Influence of heat sintering on the physical properties of bulk La_0.67Ca_0.33MnO₃ perovskite manganite: role of oxygen in tuning the magnetocaloric response

Abstract

The study explores the influence of oxygen stoichiometry on the physical properties of bulk La0.67Ca0.33MnO3 manganite.

Investigation of the impact of A-site cation disorder on the structure, magnetic properties, and magnetic entropy change of trisubstituted divalent ions in La0.7(Ba,Ca,Sr)0.3MnO3 manganite

“…O I and O II were designated as lattice oxygen owing to Mn–O and La/Ba/Ca/Sr–O bonding. 58,60 However, O III may arise because of the presence of oxygen vacancies attributed to the hydroxylation (OH) and carbon oxidation states (C–O). 58,60 The peak positions and area ratios of the O 1s fitted peaks are listed in Table 5.…”

“…48 Initially, similar O 1s spectra were observed for other perovskite manganites, with various interpretations and contradictions, referring to oxygen bonding with the various elements of the compound, defects and vacancies. [48][49][50][51][53][54][55][58][59][60][61] Based on several studies, the deconvolution of the O 1s spectra obtained for LBCS compounds segregates the contribution from the three different types of oxygen species as shown in Fig. 10.…”

“…10. These are denoted as O I , O II , and O III at peak positions 58,60 The peak positions and area ratios of the O 1s fitted peaks are listed in Table 5. The O III ratio indicates the concentration of oxygen vacancies at the particle surface, which is consistent with previous EDS results.…”

Functional LSMO foams for magneto-caloric applications

“…The calculation of RCP yields 112.8 J kg −1 for the LSMO foam and 88.2 J kg −1 for the LSMO bulk, being well in the range as shown in Refs. [6,7,50,51] and can be well compared to various metallic materials [52], but at higher temperatures well above room-temperature. Very remarkable is, however, the RCP value for the LSMO nanowire network with 111.2 J kg −1 , which is due to the very broad peak in | | ΔS M (T) | | .…”

“…The perovskite-type manganites (generic formula A 1−x B x MnO y ) offer several different functionalities, including the colossal magneto-resistance (CMR) [1], which is interesting for various sensor elements [2][3][4][5], and large magnetic entropy changes [6,7] at the Curie temperature, T C , being interesting e.g., for thermal storage as well as for magnetic refrigeration [8,9]. For magnetic refrigeration using the magneto-caloric effect (MCE), the manganites have to compete with several types of metallic compounds, see e.g., the reviews by Gschneidner et al [8], Gottschall et al [10] and Belo et al [11].…”