Magnetic and calorimetric measurements on the magnetocaloric effect in La0.6Ca0.4MnO3

Bohigas, Xavier; Tejada, J.; Marı́nez-Sarrión, M.L; Tripp, S.; Black, R. C.

doi:10.1016/s0304-8853(99)00581-8

Cited by 122 publications

(44 citation statements)

References 14 publications

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“…S M = −143 mJ/cm 3 K for Gd 5 (Si 2 Ge 2 ) (T C = 275K) and −538 mJ/cm 3 K for Gd 5 (SiGe 3 ) (T C = 140 K) for H = 5 T (see Table 1 From the known magnetic/structural/electronic (La 1−x Ca x )MnO 3 phase diagram (140), these compositions exhibit a ferromagnetic insulator/ferromagnetic metal transition for 0.18 ≤ x ≤ 0.28, or a ferromagnetic metal/paramagnetic insulator transition for 0.28 ≤ x ≤ 0.50, which probably accounts for their enhanced magnetocaloric properties. To date only one direct measurement of the adiabatic temperature change has been made (141). The T ad value of La 0.6 Ca 0.4 MnO 3 (2.1 K for a 3 T field change at T C = 260 K) was calculated from heat capacity measurements and is about what one might expect for the composition of this material and its S M relative to the other perovskite phases.…”

Section: Manganitesmentioning

confidence: 99%

Magnetocaloric Materials

Gschneidner

Pecharsky

2000

Annu. Rev. Mater. Sci.

1,208

555

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Key Words magnetocaloric effect, mixed lanthanide materials, 3d-materials amorphous alloys, manganites s Abstract In the last decade of the twentieth century there has been a significant increase in research on a more than 100-year old phenomenon-the magnetocaloric effect (MCE). As a result, many new materials with large MCEs (and many with lesser values) have been discovered, and a much better understanding of this magneto-thermal property has resulted. In this review we briefly discuss the principles of magnetic cooling (and heating); the measurement of the magnetocaloric properties by direct and indirect techniques; the special problems that can arise; and the MCE properties of the 4f lanthanide metals, their intra-lanthanide alloys and their compounds [including the giant MCE Gd 5 (Si x Ge 1−x ) 4 phases]; the 3d transition metals, their alloys and compounds; and mixed lanthanide-3d transition metal materials (including the La manganites). INTRODUCTIONCommercial and residential refrigeration is a mature, relatively low capital cost but a high-energy demand industry. Even the newest most efficient units operate well below the maximum theoretical (Carnot) efficiency, and few, if any, further improvements may be possible with the existing vapor-cycle technology. Magnetic refrigeration (MR), however, is rapidly becoming competitive with conventional gas compression technology because it offers considerable operating cost savings by eliminating the most inefficient part of the refrigerator-the compressor. In addition to its energy savings potential, MR is an environmentally sound alternative to vapor-cycle refrigerators and air conditioners. Most modern refrigeration systems and air conditioners still use ozone-depleting or global-warming volatile liquid refrigerants. Magnetic refrigerators use a solid refrigerant(s) and common heat transfer fluids (e.g. water, water-alcohol solution, air, or helium gas) with no ozone-depleting and/or global-warming effects.Magnetic refrigeration is based on the magnetocaloric effect (MCE). The MCE, or adiabatic temperature change ( T ad ), which is detected as the heating or the cooling of magnetic materials due to a varying magnetic field, was originally discovered in iron by Warburg (1). The thermodynamics of the MCE was understood 0084-6600/00/0801-0387$14.00 387 Annu. Rev. Mater. Sci. 2000.30:387-429. Downloaded from www.annualreviews.org by Fordham University on 11/22/12. For personal use only. 388GSCHNEIDNER PECHARSKY by Debye (2) and by Giauque (3), both of whom independently suggested that it could be used to reach low temperatures in a process known as adiabatic demagnetization. Soon after this discovery, an operating adiabatic demagnetization refrigerator was constructed and utilized by Giauque & McDougal (4) to reach 0.53, 0.34, and 0.25 K starting at 3.4, 2.0, and 1.5 K, respectively, using a magnetic field of 0.8 T and 61 g of Gd 2 (SO 4 ) 3 ·8H 2 O as the magnetic refrigerant. The MCE is intrinsic to any magnetic material. In the case of a ferromagnet near its mag...

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Section: Manganitesmentioning

confidence: 99%

Magnetocaloric Materials

Gschneidner

Pecharsky

2000

Annu. Rev. Mater. Sci.

1,208

555

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“…The equivalence of these two different methods has been demonstrated. 4,7 In an isothermal process of magnetization, the total magnetic entropy change of the system due to the application of a magnetic field, ⌬S B , can be derived from Maxwell relations by integrating over the magnetic field, i.e.,…”

mentioning

confidence: 99%

Magnetocaloric effect in random magnetic anisotropy materials

Bohigas

Tejada

Torres

et al. 2002

Applied Physics Letters

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In this letter we report the results of entropy variations in random anisotropy magnets composed of TbxY1−xAl2, with x=0.15, 0.20, 0.25, 0.35, 0.40, and 0.50. We discovered large entropy variation associated with the spin glass to paramagnetic transition. Both temperature transition and entropy changes were studied at different temperatures and with different compositions. Our conclusion is that these materials are suitable candidates for use as magnetic refrigerants in a temperature range below 40 K.

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“…For LBMO40 and LCMO40, Tc's of 312 K and 262 K respectively have been identified in keeping with the literature. 26,27 These low Tc's are in line with neither material exhibiting significant magnetic hyperthermia at room temperature.…”

Section: Magnetic Measurementsmentioning

confidence: 52%

Synthesis, characterisation and study of magnetocaloric effects (enhanced and reduced) in manganate perovskites

McBride

Partridge

Bennington-Gray

et al. 2017

Materials Research Bulletin

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Highlights• La1-xCaxMnO3 and La1-xBaxMnO3 synthesised using the modified peroxide sol-gel synthesis.• Enhanced magnetic heating for manganates doped with A-site cations larger than La 3+ .• Reduced magnetic heating observed for manganates doped with A-site cations smaller than La 3+ . 1 AbstractThe effect of the A-site dopant ionic radii on the observed magnetocaloric effect (MCE) exhibited by three different families of manganese-based perovskites was investigated using both induction heating and SQUID magnetometry measurements. The doped perovskites La1-xSrxMnO3 (LSMO), La1-xCaxMnO3 (LCMO), and La1-xBaxMnO3 (LBMO) (x = 0.25, 0.35, 0.4) were prepared using a modified peroxide sol-gel synthesis. This method has not been previously used for the synthesis of LCMO or LBMO. Structural characterisation of the agglomerates of magnetic nanoparticles (MNP) for each material was carried out using SEM, XRD and IR spectroscopy. Magnetic heating was observed for materials with larger A-site dopant radii relative to La 3+ ; LSMO40 and LBMO40, with average SARs obtained of 51.5 Wg -1 Mn and 33.8Wg -1 Mn respectively. However, reduced magnetic heating effects were observed for smaller A-site dopant radii relative to La 3+ (LCMO). In fact, the calculated Specific Absorption Rate for LCMO40 of 14.72 Wg -1 Mn is half that of the blank.

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Magnetic and calorimetric measurements on the magnetocaloric effect in La0.6Ca0.4MnO3

Cited by 122 publications

References 14 publications

Magnetocaloric Materials

Magnetocaloric Materials

Magnetocaloric effect in random magnetic anisotropy materials

Synthesis, characterisation and study of magnetocaloric effects (enhanced and reduced) in manganate perovskites

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