Impact of Annealing Temperature on the Physical Properties of the Lanthanum Deficiency Manganites

Abstract

Abstract:The lanthanum deficiency manganites La 0.8−x x Ca 0.2 MnO 3 (x = 0, 0.1 and 0.2), where is a lanthanum vacancy, were prepared using the classic ceramic methods with different thermal treatments (1373 K and 973 K). The structural, magnetic, and magnetocaloric properties of these compounds were studied as a function of annealing temperature. It was noted that the annealing temperature did not affect the crystal structure of our samples (orthorhombic structure with Pnma space group). Nevertheless, a change in the variation of the unit cell volume V, the average bond length d Mn-O , and the average bond angles θ Mn-O-Mn were observed. Magnetization versus temperature study has shown that all samples exhibited a magnetic transition from ferromagnetic (FM) to paramagnetic (PM) phase with increasing temperature. However, it can be clearly seen that the annealing at 973 K induced an increase of the magnetization. In addition, the magnetocaloric effect (MCE) as well as the relative cooling power (RCP) were estimated. As an important result, the values of MCE and RCP in our Lanthanum-deficiency manganites are reported to be near to those found in gadolinium, considered as magnetocaloric reference material.

Expansion of the multifunctionality in off-stoichiometric manganites using post-annealing and high pressure: physical and electrochemical studies

“…Moreover, as t ann increases, the grain size of LMO increases from 1.6 to 8.1 μm which is also observed for deficient manganites. 53,54…”

“…Moreover, as t ann increases, the grain size of LMO increases from 1.6 to 8.1 mm which is also observed for deficient manganites. 53,54 Additionally, XPS was used to define the surface elemental composition and valence state of the ions (Fig. 2 for Mn ions only and Fig.…”

Structural study and large magnetocaloric entropy change at room temperature of La1−x□xMnO3 compounds

“…The maximum values of DS M and RCP obtained at 2 T were compared to gadolinium Gd 45 as well as several other materials reported in literature. [46][47][48] The results are in favor of promising magnetic refrigerants in terms of application. The good value of RCP equal to 131.4 J kg À1 for x ¼ 0.1 is due to the strong magneto-structural coupling.…”

Enhanced Ferromagnetism Induced by Chemical Doping and Epitaxial Strain in La0.8Sr0.2CoO3 Films

“…In general, the thermal treatment process is crucial for the growth process and crystal quality of epitaxial films [18]. In this part, the studies about structural characteristics of LCO grown on (001) with different annealing temperatures were carried out to study the influence of annealing temperature on film quality.…”