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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]

Perovskite MAPbBr3 (MA = CH3NH3+) single crystals were grown via the anti-solvent vapor-assisted crystallization method. The crystal growth process was optimized by adjusting the solution concentration and diluting the anti-solvent. The maximum size of the obtained crystal was 9 × 9 × 3 mm3. It shows that the MAPbBr3 single crystal is a cubic structure, the space group is Pm 3 ¯ m, and the lattice constant is 0.59062 nm. Furthermore, its energy band gap is approximately 2.23 eV. The atomic force microscopy results demonstrated that the growth process of MAPbBr3 single crystal followed the defect step growth mechanism, which was controlled by the screw dislocations within the crystal. Based on the curling growth of a screw dislocation on the crystal surface, a spiral step was formed. After the step was rotated around the entire mesa, a higher step was generated. Repeatedly, the step growth of screw dislocation within the crystal came into being. Besides, some small pits were also observed on (100) plane of the MAPbBr3 crystal. These pits hindered the movement of steps and affected the lattice arrangement around them, causing the structural mismatch and more defects within the crystals. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC) was used to investigate the thermal behavior and non-isothermal crystallization kinetics of the Fe67Nb5B28 metallic glasses prepared by melt-spinning method. DSC traces exhibit that the crystallization takes place through a single exothermic reaction, and it processes a good thermal stability in thermodynamics. The activation energies for nucleation and grain growth processes were calculated to be 536 ± 22 and 559 ± 20 kJ mol−1 by Kissinger equation, respectively, and 551 ± 24 and 574 ± 20 kJ mol−1 by Ozawa equation, respectively. It means that the grain growth process is more difficult than the nucleation process. The variation of local Avrami exponent n(x) with crystallized fraction x demonstrates that the crystallization mechanism varies at different stages. The n(x) is larger than 2.5 at the initial stage of 0 < x < 0.3, implying a mechanism of diffusion-controlled three-dimensional growth with increasing nucleation rate. The n(x) decreases from 2.5 to 1.5 in the range of 0.3 < x < 0.65, suggesting that the crystallization belongs to three-dimensional nucleation and grain growth with decreasing nucleation rate. And n(x) lies between 1.0 and 1.5 in the range of 0.65 < x < 0.95, indicating that the crystallization corresponds to the growth of particles with an appreciable initial volume. Low-temperature annealing corresponds to the precipitation of α-Fe, Fe2B, and Fe23B6 phases, and further annealing leads to the formation of α-Fe, Fe2B, and FeNbB phases. The magnetic properties in relation to microstructure change of the Fe67Nb5B28 metallic glasses are discussed. [ABSTRACT FROM AUTHOR]

We investigated the distribution of microscopic defects in an Al-doped CdZnTe crystal (CdZnTe:Al), grown under Cd-rich condition by the modified vertical Bridgman method, and their influence on the electrical transport behaviors. These microscopic defects were characterized by photoluminescence (PL), thermally stimulated current spectroscopy and thermoelectric effect spectroscopy. The results show that a low intensity and wide FWHM of (D, X) peak observed in the low-temperature PL spectrum of CdZnTe:Al sample implies the non-ideal high crystal quality, which is in good agreement with its results of electrical transport properties. The bulk resistivity of CdZnTe:Al sample was evaluated to be in the magnitude of 10 Ω cm with I-V and Hall measurements. Simultaneously, high leakage currents were observed to produce the high noise, which deteriorated the detection performance. Besides, the shallow donor Al with the activation energy of 13 meV and the relatively shallow acceptor A-center complex (V-Al) of 112 meV were identified to dominate the low- and high-temperature quenching processes in the temperature-dependent PL spectra, respectively. These microscopic defects as trapping or recombination centers for the charge carriers in CdZnTe:Al detector are responsible for its electrical transport properties, leading to the incomplete charge collection. A further comprehensive investigation on the distribution of microscopic defects was proved to achieve the balance between acceptors and donors in the defects compensation process of CdZnTe:Al sample. In particular, the E level at E − 0.554 eV was attributed to the doubly ionized Cd interstitial (Cd), which pinned the E level near the mid-gap to achieve the high resistivity performance. [ABSTRACT FROM AUTHOR]

The accelerated crucible rotation technique has been applied in the traveling heater method process for the growth of CdZnTe:In (CZT:In) ingots. Full single crystalline wafers with a diameter of 53 mm were obtained under optimized growth conditions. The crystalline quality and the photoelectric properties of the CZT crystals were characterized using infrared transmission microscopy, infrared transmittance spectra, current-voltage (I-V) analysis and gamma ray radiation response measurements. The CZT crystals show no Te inclusions over 3 μm in size and those smaller than 3 μm have a density of 10 cm. The resistivity of the crystals reaches 3.92 × 10 Ω/cm by fitting the I-V curve. The mobility-lifetime ( μτ) product of the electrons is 4.12 × 10 cm/V. Based on the CZT crystals, planar configuration and quasi-hemispherical configuration detectors were fabricated and show a resolution of 3.67% at Am@59.5 keV and 1.95% at Cs@662 keV, respectively, which indicates a superior detection performance. [ABSTRACT FROM AUTHOR]

A radiation damage mechanism of CdZnTe:In crystals under 60Co γ-rays with a cumulated radiation dose of ~2.4 kGy was proposed and discussed. Thermally stimulated current (TSC) measurements were carried out to characterize the γ-ray induced radiation damage. Four main trap levels (T1–T4) originating at four main microscopic defective states were identified. We attributed traps T1 and T2 to shallow donor impurities and shallow acceptor A-centers, respectively. Trap T3 was ascribed to dislocations and a great increase in defect concentration occurred after radiation. Trap T4 originated at deep acceptor Cd vacancies and vacancy related defect complexes and a considerable increase in the trap density, after radiation, lead to the conversion of conduction type from n to p in the Hall measurements and a Fermi level shift in the temperature-dependent resistivity analyses. Radiation induced electrically active defects contributed to the variation of the electrical compensation conditions and the worsening of the charge transport properties, which were consequently reflected by a significant deterioration in CZT detector performance. [ABSTRACT FROM AUTHOR]

Abstract: Defects exhibiting trapping behaviors in semi-insulating (SI) materials were investigated by thermally stimulated current (TSC) spectroscopy. The variation of measurement conditions during the initial photoexcitation and thermal emission, such as the heating rate, bias voltage, illumination time and delay time, may bring some significant effects on TSC spectra, leading to incomplete characterization of trap levels. In this work, defects with deep levels in the band gap of SI-Cd0.9Zn0.1Te crystal, grown by the modified vertical Bridgman (MVB) method, were studied via TSC measurements. TSC measurement of the SI-CZT sample was performed with the optimized measurement conditions. Ten different traps and a deep donor (E DD) level were characterized from the as-obtained spectrum in the temperature range from 25 to 310K with the aid of simultaneous multiple peak analysis (SIMPA). The origins of these traps were identified in detail as well. [Copyright &y& Elsevier]