The recent literature concerning the magnetocaloric effect (MCE) has been reviewed. The MCE properties have been compiled and correlations have been made comparing the behaviours of the different families of magnetic materials which exhibit large or unusual MCE values. These families include: the lanthanide (R) Laves phases (RM2, where M = Al, Co and Ni), Gd5(Si1−xGex)4 ,M n(As1−xSbx), MnFe(P1−xAsx), La(Fe13−xSix) and their hydrides and the manganites (R1−xMxMnO3, where R = lanthanide and M = Ca, Sr and Ba). The potential for use of these materials in magnetic refrigeration is discussed, including a comparison with Gd as a near room temperature active magnetic regenerator material. (Some figures in this article are in colour only in the electronic version)

https://iopscience.iop.org/article/10.1088/0034-4885/68/6/R04/pdf

Recent developments in magnetocaloric materials

Review of the magnetocaloric effect in manganite materials

Giant and isotropic magnetoresistance as huge as −53% was observed in magnetic manganese oxide La0.72Ca0.25MnOz films with an intrinsic antiferromagnetic spin structure. We ascribe this magnetoresistance to spin‐dependent electron scattering due to spin canting of the manganese oxide.

31p-S-4 Giant Magnetoresistance in Magnetic Manganese Oxide with Intrinsic Antiferromagnetic Spin Structure

This letter reports on the superior magnetocaloric properties of La0.7Ca0.3−xSrxMnO3 (x=0.05, 0.10, 0.20, and 0.25) single crystals. Upon 50 kOe applied field, the magnetic entropy changes (ΔSM) reach values of ∼10.5, 7.45, 6.97, and 6.86J∕kgK for x=0.05, 0.10, 0.20, and 0.25 compositions, respectively. The large magnetic entropy changes have been found to occur around 300 K, thus allowing magnetic refrigeration at room temperature. Due to the absence of grains in the single crystals, the ΔSM distribution here is much more uniform than that of gadolinium and polycrystalline manganites, which is desirable for an Ericson-cycle magnetic refrigerator. The single crystals have the large magnetic entropy changes induced by low magnetic field change, which is beneficial for the household application of active magnetic refrigerant (AMR) materials. These results indicate that the present single crystals are excellent candidates as working materials for AMR.

Excellent magnetocaloric properties of La0.7Ca0.3−xSrxMnO3(0.05⩽x⩽0.25) single crystals

Combined rejected and naturally available heat constitute an enormous energy resource that remains mostly untapped. Thermal energy harvesting can provide a cost-effective and reliable way to convert available heat into mechanical motion or electricity. This extensive review analyzes the literature covering broad topical areas under solid-state low temperature thermal energy harvesting. These topics include thermoelectricity, pyroelectricity, thermomagneticity, and thermoelasticity. For each topical area, a detailed discussion is provided comprising of basic physics, working principle, performance characteristics, state-of-the-art materials, and current generation devices. Technical advancements reported in the literature are utilized to analyze the performance, identify the challenges, and provide guidance for material and mechanism selection. The review provides a detailed analysis of advantages and disadvantages of each energy harvesting mechanism, which will provide guidance towards designing a hybrid thermal energy harvester that can overcome various limitations of the individual mechanism.

A Review on low-grade thermal energy harvesting: Materials, methods and devices

Magnetic and magnetocaloric properties of La0.7Ca0.3−xBaxMnO3 compounds

Large magnetic-entropy change above 300 K in CMR materials

A large entropy change in a single crystal of La0.7Ca0.3MnO3, which undergoes a first-order ferromagnetic to paramagnetic transition at 227 K, was observed. As a result of a sharp drop in magnetization associated with ferromagnetic-paramagnetic transition, the magnetic entropy change, ΔSM, reaches a maximum value of about 6.42 J/kg K for an applied field of 5 T. The ΔSM distribution here is much more uniform than that of pure Gd metal, which is desirable for an Ericson-cycle magnetic refrigerator. Through these results, the La0.7Ca0.3MnO3 single crystal is strongly recommended to use as an active magnetic refrigerant for magnetic refrigerators.

Sheng-Bo Tian

Papers

Magnetic and magnetocaloric properties of La0.7Ca0.3−xBaxMnO3 compounds

Large magnetic-entropy change above 300 K in CMR materials

Magnetocaloric effect in a La0.7Ca0.3MnO3 single crystal

In situ growth of UiO-66-NH2 in wood-derived cellulose for iodine adsorption.