Showing papers on "Lattice constant published in 2022"

Lanthanum substitution effect on the structural, optical, and dielectrical properties of nanocrystalline BaFe2O4 ferrites

Abstract: The effects of varying the amount of lanthanum infusion on the barium ferrite characteristics were investigated in this study. An orthorhombic structure formed as a majority phase and traces of barium lanthanum iron oxide as segregated phases in the ferrites composites. The optical bandgap energy values of the BaLaxFe2−xO4 nanoferrites were 3.50–3.72 eV. SEM confirmed that the prepared nanoferrites had spherical morphology with size of 66.50–81.50 nm. The dielectric parameters of BaLaxFe2−xO4 nanoferrites were studied in the specified spectrum, which revealed the La doped barium nanoferrites had a low dielectric constant and conductivity properties compared to the barium nanoferrites. The saturation magnetization (60.03–25.98 emu g−1) and coercivity (454.85–80.65 Oe) of the prepared nanoferrites were improved due to an effect of La3+ ions. Accordingly, the observed optical bandgap energy, dielectric constant, and magnetism could be employed in high-frequency magneto-optoelectronic systems.

Numerical and experimental investigations of Novel nature inspired open lattice Cellular structures for enhanced stiffness and specific energy absorption

Abstract: Lattice structures are meant for light weight structure with a high strength to weight ratio used to carry high loads and high energy absorption capabilities. In the lattice structures, the non-stochastic arrangement of members has the ability to control and customize their mechanical properties. The recent developments in additive manufacturing provides freedom in design and gives flexibility to manufacture tailored complex novel lattice structures. In the present investigation, the traditional 2.5D honeycomb and the tessellated open lattice structures with basic crystalline arrangements of the members are considered to study the load carrying capacity, stiffness and energy absorption capabilities by keeping constant volume for each lattice. The results through the experiments and finite element analysis are compared with a novel open lattices structure to show significant improvement in stiffness and high energy absorption with the volume of the material. However, the novel open lattice structure has displayed prominent post yield plateau stresses and energy absorption with sacrificing stiffness and strength significantly.

Synthesis and structural studies of superconducting perovskite GdBa2Ca3Cu4O10.5+δ nanosystems

Abstract: GdBa 2 Ca 3 Cu 4 O 10.5+δ superconducting perovskite nanomaterial is prepared by subsequent steps viz. weighing, mechanical mixing, ball milling, attrition milling and calcination, and applying solid state reaction technique. By XRD studies of GdBa 2 Ca 3 Cu 4 O 10.5+δ /GBCCO nanosystems (prepared at various calcination temperatures—30, 500, 850, and 900°C) crystallinity of the samples are confirmed. Using XRD results and applying XPERT PRO software, the lattice parameters and orthorhombic crystal system of the ceramic sample are analyzed. Structural parameters such as d spacing, dislocation density and number of particles per unit surface area are determined as functions of calcination temperature for preferred high intensity peaks (110), (111), (321), and (521). Particle size of preferred orientations at various calcination temperatures are obtained by XRD diffraction peak profile analysis methods such as Debye Scherrer's formula, Cauchy equation, and Williamson Hall (WH) plot method and nanostructure property is confirmed. WH plot also yields the values of lattice strain. It is observed that calcination temperature affects structural parameters.

Synthesis and Characterization of High Entropy Alloy 23Fe-21Cr-18Ni-20Ti-18Mn for Electrochemical Sensor Applications

Abstract: High entropy alloys (HEA) are one of the modern-era alloys accelerating with greater velocity because of their excellent properties and different applications. In the present paper, we have successfully fabricated HEA (23Fe-21Cr-18Ni-20Ti-18Mn) powders by ball milling the elemental Fe, Cr, Ni, Ti, and Mn powders for 15 h. The advancement of the milling process and phase transformation of HEAs were studied by using X-ray diffraction (XRD) and scanning electron microscope (SEM). The crystallite size and the lattice strain of the HEA were calculated by using the Williamson-Hall (W-H) equation and the values were found to be 7 nm and 0.0176%, respectively. Similarly, the true lattice parameter was calculated using the Nelson–Riley (N-R) extrapolation method, and the value was found to be 3.544 Å. We have successfully investigated the electrochemical response of 15 h ball milled 23Fe-21Cr-18Ni-20Ti-18Mn HEA powders to determine the ascorbic acid (AA) using cyclic voltammetry. We have modified the carbon paste electrode with ball milled HEA of concentrations 0, 2, 4, 6, 8, and 10 mg, and among them, 8 mg HEA modified carbon paste electrode (HEA-MCPE) depicted the highest current sensitivity. We reported the effect of modifier concentration, analyte concentration, scan rate, and pH on the oxidation peak of AA. The electrochemical active surface area of carbon paste and MCPE was calculated using the Nernst equation and the values were found to be 0.0014 cm2 and 0.0027 cm2, respectively. The fabricated HEA-MCPE showed excellent current sensitivity, stability, anti-fouling, and selectivity.

Quasi-Freestanding Bilayer Borophene on Ag(111).

Abstract: The lattice structure of monolayer borophene depends sensitively on the substrate yet is metallic independent of the environment. Here, we show that bilayer borophene on Ag(111) shares the same ground state as its freestanding counterpart that becomes semiconducting with an indirect bandgap of 1.13 eV, as evidenced by an extensive structural search based on first-principles calculations. The bilayer structure is composed of two covalently bonded v1/12 boron monolayers that are stacked in an AB mode. The interlayer bonds not only localize electronic states that are otherwise metallic in monolayer borophene but also in part decouple the whole bilayer from the substrate, resulting in a quasi-freestanding system. More relevant is that the predicted bilayer model of a global minimum agrees well with recently synthesized bilayer borophene on Ag(111) in terms of lattice constant, topography, and moiré pattern.

Design and mechanical testing of porous lattice structure with independent adjustment of pore size and porosity for bone implant

Abstract: Porosity is considered to be one of the key factors affecting the structural properties of porous lattices, but in fact, pore size also plays an important role, and it has great potential to adjust pore size and porosity independently to improve structural properties. In this work, by adjusting the sheet thickness of the triply periodic minimal surface (TPMS) lattice structures and adjusting the height of the single row structure according to linear and constant laws, the TPMS lattice structures with given porosity and adjustable pore size are designed, and the mechanical response is investigated. Based on preparing samples by Ti6Al4V laser powder bed fusion, the results of the tests show that the elastic modulus ranges of linear change TPMS (LC-TPMS) and constant TPMS (C-TPMS) lattice structures are 3625.6 MPa–4575.1 MPa and 3820.0 MPa–4509.1 MPa, respectively. In the plateau stage, the LC-TPMS lattice structures have a longer and more stable plateau stage, higher yield stress and better energy absorption capacity than the C-TPMS lattice structures. The maximum energy absorption difference is 62.7 MJ/mm 3 and the maximum energy absorption efficiency difference is 0.12. The LC-TPMS lattice structures can also obtain a larger damping ratio under larger compressive strain.

Study of Optical and Thermoelectric Properties of Double Perovskites Cs2KTlX6 (X = Cl, Br, I) for Solar Cell and Energy Harvesting

Abstract: The double perovskites have emerging optical properties and extensively studied solar cells and renewable energy. In this work, we have investigated the optical, electronic and transport properties of Cs 2 KTlX 6 (X = Cl, Br, I) using density functional theory. The thermodynamic stability is determined from the calculation of enthalpy of formation and structural stability is probed by computing the tolerance factor. Energy-volume optimization graphs reveal that lattice constant increased (11.31–12.80 Å) and bulk modulus decreased (20.46–15.90 GPa) with the increasing size of halogens. The optical properties are computed using TB-mBJ which reveals direct bandgaps (3.10, 2.0, 0.96) eV for (Cl, Br, I). In addition, the dielectric constant, refractive index, and reflectivity has been discussed in detail in the energy range of 0–6 eV. The absorption bands are recorded in infrared, visible and ultraviolet regions for Cl, Br and I based DPs. The temperature and chemical potential dependent transport properties are computed using BoltzTrap code. The appropriate values of thermoelectric parameters with high figure of merit at room temperature show the potential of these DPs for thermoelectric applications. (a) Absorption of light energy (b) Figure of merit.

Structural characteristics, cation distribution, and elastic properties of Cr3+ substituted stoichiometric and non-stoichiometric cobalt ferrites

Abstract: Structural, elastic and cation distribution properties have been investigated on stoichiometric and non-stoichiometric cobalt ferrites. Crystal structure, formation of spinel type ferrite, chemical bonding, cation distribution, and thermal properties of two series of Cr3+ substituted stoichiometric and non-stoichiometric various cobalt ferrites with general formula Co1−xCrxFe2O4 (S1), and Co1+xCrxFe2−xO4 (S2) were reported. Samples are synthesized by the solid-state reaction technique via planetary ball milling. X-ray diffraction (XRD) analysis confirms the formation of a single phase cubic spinel structure with the space group Fd3̄m. Rietveld refinement results show that Cr occupies both the tetrahedral (A-site) and octahedral sites (B-site). The experimental lattice parameters show increasing trends for both the series with increase of Cr content. The cation–anion vacancies, chemical bonding, and the displacement of oxygen have been evaluated to understand the effect of Cr substitution and how the non-stoichiometry affects the physical and chemical properties of the material. The crystallite size is found to be the decreasing value with an increase of Cr concentration for both series of samples. Specific vibrational modes from the FTIR spectra suggest a gradual change of inversion of the ferrite lattice with the increase of Cr concentration which is also evident from Rietveld refinement data. The elastic properties analysis reveals that the synthesized samples for both series are ductile in nature. The non-stoichiometric structure with excess Co2+ may pave a new way to realize the lowering of Curie temperature of ferrite that is expected to improve the magnetocaloric properties.

Dependence of Structural, Morphological and Magnetic Properties of Manganese Ferrite on Ni-Mn Substitution

Abstract: This paper presents the influence of Mn2+ substitution by Ni2+ on the structural, morphological and magnetic properties of Mn1−xNixFe2O4@SiO2 (x = 0, 0.25, 0.50, 0.75, 1.00) nanocomposites (NCs) obtained by a modified sol-gel method. The Fourier transform infrared spectra confirm the formation of a SiO2 matrix and ferrite, while the X-ray diffraction patterns show the presence of poorly crystalline ferrite at low annealing temperatures and highly crystalline mixed cubic spinel ferrite accompanied by secondary phases at high annealing temperatures. The lattice parameters gradually decrease, while the crystallite size, volume, and X-ray density of Mn1−xNixFe2O4@SiO2 NCs increase with increasing Ni content and follow Vegard’s law. The saturation magnetization, remanent magnetization, squareness, magnetic moment per formula unit, and anisotropy constant increase, while the coercivity decreases with increasing Ni content. These parameters are larger for the samples with the same chemical formula, annealed at higher temperatures. The NCs with high Ni content show superparamagnetic-like behavior, while the NCs with high Mn content display paramagnetic behavior.