Magnetic and magnetocaloric properties of La0.6Ca0.4MnO3 tunable by particle size and dimensionality

Abstract

Manganites have been attracted considerable attention due to some intriguing magnetic properties, such as magnetoresistance, spin glass behavior and superparamagnetism. In recent years, some studies point to the effect of particle size and dimensionality of these compounds in their magnetic features. Particularly, LaCaMnO material research is well explored concerning the bulk material. To overcome the lack of the information we successfully produced advanced nanostructures of La 0.6 Ca 0.4 MnO 3 manganites, namely nanotubes and nanoparticles by using a sol-gel modified method, to determine the size particle effect on the magnetism. The manganites crystal structure, magnetic and magnetocaloric properties were studied in a broad temperature range. Transmission electron microscopy revealed nanoparticles with sizes from 45 up to 223 nm, depending on the calcination temperature. It was found that the magnetic and magnetocaloric properties can be optimized by tuning the particle size; for instance, the magnetic transition broadening by decreasing the particle size. We report the relative cooling power (RCP) of these samples; it was found that the best RCP was observed for the 223 nm particle (508 J/Kg). Finally, this work contributes to the research on the magnetic properties and magnetocaloric potentials in nanostructured systems with distinct morphologies.

Synthesis of La0.5Ca0.5−x□xMnO3 nanocrystalline manganites by sucrose assisted auto combustion route and study of their structural, magnetic and magnetocaloric properties

“…Magnetic and electrical transitions as well as colossal magnetoresistance (CMR) have been studied previously in this system. In addition, their MCE gains interest due to their near room temperature large entropy change, 8.3 J kg -1 K -1 at 270 K under a magnetic field of 5 T, as reported by Andrade et al [24]. Moreover the manganites seem to be very promising MCE candidates, since their transition temperature and the magnitude of their ∆S M can be strongly modified by adjusting their chemical composition [25] and their microstructure according to the elaboration method and its conditions [26].…”

Distribution of Transition Temperatures in Magnetic Transformations: Sources, Effects and Procedures to Extract Information from Experimental Data

“…It is observed that the slope of change in martensitic transformation is several times larger than the change in the Curie temperature of the austenitic phase, T A C . In fact, as an example, whereas T A C is almost unaffected when composition changes from Ni 49 Magnetoelastic transition occurring for La(Fe,Si)13 phase is strongly dependent on the Si content [2,38,39]. Despite the order character of the transition (FOPT for low Si content and SOPT for high Si content [38]), an almost linear correlation is followed with this parameter (see Figure 3).…”

“…However, changes in the magnetization and Curie transition are theoretically limited to very few layers, approximately <10, in thin films [47]. Nanosized manganites show a broader transition [48] and even bulk antiferromagnetic manganites can be FM when crystal size is reduced to nanometer scale [49]. Reduction of crystal size from 90 to 38 nm in DyCuAl reduces T C from 27 to 24 K [50].…”

Freestanding and flexible composites of magnetocaloric Gd5(Si,Ge)4 microparticles embedded in thermoplastic poly(methyl methacrylate) matrix

“…At a first glance, one highlight is the broadening of the diffracted peaks on the used powder in comparison the bulk counterpart. This is a direct consequence on the reduction of particle size after sieving 11,28,29 . From Rietveld refinements it was found the formation of expected O(I) structure, M-phase and eutectic R 5 M 3 -phase (that will be simply denoted as 5:3) 25 , with the results summarized for all samples on Table I.…”