We have synthesized La0.7 NdxBa(0.3-x)MnO3 (x = 0, 0.05, 0.1) perovskite manganites by using sol-gel method and investigated structure, magnetic and magnetocaloric properties. Structural analysis ...revealed that La0.7Ba0.3MnO3 and La0.7Nd0.05Ba0.25MnO3 have cubic and La0.7Nd0.1Ba0.2MnO3 rhombohedral structure. The Curie temperature of the samples decreased with increasing Nd content and equals to 303, 293 and 257 K for x = 0, 0.05, 0.1, respectively. We present experimentally by using magnetization isotherms and heat-capacity measurements that room temperature magnetic refrigeration is successfully achieved for La0.7Nd0.05Ba0.25MnO3 structure by tuning the Mn3+ to Mn4+ ratio. Additionally, zero-field and field-dependent heat-capacity measurements were compared to investigate the accuracy of the value of the adiabatic temperature-change.
•Magnetocaloric properties of La0.7 NdxBa(0.3-x)MnO3 (x = 0, 0.05, 0.1) were investigated.•The TC decreases with increasing Nd substitution and equals to 293 K for x = 0.05.•(−ΔSM)Max values are 2.7, 3.9, 3.9 J/kgK at 5 T for x = 0, 0.05, 0.1, respectively.•ΔTad was determined by using the Cp(T,H) and M(T,H) curves as 2.4 K at 5T.
The structural, magnetic and magnetocaloric properties of HoNi2 melt-spun ribbons were investigated by X-ray diffraction, magnetization and specific heat measurements. The as-solidified ribbons ...samples produced are single phase with the cubic MgCu2-type crystal structure of the Laves phase (C15; space group Fd-3m), and a Curie temperature TC of 13.9 K. For a magnetic field change μoΔH of 5 T (2 T) applied along the ribbon length, the produced ribbon samples show a maximum magnetic entropy change ΔSMpeak of −27.2 (−16.9) J kg−1 K−1, a full-width at half-maximum δTFWHM for the ΔSM(T) curve of 19 (11) K, and a refrigerant capacity, determined from the area below δTFWHM the ΔSM(T) curve, of 388 (145) Jkg−1; the adiabatic temperature change ΔTad at 2 T is 6.7 K. Whereas crystal structure and intrinsic magnetic properties are in good agreement with the experimental data previously reported in literature for bulk polycrystalline alloys, the magnetocaloric parameters at 2 T are markedly superior owing to the favorable combination of partial texture with the anisotropic behavior of magnetization.
•Single-phase ribbon flakes of HoNi2 were fabricated by melt spinning technique.•Structural, magnetic and magnetocaloric properties of HoNi2 melt-spun ribbons are reported.•MCE of HoNi2 melt-spun ribbons was studied by magnetization and heat capacity measurements.•At 2 T, ribbons show larger ∣ΔSMpeak∣ and ΔTadmax values with respect to bulk alloys.
We report the magnetic and magnetocaloric properties of rapidly solidified Ni0.895Cr0.105MnGe1.05 melt-spun ribbons studied by both direct (adiabatic temperature change) and indirect (isothermal ...magnetic entropy change) methods in intermediate and high magnetic fields up to 10 T. The maximum values of the adiabatic temperature changes (ΔTad) and magnetic entropy changes ( Δ S M ) were found to be ~2.6 K (µoH = 10 T) and 4.4 J kg-1 K-1 (µoΔH = 5 T), respectively, near the Curie temperature (TC). The ΔTad curves and magnetization isotherms were found to be completely reversible, which indicates the high degree of reversibility of the MCEs in this system. A large temperature span (of about 61 K) and a non-saturating behavior of ΔTad were observed at magnetic fields up to 10 T. The adiabatic temperature change was found to be a linear function of (µoH)2/3 near TC, in accordance with the Landau theory of phase transitions.
Magnetocaloric effect in ErNi2 melt-spun ribbons Sánchez Llamazares, J.L.; Ibarra-Gaytán, P.; Sánchez-Valdés, C.F. ...
Journal of rare earths,
June 2020, 2020-06-00, Volume:
38, Issue:
6
Journal Article
Peer reviewed
Open access
ErNi2 ribbons were produced by rapid solidification using the melt spinning technique. Their structural, magnetic and magnetocaloric properties in the as-solidified state were studied by X-ray ...diffraction, scanning electron microscopy, magnetization and specific heat measurements. Samples are single phase with the MgCu2-type crystal structure, a Curie temperature TC of 6.8 K and a saturation magnetization at 2 K and 5 T of 124.0 A⋅m2/kg. For a magnetic field change μ0ΔH of 5 T (2 T) ribbons show a maximum magnetic entropy change |ΔSMpeak| of 24.1 (16.9) J/(kg⋅K), and an adiabatic temperature change ΔTadmax of 8.1 (4.4) K; this is similar to the previously reported literature for bulk alloys that were processed through conventional melting techniques followed by prolonged thermal annealing. In addition, the samples also show slightly wider ΔSM(T) curves with respect to bulk alloys leading to a larger refrigerant capacity.
As-solidified isotropic melt-spun ribbons of the ErNi2 Laves phase show excellent magnetocaloric properties. Display omitted
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•Co51Fe1V33Ga15 Heusler alloy with large lattice entropy change is successfully fabricated.•Giant baro-caloric effect induced by low hydrostatic pressure near room temperature is ...obtained.•The ΔTadMax/Δpvalue in this work surpasses those values reported hitherto in baro-caloric alloys.•V-rich particles with the submicron scale are observed, which are believed to account for enhancing mechanical properties.•Co-Fe-V-Ga system is promising in the applications of solid-state refrigeration and heat pump.
Solid-state refrigeration based on the magneto- or mechano-caloric effect, including elasto- and baro-caloric in ferroic phase transition materials is promising to replace the current vapor compression refrigeration in consideration of environmental-friendliness and energy-saving. However, both high driven field and small thermal changes in all of these caloric materials hinder the development of solid-state refrigeration. Here we report a giant baro-caloric effect near room temperature induced by a low hydrostatic pressure in Co-based Co51Fe1V33Ga15 Heusler alloy. The maximum adiabatic temperature change under the applied pressure change of Δp = 0.1–100 MPa can be as high as ΔTadMax= 7.7 K (ΔTadMax/Δpreaches up to ∼7.7 K kbar−1), surpassing the ΔTadMax/Δpvalue reported hitherto in baro-caloric alloys. In addition, the microstructure is also studied by using the electron microscopes. Along with the austenite and martensite, the submicron V-rich particles are precipitated in this alloy, which are believed to account for enhancing mechanical properties.
The effect of arc melting and melt-spinning on magnetocaloric effect related magnetic properties of Ni43Mn46Sn11 alloys has been contrastively studied. Different measurements based on isothermal ...magnetization and heat capacity were carried out. For ribbon sample, extremely high magnetic entropy change ΔSM of 41.4Jkg−1K−1 and adiabatic temperature change ΔTad of 3.5K (0–5T) were achieved, which increases by 40.3% and 16.7% compared with that of bulk sample respectively. The martensitic transition related magnetic properties have been systematically discussed.
We report here the magnetic interactions, magnetocaloric effect and thermodynamic parameters of an efficient magnetic refrigerant material, Gd2GeO5, through magnetization and heat capacity ...measurements, as well as a mean-field and scaling analysis approach. An isotropic antiferromagnetic exchange coupling with energy scale εex = JexS2 ≈ 2.6 K is estimated from analysing the magnetization dependences, in agreement with the couplings derived from the density functional theory (DFT). The Gd2GeO5 shows an exceptionally large isothermal magnetic entropy change of 0.36 J K−1 cm−3 (50.3 J K−1 kg−1) and relative cooling power of 4.34 J cm−3 (611.3 J kg−1) for a field change of 8.9 T, with the highest adiabatic temperature change being 22.2 K, which is quite impressive for use in helium-free magnetic cryocoolers.
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The study of multicaloric effects in Heusler alloys has attracted increasing research interest, fueled by their potential applications in solid-state refrigeration and energy conversion technologies. ...Despite the promising aspects, challenges such as the limited operating temperature range and large hysteresis have hindered the optimal device performance. Herein, by introducing a Cu/Sn co-substitution strategy, a Curie temperature window for synergic magnetostructural transformation is extended from 244 K to 313 K in the customized NiMnCuGaSn alloys, along with a substantial increase in transformation entropy change. Crucially, employing a combined approach of magnetic-field-stress loading and zero-field-stress unloading significantly reduces stress hysteresis and enhances the reversibility of the transformation, resulting in a significant adiabatic temperature change of 4.7 K at a relatively low critical stress. This approach underscores an efficient method to enhance caloric responses, paving the way for advances in cooling technologies.
Gd-based amorphous alloys with excellent glass forming ability (GFA) exhibit outstanding magnetocaloric effect (MCE) at low temperature, but their GFA and MCE decrease dramatically with the ...increasing Curie temperature (Tc). In order to develop MCE materials suitable for room temperature refrigeration, it is urgent to further explore Gd-based amorphous alloys with enhanced MCE at or above room temperature. In this work, Tc of the Gd50Co50 amorphous alloy was successfully improved to room temperature by 2% (at. %) Fe substitution for Gd, accompanied with the enhanced GFA of the binary amorphous alloy. The maximum adiabatic temperature change of the Gd48Co50Fe2 amorphous alloy is at least 65% higher than those of the other metallic glasses at temperatures higher than 290 K. The results indicate that the Gd48Co50Fe2 amorphous alloy is a better candidate for magnetic refrigerant at room temperature.
•The GFA of the Gd50Co50 amorphous alloy was obviously improved by 2% (at. %) Fe substitution for Gd.•Tc of the Gd50Co50 amorphous alloy was successfully improved to room temperature by 2% (at. %) Fe substitution for Gd.•The maximum ΔTad of the Gd48Co50Fe2 ribbon is almost the highest in amorphous alloys at or above room temperatures.
•Direct and Indirect measurements of MCE in Ni0.895Cr0.105MnGe1.05 ribbons.•Reversible MCE with ΔTadmax ∼2.6 K and ΔSMpeak = −4.4 Jkg−1K−1 value near TC.•Large temperature span (∼61 K) and a ...non-saturating behavior of ΔTad at µoΔH = 10 T.
We report the magnetic and magnetocaloric properties of rapidly solidified Ni0.895Cr0.105MnGe1.05 melt-spun ribbons studied by both direct (adiabatic temperature change) and indirect (isothermal magnetic entropy change) methods in intermediate and high magnetic fields up to 10 T. The maximum values of the adiabatic temperature changes (ΔTad) and magnetic entropy changes (ΔSM) were found to be ∼2.6 K (µoH = 10 T) and 4.4 J kg−1 K−1 (µoΔH = 5 T), respectively, near the Curie temperature (TC). The ΔTad curves and magnetization isotherms were found to be completely reversible, which indicates the high degree of reversibility of the MCEs in this system. A large temperature span (of about 61 K) and a non-saturating behavior of ΔTad were observed at magnetic fields up to 10 T. The adiabatic temperature change was found to be a linear function of (µoH)2/3 near TC, in accordance with the Landau theory of phase transitions.
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