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

Abstract

Perovskite manganite La 0.5 Ca 0.5-x □ x MnO 3 (LCMO) nanomaterials were elaborated using the sucrose modified auto combustion method. Rietveld refinements of the X-ray diffraction patterns of the crystalline structure confirm a single-phase orthorhombic state with Pbnm space group (No. 62). The Ca-vacancies were voluntarily created in the LCMO structure in order to study their influence on the magnetic behaviour in the system. The magnetic susceptibility was found to be highly enhanced in the sample with Ca-vacancies.Paramagnetic-to-ferromagnetic phase transition was evidenced in both samples around 254 K.This transition is, characterized by a drastic jump of the susceptibility in the sample with Cavacancies. The maximum of entropy change, observed for both compounds at magnetic field of 6T was 2.30 J kg -1 K -1 and 2.70 J kg -1 K -1 for the parent compound and the lacunar one respectively. The magnetocaloric adiabatic temperature change value calculated by indirect method was 5.6 K and 5.2 K for the non-lacunar and Ca-vacancy compound, respectively.The Ca-lacunar La 0.5 Ca 0.5-x □ x MnO 3 (x=0.05) reported in this work demonstrated overall enhancement of the magnetocaloric effect over the LCMO. The technique used to elaborate LCMO materials was beneficial to enhance the magnetocaloric effect and magnetic behaviour. Therefore, we conclude that this less costly environmentally friendly system can be considered as more advantageous candidate for magnetic refrigeration applications then the commonly Gd-based compounds.

Enhanced Relative cooling Power and large inverse magnetocaloric effect of cobalt ferrite nanoparticles synthesized by auto-combustion method

“…As it can be seen, the saturation of magnetization is attained even at 20 kOe, hence all the spins are oriented in parallel beyond this magnetic field value. At room temperature (300K), CFO sample represents a saturation of magnetization Ms of 83 emu/g that decreases with the increase of temperature and completely disappears at T>Tc, this behavior indicates the appearance of paramagnetic character [5], [39]. Note that, Ms, remnant magnetization (Mr) and coercive field (Hc) decrease as the temperature increases, being equal to zero at close to Tc.…”

“…In the literature, several classes of magnetic materials displayed a magnetocaloric effect including perovskite manganites, manganite alloys and spinel ferrites. Recently, the perovskite manganite La0.5Ca0.5−x□xMnO3(LCMO) exhibiting an interesting MCE, with a ΔT of 5.6 K is reported [5]. Meanwhile, in several researches, spinel ferrites with a second order magnetic transition have been shown to be effective instruments for magnetic refrigeration (MR) applications.…”

Impact of synthesis route on structural, magnetic, magnetocaloric and critical behavior of Nd0.6Sr0.4MnO3manganite

“…In this process ( Fig. 1a), 49,50 the nitrate reagents, Nd(NO 3 )$6H 2 O, Sr(NO 3 ) 2 , and Mn(NO 3 ) 2 $6H 2 O, were dissolved in distilled water, and the solution was kept under magnetic stirring for 1 h and heated on a hot plate at about 100 C until the mixture turned into a transparent and homogenous solution. The chelating agent used was glycine (C 2 H 5 NO 2 ), which was added at a molar ratio of 1 : 1 (nitrate : glycine).…”

Large Electrocaloric Responsivity and Energy Storage Response in the Lead-Free Ba(GexTi1−x)O3 Ceramics

“…Electrocaloric effect (ECE) is similar to magnetocaloric effect (MCE), in which the temperature change of the material is achieved by the electrical and magnetic field control, respectively [ 1 , 2 , 3 ]. Therefore, ECE occurs in switchable dipolar materials, where the application of electric field leads to change in the reversible polarization and consequently in the entropy [ 4 ].…”