at 4 T at Tc for x = 0.25. To compare the magnetocaloric performances of the studied compounds, both relative cooling power (RCP) and temperature-averaged entropy change (TEC) figures of merit were used. RCP is comparable for bulk polycrystalline and nano-sized samples of the same substitution level, while TEC shows a large difference between the two systems. The combination of bulk and nanocrystalline materials can contribute to the effectiveness and improvement of magnetocaloric materials.

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Section: Magnetic Propertiessupporting

confidence: 87%

“…Magnetic entropy change was calculated from magnetization M(µ 0 H,T) isotherm data at external fields of 1 T, 2 T, 3 T and 4 T using the following formula [42,43]:…”

Section: Magnetic Propertiesmentioning

confidence: 99%

Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Bulk Manganites La0.7Ba(0.3−x)CaxMnO3 (x ≤ 0.25)

Atanasov,

Brinza,

Bortnic

et al. 2023

Magnetochemistry

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“…It is evident, that the lines in KF plots are close to being straight and their slope values result in β and γ being close to results from MAP. Magnetic entropy change was calculated using the following formula [50,51]:…”

Section: Magnetic Propertiesmentioning

confidence: 99%

Magnetic Properties and Magnetocaloric Effect of Polycrystalline and Nano-Manganites Pr0.65Sr(0.35−x)CaxMnO3 (x ≤ 0.3)

et al. 2023

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Here we report investigations of bulk and nano-sized Pr0.65Sr(0.35⁻x)CaxMnO3 compounds (x ≤ 0.3). Solid-state reaction was implemented for polycrystalline compounds and a modified sol–gel method was used for nanocrystalline compounds. X-ray diffraction disclosed diminishing cell volume with increasing Ca substitution in Pbnm space group for all samples. Optical microscopy was used for bulk surface morphology and transmission electron microscopy was utilized for nano-sized samples. Iodometric titration showed oxygen deficiency for bulk compounds and oxygen excess for nano-sized particles. Measurements of resistivity of bulk samples revealed features at temperatures associated with grain boundary condition and with ferromagnetic (FM)/paramagnetic (PM) transition. All samples exhibited negative magnetoresistivity. Magnetic critical behavior analysis suggested the polycrystalline samples are governed by a tricritical mean field model while nanocrystalline samples are governed by a mean field model. Curie temperatures values lower with increasing Ca substitution from 295 K for the parent compound to 201 K for x = 0.2. Bulk compounds exhibit high entropy change, with the highest value of 9.21 J/kgK for x = 0.2. Magnetocaloric effect and the possibility of tuning the Curie temperature by Ca substitution of Sr make the investigated bulk polycrystalline compounds promising for application in magnetic refrigeration. Nano-sized samples possess wider effective entropy change temperature (ΔTfwhm) and lower entropy changes of around 4 J/kgK which, however, puts in doubt their straightforward potential for applications as magnetocaloric materials.

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Influence of Cu addition on the structural, magnetic and magnetocaloric properties of the PrCo3 intermetallic compound

Mican

One

Pop

et al. 2022

Journal of Alloys and Compounds

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MAGNETOCALORIC EFFECT AND MAGNETIC PROPERTIES OF Pr₁₋ₓ Ceₓ Co₃ COMPOUNDS

Cited by 4 publications

References 0 publications

Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Bulk Manganites La0.7Ba(0.3−x)CaxMnO3 (x ≤ 0.25)

Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Bulk Manganites La0.7Ba(0.3−x)CaxMnO3 (x ≤ 0.25)

Magnetic Properties and Magnetocaloric Effect of Polycrystalline and Nano-Manganites Pr0.65Sr(0.35−x)CaxMnO3 (x ≤ 0.3)

Influence of Cu addition on the structural, magnetic and magnetocaloric properties of the PrCo3 intermetallic compound

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