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Magnetic refrigeration (MR) technology possesses the potential to substitute conventional gas compression technology. It is necessary to find MR materials suitable for a variety of applications. In this study, La 0.65 Sr 0.35- x Eu x Mn 0.95 Ni 0.05 O 3 (x = 0.05, 0.075, 0.10) (LSE x MNO) ceramics were prepared using a sol-gel synthesis process. The LSE x MNO ceramics were confirmed to be the R ‾ 3c space group (rhombohedral structure) by X-ray diffraction (XRD) analysis. The particles of LSE x MNO ceramic particles were irregular polyhedral particles by Scanning electron microscopy (SEM). The chemical composition of LSE x MNO was determined by energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The Magnetic Property Measurement System (MPMS) demonstrated that the LSE x MNO ceramics display second-order magnetic phase transitions (SOMPT) around Curie temperature (T C). When the Eu3+ doping level increased, the Mn–O–Mn bond angle and length increased, weakening the exchange coupling of the Mn4+-O2--Mn3+ channel and decreasing the T C. As the amount of Eu3+ doping varied, the maximum magnetic entropy (– Δ S M Max) of the LSE x MNO ceramics peaked at 4.03 J kg−1K−1 and cooling efficiency parameter (RCP) = 291.2 J kg−1 at x = 0.075. The Modified Arrott plots (MAP) and Kouvel-Fisher (K–F) approaches were applied for the purpose of certifying the critical exponents of LSE 0.075 MNO ceramics conform to the Mean Filed model. Compared with other magnetic materials, it displays an excellent magnetocaloric effect (MCE) with a T C of 299 K. [ABSTRACT FROM AUTHOR]

The harmless disposal of lead paste in the spent lead-acid batteries (LABs) remains an enormous challenge in traditional pyrometallurgical recycling. Here, we introduced a hydrometallurgical method for the recycling of the spent LABs' waste to obtain the β -PbO as a novel zinc ion batteries (ZIBs) active material. The obtained β -PbO exhibits ultra-flat charge/discharge voltage platforms (0.21 mV/(mAh g−1)) and stable specific capacity. During the charge/discharge, the β -PbO spontaneously triggers the formation of (ZnSO 4)[Zn(OH) 2 ] 3 ·5H 2 O (ZHS) micro-sheets as a surface passivation layer. Moreover, the ex-situ X-ray spectra reveal that the reversible phase transformation occurs between PbSO 4 and Pb with the assistance of ZHS by adjusting the PH value on the electrode-electrolyte interface. The synergistic two-phase-reaction mechanism generates ultra-flat voltage platforms upon the charge/discharge. This "energy-saving and environment-friendly" recycling route eliminates the major source of emission of pollution particulates/gases compared to the traditional pyrometallurgical recycling, while at the same time replacing energy-consuming and environmentally detrimental processes of synthesis of current ZIBs cathodes. [ABSTRACT FROM AUTHOR]

The effects of K+ doping on structure, magnetic characteristics, magnetocaloric properties, and critical behavior of La 0.7-x Nd 0.1 Sr 0.2 K x Mn 0.95 Ni 0.05 O 3 (LNSKMNO) ceramics (x = 0.00, 0.05, and 0.10) were investigated. The X-ray diffraction and refinement findings revealed that LNSKMNO exhibited a distinctive rhombohedral structure of the R-3c space group (No. 167). To validate the chemical composition of LNSKMNO ceramics, EDS spectroscopy and X-ray photoelectron spectroscopy (XPS) were utilized. The magnetization of LNSKMNO exhibited a temperature-dependent behavior, revealing a phase transition from the ferromagnetic (FM) phase to the paramagnetic (PM) phase at approximately the Curie temperature (Tc). By utilizing normalization and Banerjee's criterion, the magnetic phase transition of LNSKMNO was determined to be a second order magnetic phase transition. The maximal magnetic entropy (− Δ S M max) of LNSKMNO around Tc was 4.24, 4.53, and 4.07 J/(kg K) at the 5 T external magnetic field (H). The Kouvel-Fisher approach and modified Arrott plot were used for determining the values of the critical exponents of β , γ , and δ. The critical exponents for LNSKMNO ceramics generally conformed to those obtained based on the Mean-field model. [ABSTRACT FROM AUTHOR]