Bulletin of Materials Science最新文献

The green energy storage of polyaniline, without major wastages excreted into the environment is effectively demonstrated by using the polyaniline as supercapacitor electrode and the by-product obtained during the synthesis of polyaniline as its electrolyte. This green approach to the energy storage properties of sulphuric acid doped polyaniline (H-PANI) exhibited a substantial improvement in its energy storage, compared to the conventional approach of using an ionically conducting liquid as electrolyte like 1 M H₂SO₄ (SA), separately. The amelioration of 40.44% was achieved when the by-product obtained as supernatant liquid (SL) was used as electrolyte compared to SA. The H-PANI provided a specific capacity (Q) of 146.4 C g⁻¹, a specific energy (E) of 24.40 W h kg⁻¹ and a specific power (P) of 1.200 kW kg⁻¹ at 1 A g⁻¹ in the presence of SA. The Q of 205.6 C g⁻¹, E of 34.26 W h kg⁻¹ (similar range of E of Pb-acid batteries), P of 1.200 kW kg⁻¹ were achieved in the presence of SL at 1 A g⁻¹ and a high rate capability of 29.18% retention of initial Q up to 25 A g⁻¹ was also achieved. This approach is useful to harvest high energy characters from PANI.

Lead-free glasses of composition, (ZnO)_0.3–(V₂O₅)_0.3-x–(B₂O₃)_0.4–(La₂O₃)_x; x = 0.01–0.05 were made by melt-quenching procedure. Their amorphous nature was established. FTIR studies revealed that functional groups are present in the glasses. Band (indirect) gaps obtained from UV–Vis absorption spectra, increased with increase in La₂O₃ content from 2.505 to 2.828 eV. Urbach energy and refractive index were decreased from 0.397 to 0.292 eV and 2.544–2.440, respectively, with La₂O₃. Various optical parameters have been estimated. These suggest the suitability of these glasses for photoelectronic applications. Using Phy-X/PSD and XCOM softwares, gamma- and neutron-shielding parameters were evaluated for photon energy range of 0.15–15 MeV. Mass and linear attenuation coefficients were found to increase with increase in La₂O₃ mole fractions. Minimum half value and tenth value layers (HVL, TVL) of the glasses at 0.015 MeV, are found to lie between 0.007 and 0.006 cm, and 0.0260 and 0.0211 cm, respectively. Maximum exposure build-up factors (EBF) at 0.4 MeV for 40 mean free path (MFP) were found in the range of 199.37–110.26 and energy absorption build-up factors (EABF) in the range of 407.98–220.11. Removal cross-sections for fast neutrons were estimated to be in the range of 0.1001–0.1036 cm⁻¹. Radiation-shielding parameters, such as HVL, TVL, MFP, Z_eff, Z_eq, EBF and EABF values were found to be lesser and Σ_R values were greater than reported values for several boro-vanadate glasses, commercial glasses, IL, HSC, BM, ordinary concrete and ilmenite concretes. Radiation-protection efficiency of the present glasses was found to increase with La₂O₃ content and decrease with photon energy. Therefore, these glasses are proposed for both gamma- and neutron-shielding applications.

In this study, the impact of Si⁴⁺ substitution on the structural and dielectric properties of Ga₂O₃ powder was investigated in detail. High-temperature solid-state chemical reaction method was employed to prepare pure and Si-mixed Ga₂O₃ compounds. The formation of the monoclinic structure of Ga₂O₃ was confirmed through X-ray diffraction pattern. Field emission scanning electron microscopy micrographs revealed agglomerated particles. All prepared samples consisted of particles with sizes in the range of 0.191 to 0.202 µm. The X-ray photoelectron spectroscopy (XPS) analysis of Ga 2p reveals a positive shift as compared to metallic Ga due to the interaction between the electron cloud of adjacent ions. XPS analyses, which considered the Ga 2p doublet (Ga 2p_3/2 and Ga 2p_1/2 peaks), also indicate that Ga exists in its highest chemical valence state (Ga³⁺) in the sample. The frequency dependence of the dielectric constant, ac conductivity and dielectric loss of the synthesized samples was investigated at room temperature (RT). The dielectric constant increases with an increase in Si concentration at RT.

First principle calculations of the elastic constants of perovskite-type hydride NaBeH₃ material have been accomplished using the density functional theory (DFT) within the local density approximation (LDA) and the pseudopotential plane-wave method. The elastic constants were compared fairly well with those previously calculated. We have also calculated the dependence of the elastic constants on hydrostatic pressure from 0 up to 96.55 GPa. We have found that the elastic constants follow a quadratic law with respect to the pressure. In this study, the bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, acoustic wave speed and Debye temperature of cubic NaBeH₃ material are also determined as a function of pressure. Both the acoustic wave speed and the Debye temperature of NaBeH₃ material change monotonously and non-linearly with increasing the pressure from 0 up to 96.55 GPa.

Graphical Abstract

We synthesized La₂NiO₄ nanostructures using the cationic surfactant-based reverse micellar route and reported on the effect of the size and shape of the La₂NiO₄ nanostructures on their magnetic and photoelectrochemical properties. We satisfactorily refined the powder X-ray diffraction data in the tetragonal space group, I4/mmm. Magnetic susceptibility measurements were performed on all samples within the range of 5–300 K. The Curie–Weiss law determines the magnetic susceptibility of bulk La₂NiO₄, and a negative value for the Weiss temperature indicates antiferromagnetic exchange. The field-dependent magnetization curves of bulk La₂NiO₄ suggest a canted antiferromagnetic behaviour. The Mott–Schottky plot demonstrates that La₂NiO₄ is a p-type semiconducting material with holes as the primary charge carriers. Chronoamperometric measurements for these nanomaterials demonstrate excellent photostability of photocurrent.

Challenge of achieving high energy density (E) comparable with Li-ion batteries in supercapacitors, with low potential window offering aqueous electrolytes (1.2 V) has been overcome by using the electrode material composed of rGO 3.70%:PANI 51.86%:V₂O₅ 33.33%:SnO₂ 11.11% (GPVS). The GPVS exhibited different extents of energy storage in the presence of 1 M sulphuric acid (H₂SO₄) and acidified supernatant liquid (ASL), a green electrolyte. Here, the ASL is the by-product, which is obtained as supernatant liquid after the synthesis of GPVS composites in an in situ synthetic method, and acidified using conc. H₂SO₄. The energy storage obtained in the presence of ASL is 38% higher than the energy storage obtained in the presence of H₂SO₄. The GPVS exhibited a remarkable feature of amelioration of energy storage with increase in CV cycles in the presence of H₂SO₄. The GPVS exhibited an extraordinary cyclic stability up to 41,300 cycles. The energy storage parameters achieved in the presence of H₂SO₄ after 33,800 cycles are, a specific capacitance (C_s) of 694.44 F g^‒1, an E of 138.88 W h kg^‒1 (comparable with E of Li-ion batteries) and a power density (P) of 2.1020 kW kg^‒1 at 1 A g^‒1. The energy storage parameters achieved in the presence of ASL are, a C_s of 212.31 F g^‒1, an E of 42.46 W h kg^‒1 (comparable with E of Ni–Cd batteries) and a P of 3.1583 kW kg^‒1 at 2 A g^‒1. It is satisfying that all these high energy characters are achieved with the real two electrodes–supercapacitor cell step up. The green supercapacitors are made by using the by-product, which is obtained as supernatant liquid after the synthesis of GPVS as its electrolytes.

Improvement in mechanical properties of fibre-reinforced polymer composites through proper matrix modification has emerged as the significant trend in recent advanced technology. Dispersion of nanofillers in the matrix results in ultra-light weight, high strength, impact resistant and durable structures. In the current investigation, effect of the addition of varying percentages (0, 1, 3, 5 and 7 wt.%) of low-cost nanoclay to the unsymmetrical carbon/glass (C₂G₈) hybrid composites on mechanical, tribological and low-velocity impact (LVI) behaviour were investigated. Using traditional hand lay-up techniques, nanocomposite specimens were prepared. The results revealed that C₂G₈ hybrid composite with 5 wt.% loading of nanoclay possessed maximum hardness (35 HV), flexural strength (494 MPa), impact strength (Izod (119.022 kJ m⁻²), Charpy (563.922 kJ m⁻²)) and minimum specific wear rate (19.6 × 10⁻³ mm³ Nm⁻¹) in comparison with other hybrid combinations. LVI test also revealed enhanced energy absorption (112.46 J) for hybrid nanocomposite against plain C₂G₈ hybrid composite. Furthermore, the damage depth and areas were observed by visual inspection and scanning electron microscope to account for best possible structure–property relationship. Developed hybrid nanocomposite may be considered as a suitable material for various automotive applications.

In this investigation, we employ density functional theory with the generalized gradient approximation of Wu–Cohen and the modified Beck–Johnson approach. Our focus is on examining the structural, electronic and thermodynamic properties of ternary chalcopyrite CdXP₂ (X: Si and Sn) compounds. Our computed results of ternary structures for structural properties, for instance, tetragonal distortion, equilibrium lattice constants and bond lengths, show good agreement with the available results of the experimental and theoretical calculations. Our calculated positive results of cohesive energy and negative values of the formation energies of the title materials show their thermodynamic stability as well as highlight their possible experimental fabrication at these concentrations. From band structure calculations, it is found that the energy bandgap is of direct nature at Γ–Γ symmetry points for both ternary and quaternary alloys; however, the width of the bandgap is found to be decreased with increasing Sn concentration in the CdSi_1–xSn_xP₂ alloys. Moreover, thermodynamic properties using the quasi-harmonic Debye model are also computed. Our study provides a platform for further experimental and theoretical investigations to expose the potential of these materials for their applications.

Nanofilm CdS@Cd/Si heterojunctions have been fabricated by a two-step method. The obvious rectification effect can be observed. However, the leakage current density is relatively large. According to the criterion for judging the conduction model, three conduction mechanisms can be observed, which are the thermally generated electrons model, the Ohmic model and the space-charge-limited-current model from low voltage to high voltage, respectively. The preparation process of nanofilm CdS@Cd/Si heterojunctions by this two-step method, which directly grows nanofilm CdS@Cd on the silicon substrate to construct heterojunctions, can reduce the introduction of excessive defects and facilitate the release of stress in the interface.