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Due to the low toxicity and abundance of nature, Cu 2 ZnSn(S,Se) 4 (CZTSSe) has been considered as a promising solar cell material. The absorber is the most critical structure in a solar cell, which determines the performance of the cell. Selenium-rich CZTSSe can be formed by replacing S atoms of CZTS with Se. However, the method of adding Se element through H 2 Se is constrained due to the toxicity of H 2 Se. The work adopted a method to prepare excellent CZTSSe absorbers without H 2 Se. The stack structure CZTS precursor films were prepared by solution-based deposition, and CZTSSe absorbers were obtained after selenization annealing at 550 °C with 0.1, 0.2 and 0.3 g of selenium powders in argon, respectively. The obtained CZTSSe absorbers had pure CZTSSe phase, high absorption coefficients and appropriate bandgaps. After annealing with 0.2 g of selenium powder, the holes in the CZTSSe film diminished, and the grain size of absorbers increased from 0.31 µm in the CZTS absorber to 1.17 µm. The peaks of Se 3d for CZTSSe absorber were observed, the lattice spacing of plane (112) increased from 3.10 Å to 3.22 Å, and the work function decreased from 5.31 eV to 5.19 eV. The improved performance of absorber will be of great significance for the efficiency of CZTSSe device. • The CZTS precursor films were obtained by solution-based deposition. • The CZTSSe absorbers were obtained after selenization annealing with selenium powder in argon. • The grain size of the CZTSSe absorbers increased to the micron level. • The obtained CZTSSe absorbers had high absorption coefficients and appropriate band gaps. • The lattice spacing of plane (112) for CZTSSe absorber increased and the work function decreased. [ABSTRACT FROM AUTHOR]

The selective site occupation may occur in high entropy spinel oxide (HESO), which is essential for the structural and thermal stability. A single-phase (Co 0.2 Cr 0.2 Fe 0.2 Mn 0.2 Ni 0.2) 3 O 4 was therefore investigated to reveal its high stability in a wide temperature from room temperature to 1400°C in air/nitrogen. Characteristic features and DFT calculations proved the derived structural model, [Fe 0.5 Co 0.5 ]Td [Co 0.1 Fe 0.1 Cr 0.6 Mn 0.6 Ni 0.6 ]Oh O 4 , which highlighted the selective site occupation in HESO. The real structure presented here provides an alternate viewpoint on the cationic arrangement in HESO, which presented low crystal field stable energy value (−25.74 Dq) and low formation energy (−5.884 eV/atom). The HESO exhibited a low weight loss of 1.68 wt% at 1400 °C in nitrogen, which was 42.86 % lower than nickel ferrite spinel. No precipitation or decomposition was observed in the single-phase HESO in air. However, since the Gibbs free energy change of possible precipitation reactions of NiO and CoO oxides were negative below 1594 K, the precipitation of rock-salt phase close to (NiCo) 1-δ could be observed in nitrogen due to oxygen deficiency. • Valuable insights into the structure details of the (CoCrFeMnNi) 3 O 4 system. • Investigation of the phase stability of HESO at a wide range temperature. • The role of oxygen partial pressure in the entropy-driven phase transition. [ABSTRACT FROM AUTHOR]

Hot compression experiments of a Ti55511 titanium alloy are conducted to study the phase transformation characteristics and dynamic recrystallization (DRX) behavior. It is found that the fraction of α phase decreases with increasing the strain rate or deformation amount. Meanwhile, the original lamellar α phases easily transform into the spheroidal and bulk α phases at larger deformation amounts or higher strain rates. Most of α phases disappear and the final microstructures are mainly β phases when the temperature is over 800 °C. The DRX degree rises with raising the deformation amount or decreasing the strain rate. However, the DRX behavior becomes weaken with raising the deformation temperature. α phases are evenly distributed around β phases during hot compressive deformation, which not only restrains the growth of β phases but also promotes the DRX process of β phases. In addition, the geometric DRX takes place within α phases, while the continuous DRX occurs within β phases during the hot compression. Image 1 • Phase transformation and dynamic recrystallization (DRX) behavior of a Ti55511 titanium alloy are studied. • The volume fraction of α phase decreases with increasing the strain rate or deformation degree. • Initial lamellar α phases easily transforms into bulk/spheroidal α phases at the larger strains or higher strain rates. • The α phases not only restrains the growth of β phase, but also promotes the DRX process of β phase. • The geometric DRX takes place within α phases, while the continuous DRX occurs within β phases. [ABSTRACT FROM AUTHOR]

The α ↔ β phase transformation in dual-phase Ti–55531 alloy during the continuous heating was investigated by combining dilatometer test with microstructure characterization and local composition mapping. It was found that the α ↔ β phase transformation in individual temperature regions mainly involved either of two types of α phases, i.e. the lamellar α phase which forms during the continuous heating or the slab α phase raised in preliminary isothermal reaction. The corresponding transformation sequence was verified as β → α lamellae , α lamellae → β, and α slab → β. The pile-ups of alloying elements at the α/β interface were understood by either local equilibrium condition or differences among net diffusion fluxes of alloying elements. More important was that the growth and dissolution kinetics of both α phases were modeled and compared with experiments. With the calculations, the dissolution of slab α phase was demonstrated to follow the kinetics of planar interface without the Gibbs-Thomson effect. In contrast, the Gibbs-Thomson effect was proven to do contribution to lamellar α phase. It not only decreased the stability of α tip, such that the re-dissolution of lamellar α tips took place at 838 K below the equilibrium temperature, but also introduced a competition between the shrink of tips and thickening of broad face in α lamellae at 838–911 K. Moreover, the lengthening of lamellar α tips was proven to follow a kinetics controlled by a mixture of bulk and boundary diffusion, in comparison with the pure bulk diffusion of fastest Al governed the re-dissolution of both tips and broad faces. [ABSTRACT FROM AUTHOR]

• NiCuZn ferrite was fabricated through a simple approach. • The sintering temperature of the NiCuZn ferrite is reduced with the two-step sintering method. • The NiCuZn ferrite exhibits high permeability for the synergistic effect. Nickel-copper-zinc (NiCuZn) ferrites with high permeability and low magnetic loss have high application potential in high-frequency electronics. In this work, NiCuZn ferrite samples with different Cu contents were prepared by a two-step sintering method. First, the optimal temperatures of the two-step sintering method (1025/925 °C) were confirmed, thereafter the influence of the Cu content on the crystal structure, microstructure, magnetic and dielectric properties of NiCuZn ferrite were studied in detail. Structural characterization showed that an increase in Cu content promoted grain growth and resulted in NiCuZn ferrites with a denser microstructure and decreased porosity. However, a second phase of CuO formed once the content of Cu (x value) reached 0.16. The magnetic hysteresis loops revealed that the saturation magnetization increased as x increased and the highest value of 57.3 emu/g was obtained at x = 0.14. The dielectric property measurement showed that increasing the Cu content could improve the dielectric constant and reduce the dielectric loss. The permeability measurements showed an increase in permeability with Cu content from x = 0.10 to x = 0.14 and a decrease when x = 0.16. Consequently, a NiCuZn ferrite with an appropriate microstructure and with high permeability (μ'=855), low magnetic loss (tanδ μ = 0.02), and high saturation magnetization (57.3 emu/g) could be obtained at a Cu content of x = 0.14 and sintering temperatures of 1025/925 °C in the two-step sintering method. This NiCuZn ferrite provides new guidance for developing RF frequency multilayer inductors. [ABSTRACT FROM AUTHOR]

Abstract: The Zn0.95Co0.05O films were deposited under different oxygen partial pressure () by inductively coupled plasma enhanced physical vapor deposition. The effect of on the local structure of Zn0.95Co0.05O films was investigated by X-ray absorption spectroscopy (XAS) at Co K-edge and L-edge. The Co L-edge XAS spectra show the spin-orbit splitting and typical shake-up satellites of the Co2+ ionization states. The XAS spectra at the Co K-edge indicate that Co ions substitute for Zn2+ sites in the tetrahedral configuration without changing the wurtzite structure. The qualitative analyses of X-ray absorption near edge structure (XANES) reveal that the main defects are oxygen vacancies when Zn0.95Co0.05O films were deposited under very low . The extended X-ray absorption fine structure (EXAFS) analyses provide no significant bond length deviation from the pure ZnO structure. The coordination number varies slightly with different samples. The correlation between the coordination number and the pseudo Debye–Waller factor implies that the disorder is increased in samples prepared under low . [Copyright &y& Elsevier]

Unstable nanoparticles/carbonaceous nanomaterial synthesis results in inhomogeneous mass and charge transfer across the electrode/electrolyte interface. And high-entropy alloy nanoparticles (HEA-NPs) are rarely reported in supercapacitors. Herein, this study reports an uniform carbothermal shock (CTS) of quinary HEA-NPs on super aligned electrospun carbon nanofibers (ACNFs). The key to this approach is coupling a self-designed collector for aligned CNFs and a suitable CTS current direction. For the electrochemical performance, the FeNiCoMnMg HEA-NPs/ACNFs electrodes with 5 mM precursor concentration show a high capacitance of 203 F/g and a specific energy density of 21.7 Wh/kg. These findings give hints for the HEA-NPs/carbonaceous nanomaterials as promising candidates for energy storage applications. • The quinary FeNiCoMnMg and FeNiCoMuCu HEA-NPs were synthesized. • Super aligned electrospun carbon nanofibers were fabricated. • The transformation of bonding configuration and valence states of elements were investigated. • A high capacitance of 203 F/g was achieved by the FeNiCoMnMg HEA-NPs/ACNFs electrodes. [ABSTRACT FROM AUTHOR]