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In this study, we have synthesized a nanostructured core–shell framework of carbon-coated copper sulfide (C@CuS) through a one-step precipitation technique. The carbon sphere template facilitated the nucleation of CuS nanostructures. The synthesized nanocomposites have demonstrated remarkable lithium-ion storage capabilities when utilized as an anode in lithium-ion batteries. Notably, they exhibit an impressive rate capability of 314 mAh g−1 at a high current density of 5000 mA g−1, along with excellent long-term cycle stability, maintaining 463 mAh g−1 at 1000 mA g−1 after 800 cycles. This superior performance is due to the core–shell architecture of the composite, where the carbon core enhances the conductivity of CuS nanoparticles and mitigates volume expansion, thus preventing capacity loss. Our study not only elucidates the significance of carbon in the construction of nano-heterojunctions or composite electrodes but also presents a practical approach to significantly boost the electrochemical performance of CuS and other metal sulfides. [ABSTRACT FROM AUTHOR]

In this study, we synthesized spinel high-entropy oxide (HEO) (Cr0.2Mn0.2Co0.2Ni0.2Zn0.2)3O4 nanoparticles by a simple solution combustion method. These particles were investigated for their performance as anodes in lithium-ion batteries. The reversible capacity is 132 mAh·g−1 after 100 cycles at a current density of 100 mA·g−1, 107 mAh·g−1 after 1000 cycles at a current density of 1 A g−1, and 96 mAh·g−1 rate capacity at a high current density of 2 A g−1. The outstanding cycle stability under high current densities and remarkable rate performance can be attributed to the stable structure originating from the high entropy of the material. [ABSTRACT FROM AUTHOR]

This study was conducted to understand the nature of the polar state in the morphotropic phase boundary composition 0.67BiFeO3–0.33BaTiO3 (0.67BF–0.33BT). Both the unpoled and poled specimens exhibit an average cubic structure. The poling induces a 0.14% increase in the lattice parameter. Macrodomains are absent both in the initial and polar state of 0.67BF–0.33BT. A typical relaxor-type dielectric anomaly was observed (Tf = ~ 627 K, TB = ~ 820 K). The remnant polarization (Pr), maximum value of electrostrain (Sm), and magnitude strain at Ec in the bipolar mode (Sneg) increase clearly during heating (Pr, ~ 40 µC/cm2; Sm, 0.191% under 40 kV/cm at 453 K). Unlike Bi0.5Na0.5TiO3-based nonergodic relaxors, the first-cycle bipolar electrostrain loops indicate that the minimum strain on the negative side of the bipolar strain curves is negative. Furthermore, the slopes of the relative permittivity versus log frequency plots in unpoled (− 21) and poled (− 23) specimens are similar. The transition between the relaxor state and ferroelectric-like state does not involve a clear dielectric anomaly even in the poled specimen. [ABSTRACT FROM AUTHOR]

Lead-free BiFeO3 ceramics doped with varying amounts of Bi2O3–B2O3–ZnO (BBZ) glass, that is, x wt% (x = 0.0, 0.5, 1.0, 1.5, and 2.0) were prepared via the traditional solid-state reaction route. The effects of BBZ glass content on the phase composition, microstructure, dielectric, and ferroelectric properties of BiFeO3 ceramics were investigated. X-ray diffraction results confirmed that BBZ glass doping increased the formation of secondary phases (Bi2Fe4O9 and Bi25FeO39). Scanning electron microscopy images showed that the samples with the addition of BBZ glass showed a heterogeneous size distribution of grains and more porosity. With the increase of the BBZ glass content, the fluctuation of Fe-ions was decreased and the bond strength of the Bi-O was increased. The samples with BBZ glass addition showed smaller dielectric constant and more saturated polarization hysteresis loops compared with pure BiFeO3. The Curie temperature (TC) decreased gradually from 825.8 °C for x = 0.0 to 637.0 °C for x = 2.0. In addition, leakage current density decreased with the addition of BBZ glass. These changes of the electric properties were related to the heterogeneous size distribution of grains, the generation of secondary phases and the increase of the concentration ratios of Fe3+ and Fe2+ in BiFeO3-xBBZ samples. [ABSTRACT FROM AUTHOR]