Search

In this study, we have investigated the structural, electrical transport and UV–Visible properties of polycrystalline La0.7Ca0.3−xKxMnO3 (x = 0.0, 0.05, 0.10, 0.20) ceramic samples prepared by conventional solid-state reaction. The structure characterized by X-ray diffraction shows that the samples possess orthorhombic perovskite structure belonging to Pnma space group with some impurity for higher doping level (x = 0.10, 0.20) and cell volume is enlarged with Ca2+ substitution by K1+. The surface morphology was investigated by field emission scanning electron microscope, which indicates that the samples with better crystallization having higher density. The electrical transport properties were measured by the standard four-probe method, which demonstrates that the resistivity decreases non-monotonically and the metal–insulator transition temperature (TP) shifts to higher temperature with increasing K1+ content, the electrical transport behavior for metal and insulator region was explained using Zener double exchange model and small polaron hopping model respectively. Furthermore, the progressive substitution of Ca2+ by K1+ broadens the metal–insulator transition and reduces the temperature coefficient of resistivity. Room temperature UV–Vis studies show that the optical band gap changes with the partial replacement of Ca2+ with K1+. The investigations clearly show the effect of impurity present on structural, electrical transport and UV–visible response of the prepared ceramic samples.

Ferroelectric HfO2-based materials hold great potential for widespread integration of ferroelectricity into modern electronics due to their robust ferroelectric properties at the nanoscale and compatibility with the existing Si technology. Earlier work indicated that the nanometer crystal grain size was crucial for stabilization of the ferroelectric phase of hafnia. This constraint caused high density of unavoidable structural defects of the HfO2-based ferroelectrics, obscuring the intrinsic ferroelectricity inherited from the crystal space group of bulk HfO2. Here, we demonstrate the intrinsic ferroelectricity in Y-doped HfO2 films of high crystallinity. Contrary to the common expectation, we show that in the 5% Y-doped HfO2 epitaxial thin films, high crystallinity enhances the spontaneous polarization up to a record-high 50 µC/cm2 value at room temperature. The high spontaneous polarization persists at reduced temperature, with polarization values consistent with our theoretical predictions, indicating the dominant contribution from the intrinsic ferroelectricity. The crystal structure of these films reveals the Pca21 orthorhombic phase with a small rhombohedral distortion, underlining the role of the anisotropic stress and strain. These results open a pathway to controlling the intrinsic ferroelectricity in the HfO2-based materials and optimizing their performance in applications.

Compared with antiferroelectric (AFE) orthorhombic R phases, AFE orthorhombic P phases in NaNbO3 (NN) ceramics have been rarely investigated, particularly in the field of energy-storage capacitors. The main bottleneck is closely related to the contradiction between difficultly-achieved stable relaxor AFE P phase and easily induced P-R phase transition during modifying chemical compositions. Herein, we report a novel lead-free AFE ceramic of (1-x)NN-x(Bi0.5K0.5)ZrO3 ((1-x)NN-xBKZ) with a pure AFE P phase structure, which exhibits excellent energy-storage characteristics, such as an ultrahigh recoverable energy density (Wrec) ∼4.4 J/cm3 at x = 0.11, a large powder density PD ∼104 MW/cm3 and a fast discharge rate t0.9 ∼45 ns. The analysis of polarization-field response, Raman spectrum and transmission electron microscopy demonstrates that the giant amplification of Wrec by ≥177% should be mainly ascribed to the simultaneously and effectively enhanced AFE P-phase stability and its relaxor characteristics, resulting in a diffused reversible electric field-induced AFE P-ferroelectric phase transition with concurrently increased driving electric fields. Different from most (1-x)NN-xABO3 systems, it was found that the reduced polarizability of B-site cations dominates the enhanced AFE P-phase stability in (1-x)NN-xBKZ ceramics, but the almost unchanged tolerance factor tends to cause the AFE R phase to be induced at a relatively high x value.

NaNbO3-based ceramics usually show ferroelectric-like P-E loops at room temperature due to the irreversible transformation of the antiferroelectric orthorhombic phase to ferroelectric orthorhombic phase, which is not conducive to energy storage applications. Our previous work found that incorporating CaHfO3 into NaNbO3 can stabilize its antiferroelectric phase by reducing the tolerance factor (t), as indicated by the appearance of characteristic double P-E loops. Furthermore, a small amount of MnO2 addition effectively regulate the phase structure and tolerance factor of 0.94NaNbO3-0.06CaHfO3 (0.94NN-0.06CH), which can further improve the stability of antiferroelectricity. The XRD and XPS results reveal that the Mn ions preferentially replace A-sites and then B-sites as increasing MnO2. The antiferroelectric orthorhombic phase first increases and then decreases, while the t shows the reversed trend, thus an enhanced antiferroelectricity and the energy storage density Wrec of 1.69 J/cm3 at 240 kV/cm are obtained for 0.94NN-0.06CH-0.5%MnO2(in mass fraction). With the increase of Mn content to 1.0% from 0.5%, the efficiency increases to 81% from 45%, although the energy storage density decreases to 1.31 J/cm3 due to both increased tolerance factor and non-polar phase.

The light rare earth Pr/Ce-contained (Tb0.2Pr0.8)1–xCexFe1.93 (0 ≤ x ≤ 1.0) intermetallics were arc melted and magnetoelastic properties were investigated. The compounds of x ≥ 0.40 are found to stabilize at ambient pressure in a single Laves phase with MgCu2-type C15 structure, which is attributed to the strong Ce 4f bonding. The mixed-valence behavior, with a support of the deviation from the linear Vegard’s law for both lattice parameter a and saturation magnetization MS, is observed at room temperature. The easy magnetization direction (EMD) was determined by the analysis of XRD on both magnetically aligned samples and the (440) splitting, that is, EMD lies toward axis for x ≤ 0.50 rotating to for x = 0.60, accompanied with the structural distortion from rhombohedral to orthorhombic. The substitution of Ce for Tb/Pr is conductive to the reduction of magnetocrystalline anisotropy, giving rise to an improvement of the low-field magnetostriction. The excellent magnetoelastic properties can be tailored by the Ce introduction, e.g., the spontaneous magnetostriction coefficient λ111 as large as 1150 × 10−6 for x = 0.40, and the low-field induced magnetostriction achieving a high value of λa = 180 × 10−6 at 80 kA/m for x = 0.60. The excellent magnetoelastic properties and the combination in high Pr-content with low cost, suggest promising prospects in applications.

Structural, optical and magnetic properties are reported for new synthesized perovskite materials. Ba0.3La0.7Ti0.3Fe0.7O3 and Ba0.1La0.9Ti0.1Fe0.9O3 compositions were prepared via solid state reaction. X-ray analysis confirms that both compositions show feature of perovskite structure. Rietveld refinement method was used to confirm the phase formation and investigate the structure and space group. The study demonstrates the formation of orthorhombic structure with Pnma space group for Ba0.3La0.7Ti0.3Fe0.7O3 while the composition Ba0.1La0.9Ti0.1Fe0.9O3 structure adopts Pbnm symmetry. UV-vis spectroscopy measurements show very broad and intense UV-visible light absorption, the estimated band gap ranges between 2.07 and 2.15 eV. Magnetic measurements were carried out for the compositions Ba0.3La0.7Ti0.3Fe0.7O3 and Ba0.1La0.9Ti0.1Fe0.9O3. The hysteresis loop of both samples at 300 and 10 K show a strong ferromagnetic behavior. The temperature dependent magnetization at 0.05 T under field-cooled (FC) and zero field cooled (ZFC) modes shows magnetic frustration or spin glass-like behavior.

LnMnO3+σ (Ln = La, Pr, Nd, Sm, Eu, Gd or Dy) perovskites synthesized by sol-gel method were employed for gaseous elemental mercury (Hg0) removal from coal-fired flue gas. Characterization results revealed the structure of the perovskites presented a phase transition process from rhombohedral system to O- and O'-orthorhombic structure with the change of A-site rare earth elements. The perovskites showed satisfactory Hg0 removal capacity in a narrow temperature range of 100–150°C. NdMnO3+σ with an O-O’ orthorhombic structure presented the best Hg0 removal performance, which markedly depends on four factors: crystal structure, oxygen vacancy density, Mn4+/Mn3+ ratio and surface element segregation. The Hg0 removal mechanism was illustrated based on the mercury temperature programmed desorption experiment and X-ray photoelectron spectroscopy characterization. Both chemisorption and catalytic oxidation played a role in the Hg0 removal process. Chemisorption dominated the Hg0 removal, due to the slow catalytic oxidation rate at low temperature. This work preliminarily established the relation between the structure of rare earth manganese perovskite and Hg0 removal performance.

Perovskite functional ceramics have been widely applied for thermal protection owing to their unique physical properties. However, formation of oxygen vacancies under external stimuli usually limits their performance in practical applications. Therefore, the mechanism of the effect of oxygen vacancy on the layer structure of perovskite La0.9Sr0.1TiO3+δ was investigated by experiments and first-principles simulations. The experimental results showed that the lattice distortion occurred in oxygen-deficient environment to give a longer c-axis, along with a significant adjustment in the modes of A/B–O bond vibration, resulting in lower reflectivity. Advanced transmission electron microscopy studies revealed that oxygen vacancies induced localized atomic rearrangements via [TiO6] layer movements to adapt to the lattice distortion. This eventually restructured a part of the layer interfaces by expanding the overlapping projection of atoms in the c-axial direction. The specific transformation process was described as a compendious process, while geometric phase analysis effectively clarified how oxygen vacancies can inhibit reflectivity on the layer structure. Thus, this study provides effective approaches for researching the effects of oxygen vacancy on the physical properties of orthorhombic layer perovskite structures, which may facilitate the development of perovskite-based functional devices.

In this paper, the crystallization behavior of a novel poly(monothiocarbonate), poly(trimethylene monothiocarbonate) (PTMMTC), was investigated and compared with its polycarbonate analogue, poly(trimethylene carbonate) (PTMC). It is found that PTMMTC exhibits strong crystallizability, while unstretched PTMC is amorphous. DSC and DMA results reveal that PTMMTC possesses higher glass transition temperature (Tg) and β-transition temperature (Tβ) than PTMC. Simulation based on density functional theory (DFT) shows that, the bond angle of C-S-C is evidently smaller than that of C-O-C, and thus a larger dipole moment. This leads to the stronger intermolecular interaction and more rigid chain conformation in PTMMTC, which is the origin of sulfur-substitution enhanced crystallization. The crystal structure of PTMMTC was preliminarily determined for the first time. PTMMTC has an orthorhombic crystal structure with a planar zig-zag chain conformation. The parameters of unit cell are a = 10.74 A, b = 4.79 A, and c (fiber axis) = 7.74 A.

A glass ceramic from the MgO–Al2O3–SiO2 system containing additives of ZrO2, TiO2, La2O3 and P2O5 was investigated. Via x-ray powder diffraction (XRPD) and Transmission electron microscopy(TEM) the crystalline phases present could be identified as MgAl2O4 (Spinel), orthorhombic ZrTiO4 and a polymorph of LaPO4 with a previously unknown crystal structure. The crystal structure of this LaPO4 phase was solved ab initio via 3D ED Data. The polymorph occurs in a distorted barite structure type in the same space group (P21/n) as the stable monazite type polymorph, however the density is higher and the La has a higher coordination number. Furthermore the LaPO4 is present in a spinodal relict microstructure. Potential explanations for the presence of this metastable polymorph are pressure due to residual stresses from the crystallization or surface effects due to the high surface area resulting from the spinodal relict structure.

Ca-doped Ni–Mg–Mn spinel ferrites with compositions of Ni0·5Mg0·3Mn0.2CaxFe2-xO4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared via sol-gel auto-ignition technique. TGA/DTA, FTIR, XRD, FESEM, and VSM were employed to evaluate the thermal, spectral, structural, morphological, and magnetic features of Ca-doped Ni–Mg–Mn spinel ferrites. TGA/DTA curves show the weight loss in the sample. This weight loss was attributed to the oxidation and decomposition of the sample contents at a temperature of 500 °C. XRD reveals a single-phase structure of the Ni–Mg–Mn nano ferrites. A single-phase orthorhombic structure was confirmed for Ca-doped Ni–Mg–Mn ferrites. Structural parameters such as lattice parameter, ‘da’, ‘db’, ‘dc’, and ‘dv’ were evaluated using unit cell software. The absorption peaks at 427 to 538 cm−1 confirmed the spinel structure, which was evaluated using FTIR. FESEM analyses showed that the agglomerations increased with the doping of Ca in Ni–Mg–Mn ferrites. Remanence, Y–K angles, saturation, coercive force, magnetic squareness, magnetic moment, and anisotropy constant were determined for Ca-doped Ni–Mg–Mn spinel ferrite samples. It is noticed that saturation increases from 29.157 to 51.322 emu/g, whereas remanence increased from 5.34 to 9.40 emu/g, respectively. The permeability, anisotropy constant, and magnetic moments were also found to increase with Ca doping. However, the Y–K angles increased with Ca concentration in Ni–Mg–Mn nano ferrites. In addition, the switching field distribution (SFD) and high-frequency response of all the Ca-doped Ni–Mg–Mn samples were also evaluated. Ca-doped Ni–Mg–Mn samples are suggested to be suitable for switching, filters, inductors, and microwave absorption applications because of the superparamagnetic nature of the prepared spinel ferrites.

Nanostructured HoFeO3 powders were obtained by solution combustion method at various glycine-nitrate ratios (G/N = 0.2, 0.4, …, 1.4). According to X-ray powder diffractometry data, the presence of two modifications of HoFeO3 in the synthesized samples was established: orthorhombic (Pbnm) and hexagonal (P63/mmc). The crystallite size of the obtained compositions varies from 62 ± 6 to 29 ± 3 nm, depending on the G/N ratio. From magnetic structure studies, it is found that HoFeO3 obtained with a stoichiometric amount of glycine in the reaction solution is in the magnetically ordered state and is represented by a sextet with quadrupole splitting (QS) = 0 mm/s, isomeric shift (IS) = 0.36 mm/s and effective field strength (Heff) = 497 kOe. According to the results of vibrational magnetometry, it is found that the orthoferrites obtained have a ferromagnetic structure, the main parameters of which (Ms, Mr and Hc) systematically change with a change in the redox ratio of the reaction mixture and, as a consequence, their phase composition, and reach maximum values at a G/N ratio = 0.6. In the samples obtained with a significant excess and lack of glycine (G/N = 0.2 and 1.4), despite their amorphous nature, hysteresis loops characteristic of the ferromagnetic state of the substance is observed. It is hopeful to obtain a pure hexagonal modification of HoFeO3 via heat treatment on amorphous products of glycine-nitrate combustion.

Nanosized Ba1-xBixFe1-xCuxO3 (12–50 nm) with x values of 0, 0.01, 0.05, and 0.1 system was prepared using the Pechini method. Structural, morphological, surface and optical characterizations were performed for the prepared samples. Cubic phase was the predominant phase for the undoped BaFeO3 and Bi and Cu co-doped BaFeO3 samples. Minor phases of monoclinic Ba2Fe2O5, orthorhombic BaFe2O4 and orthorhombic BaCO3 were identified for all the prepared samples. Ba0.95Bi0.05Fe0.95Cu0.05O3 sample has the lowest band gap (2.43 eV). 98.1% paracetamol removal was achieved with 0.75 g/L of Ba0.95Bi0.05Fe0.95Cu0.05O3 at pH 9 after 120 min. The paracetamol degradation follows the pseudo first-order kinetics. HO• is the main oxidative species responsible for the paracetamol degradation. Gas chromatography–mass spectrometry (GC–MS) analysis was performed at the end of the photocatalytic degradation experiment under optimum operating condition using Ba0.95Bi0.05Fe0.95Cu0.05O3 to explain the reaction mechanism and identify the intermediate by-products which is confirmed by ultraviolet/visible (UV/Vis) spectroscopy study at different reaction times.

Cerium (Ce3+) doped strontium, barium orthogermanate samples are prepared by conventional solid state mixing method. In this process, X-ray powder diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDAX) and Photoluminescence (PL) measurements are carried out for the synthesized phosphors. The orthorhombic structure is confirmed by X-ray diffraction of the phosphors. EDAX is confirmed that all the elements are present in the compound such as Sr, Ba, Ge, O and Ce. Photoluminescence studies of Sr2GeO4: Ce3+ and Ba2GeO4: Ce3+ phosphors show intense blue emissions at 438 and 429 nm under ultraviolet excitation respectively. These phosphors are ascribed due to the 5d → 2F5/2, 2F7/2 electronic transitions of cerium ions. Therefore, these phosphors may be applicable in the display devices and lamp industry as blue emitting phosphors.

Formation of β′ phase in long-period stacking ordered (LPSO) structures in an Mg88Co5Y7 (at.%) alloy after aging at 200 °C for 24 h or electron beam (EB) irradiation has been studied by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). β′ phase was precipitated only in the Mg matrix but not in LPSO structures after aging at 200 °C for 24 h. LPSO structure containing stacking defects transforms into the β′-long phase during EB irradiation, which plays a key role in accelerating solute atoms’ diffusion. New complex β′(LPSO) structures formed in the alloy after EB irradiation, such as β′(12H) structure with an orthorhombic lattice (Mg7Y, Cmcm, a = 2a0 = 0.642 nm, b = 4 3 a0 = 2.27 nm, c = 6c0 = 3.12 nm).

Li/Ce co-doped BaBi4Ti4O15–Bi4Ti3O12 (BBT-BIT) intergrowth bismuth layer-structured piezoelectric ceramics were prepared by conventional solid-state method. The X-ray diffraction, Raman spectroscopy, and scanning electron microscopy results showed that all the samples had a single orthorhombic phase structure, indicating that Li/Ce dopants had successfully dissolved into the BBT-BIT lattice. Li/Ce co-doping improved the piezoelectric properties of the ceramics: d33 increased from 6.8 pC/N to 21.4 pC/N and the Curie temperature Tc increased from 483 °C to 544 °C. Among all the ceramics investigated, the Ba0.7(Li0.5Ce0.5)0.3Bi8Ti7O27 ceramic showed the best comprehensive properties with d33 = 20.2 pC/N, Tc = 540 °C, tanδ = 0.53%, Ea = 1.13 eV, 2Pr = 10.5 μC/cm2. Meanwhile, the hysteresis loop of the BBT-BIT-0.3(Li0.5Ce0.5) sample sintered in an oxygen atmosphere was asymmetric, which may have been caused by defects produced by the Li/Ce co-doped. Besides, a d33 value of 18.5 pC/N was achieved at 450 °C, which is 91.6% of the value at room temperature, indicating the good thermal stability of the ceramic. The sample showed high resistivity, which can be attributed to the decrease in the concentration of the oxygen vacancies. Our results suggest the great potential of Li/Ce co-doped BBT-BIT intergrowth piezoelectric ceramics for high-temperature applications.

Single crystal of Sulphamic acid Lithium chloride (SALC), the inorganic nonlinear optical material was synthesized by slow solvent evaporation technique. PXRD analysis confirmed the grown crystal belong to orthorhombic structure to space group of Pbca. The vibrationally assigned frequencies of FTIR were obtained experimentally and compared with theoretical assigned values were calculated by DFT/B3LYP with 6–311++G(d,p) basis set by Gaussian 09 W software. The Vickers micro hardness study led to the evaluation of crystal belongs to hard category. The calculated FMO energy values indicate the charge transfer occurs within the molecule. The hyperpolarizability values of the grown molecule have been computed.

Commonly-used seismic fracture characterization method assumes one single fracture set, and this article aims to relax the limitation and demonstrate the feasibility of seismic characterization for two sets of orthorhombic fractures. Elastic properties of orthorhombic fractures can be studied using a model of horizontal and vertical fractures as linear-slip interfaces embedded in an isotropic background. High fracture density in hydrocarbon reservoirs is the ``sweet spot'' of effective permeability for fluid flow, and seismic characterization of orthorhombic fractures using the variations in reflection amplitude versus offset and azimuth (AVOAz) helps to optimize the production of naturally fractured reservoirs. Based on an effective orthorhombic linear-slip model, we first construct the effective elastic stiffness matrix in terms of elastic moduli and decoupled horizontal and vertical fracture densities under the assumption of weak anisotropy (WA) or small fracture densities. Using the scattering function and first-order perturbation in effective elastic stiffness components, we derive a WA and linearized PP-wave reflection coefficient containing decoupled orthorhombic fracture densities to describe the characteristics of horizontal and vertical fracture sets. We then propose an efficient AVOAz inversion method to perform the seismic characterization of decoupled orthorhombic fracture densities based on observed surface azimuthal amplitude data in a Bayesian framework. We finally apply the inversion approach to synthetic and field datasets to demonstrate its feasibility and reasonability in orthorhombic fracture characterization.

Black phosphorus (BP) is a new layered material in concept, which has attracted great interest due to its fascinating optical and electrochemical properties. Here, we report the large scale synthesis of BP (20 g) by reducing PCl5 with metallic Al in melt AlCl3 at 300 °C. X-ray diffraction indicates the orthorhombic structure of BP and Raman spectrum shows that there is no obvious impurities. BP samples consist of micron-sized clusters of about 2 µm aggregated by flake-like nanoparticles with 20–100 nm. When used as anode materials for lithium ion battery, it exhibits a high specific capacity of 1610 m Ah g−1 at a current density of 0.1C, and cycle life up to 1000 cycles at a current density of 5C. In addition, through gradient centrifugation of as-prepared BP samples, gram-scale BP quantum dots can be obtained.

Ca1-xCexBi2Nb1.975(Cu0.25W0.75)0.025O9 (CBNCW-xCe: x = 0.00, 0.02, 0.04, 0.06, and 0.09) lead-free piezoelectric ceramics with improved piezoelectric properties were prepared by the traditional solid-state reaction method. The effects of CeO2 doping on the microstructure and electrical properties were investigated in detail. XRD patterns and Rietveld refinement show that the crystal structures of the samples transform from the orthorhombic phase into the pseudotetragonal phase and that the lattice distortion is weakened. Raman and XPS spectra indicate that Ce ions exist with +3 and + 4 valences in the air sintered ceramics, in which Ce4+ replaces Nb5+, causing the weakened NbO6 octahedral vibration of torsional and tensile and an increase in oxygen vacancies in the doped ceramics. When x = 0.04, it shows excellent comprehensive properties with a high d33 value of 18.1 pC/N, a Tc value of 900 °C, and a ρdc value of 2.8 × 105 Ω cm at 500 °C. Our results suggest that the CBNCW-0.04Ce ceramic is a promising candidate in high-temperature piezoelectric applications.

Many ABX3 perovskite compounds adopt at temperatures of interest a low-symmetry structure, rather than the ideal (cubic) structure. The prototypical case is the mineral perovskite (CaTiO3), which exhibits orthorhombic symmetry over a wide range of temperatures, attaining ideal, cubic symmetry only at very high temperatures. In this study, we made use of this behaviour to examine the effect of crystal symmetry on oxygen diffusion in a single perovskite material. Employing molecular dynamics (MD) simulations, we calculated oxygen tracer diffusion coefficients in CaTiO3, doped with various acceptor species, in the range 1000 ≤ T/K ≤ 2500. The activation enthalpy of oxygen tracer diffusion was found to be larger for the orthorhombic structure (0.58 eV) than for the cubic structure (0.43 eV). In addition, oxygen tracer diffusion was found to be adversely affected by the presence of acceptor-type cation defects, with stronger effects being observed for the low-symmetry structure. Our results also allow us to suggest explanations for the large scatter observed in experimental transport studies; to derive trends for the alkaline-earth perovskites; and to emphasise the merits of using MD simulations, rather than static calculations, to obtain activation barriers for ion migration in the high-symmetry forms of distorted perovskites.

BaO-Sm2O3–5TiO2 (BST) added by Al2O3 was prepared by solid-state reaction method. The main phase is Ba3.99Sm9.34Ti18O54 of orthorhombic tungsten bronze structure, and the secondary phase is Ba1.18Al1.90Ti6.09O16 of tetragonal structure, which has two types of grains: one is grey and cubic, and the other is white and quasi-rectangular. Microstructure was characterized by XRD, SEM, and Raman spectra. Micromechanical properties of different phases were assessed by nanoindentation and micro-scratch tests with Berkovich indenter. Volume fractions of different phases obtained by statistical analysis of grid indentation are in good agreement with those obtained by XRD analysis. Vickers hardness method is more appropriate for the determination of the fracture toughness of dielectric ceramics. BST ceramic without addition of Al2O3 has better mechanical properties than BST-A with addition of Al2O3, indicating that addition of Al2O3 impairs the micromechanical properties of dielectric ceramics.

Orthorhombic magnesium niobate is known to exhibit exceptional dielectric and photoluminescence properties. With the intention to evaluate these properties, MgNb2O6 (MN2) was synthesized at 900 °C for 6 h through a two-stage process. The phase examination was done by XRD and Raman spectroscopy. XRD analysis confirmed orthorhombic crystal structure with average crystallite size of 41 nm, approximately. The d-value and (hkl) plane corresponding to highest intensity was examined 2.9486 A and (3 1 1), respectively. Raman spectroscopic analysis clarified various vibration bands of MN2 ceramics. The grain size was assessed close to 87 nm from FESEM analysis considering the grain distribution plot. The microstructure analysis by HRTEM reveal nanoparticles of average size of 41.83 nm. The clear lattice image and prominent spots in SAED confirm crystallinity of prepared ceramics. The PL result of the prepared ceramics at 900 °C indicated blue emission spectrum near 442 nm. The material prepared at 900 °C exhibited band gap of 2.65 eV using diffuse reflectance spectroscopic analysis. The dielectric constant (er) and tanδ were also investigated where er was measured 27.8 and 20.8 for material prepared at 800 and 900 °C, respectively. Low tanδ (dielectric loss) was also noted in present investigation.

Ni doped V2O5 nanorods were synthesized by simple sol–gel route. The effect of Ni doping has been studied through XRD, Micro-Raman, SEM and CV analysis. The XRD result shows that the synthesized samples were exhibits orthorhombic structured V2O5. SEM images illustrate the Ni particles are decorated on the V2O5 rod surfaces. From the Raman analysis, the prepared samples are observed in V-O vibrational modes without impurities. Both V2O5 and Ni:V2O5 electrodes are exhibits pseudocapacitance nature, which shows the superior specific capacitance values for 112 and 152 Fg−1 at 10 mVs−1, respectively.

MgNb2-xVx/2O6-1.25x (0.1≤x≤0.6) ceramics with orthorhombic columbite structures were prepared at low-temperature by a solid-phase process. The phase component, microscopic morphology, low-temperature sintering mechanism and microwave dielectric performance of MgNb2-xVx/2O6-1.25x ceramics were comprehensively investigated. Low-temperature sintering densification of dielectric ceramics was achieved via the nonstoichiometric substitution of vanadium (V) at the Nb-site. In contrast to pure MgNb2O6 ceramics, the sintering temperature of MgNb2-xVx/2O6-1.25x (x = 0.2) ceramics was reduced by nearly 300 °C owing to the liquid-phase assisted sintering mechanism. The liquid phase arises from the autogenous low-melting-point phase. Meanwhile, MgNb2-xVx/2O6-1.25x (x = 0.2) samples with nonstoichiometric substitution could achieve a more than 900% improvement in the Q × f value, compared with stoichiometrically MgNb2-xVxO6 (x = 0.1, 0.2) ceramics. Finally, MgNb2-xVx/2O6-1.25x dielectric ceramics possess outstanding microwave dielectric properties: er = 20.5, Q × f = 91000, and τf = -65 ppm/°C when sintered at 1030 °C for x = 0.2, which provides an alternative material for LTCC technology and an effective approach for low-temperature sintering of Nb-based microwave dielectric ceramics.

New single Crystal of L-Tyrosine Magnesium Chloride (LTMC) was grown from aqueous solution by slow evaporation solution technique (SEST). The grown crystal was subjected to single crystal X-ray diffraction study which confirms that the grown crystal is orthorhombic system with the space group Pmn21. The grown crystals were characterized by Fourier Transform Infrared (FTIR) spectroscopic analysis to find the different modes of vibration due to various functional groups present in LTMC. The transmission spectrum of LTMC was recorded by UV–Vis spectrometer in the range between 200 nm and 800 nm which addressed the grown crystal has good optical transparency in the entire visible region and its energy band gap was determined. The thermal stability of the crystal was determined from thermo gravimetric and differential thermo analysis (TG-DTA) curve. The dielectric constant and dielectric loss has been studied as a function of frequency for various temperatures and the results were discussed in details. The frequency dependence of AC/DC conductivity studies for different temperature was carried out. The photoconductive behavior of the material is also investigated and the grown crystal has positive photoconductive nature. Mechanical strength of the grown crystal was estimated by using Vicker’s hardness test. The presence of second harmonic generation (SHG) for the grown crystal was confirmed by Kurtz Perry powder technique. All these studies indicate that the LTMC crystal can be considered as a potential candidate for the fabrication of optoelectronic devices.

An improved technique was used to prepare the ceramic samples of Bi5.75R0.25Fe1.4Ni0.6Ti3O18 (BRFNT, R = Eu, Sm, Nd, Bi, and La). The five-layer Aurivillius phase of the samples was confirmed by X-ray diffraction (XRD) without detectable impurities. BRFNT samples exhibit the pseudo-tetragonal except the orthorhombic BSmFNT samples. The characteristic plate-like morphology was revealed by field emission transmission electron microscopy (FETEM) images. At ambient temperature, all the samples present both ferroelectric and magnetic properties and BEuFNT shows the best ferroelectric behavior with its remanent polarization as high as 14.9 μC/cm2 under 155 kV/cm, which is three times higher than that of Bi6Fe1.4Ni0.6Ti3O18. Moreover, the remanent magnetization of BEuFNT is increased up to 1.20 emu/g compared to that of Bi6Fe1.4Ni0.6Ti3O18 which is only 0.53 emu/g. With increasing radius of the introduced A-site ions, the ferroelectric phase transition temperature (TCE) is decreased while the magnetic phase transition temperature (TCM) fluctuates. The decrease in both TCE and TCM corresponds to the upward shift of the related Raman modes and vice versa, indicating that the TCE and the TCM depend not only on the t factor, but also on the strength of the covalent bonds.

A new type of microwave dielectric ceramics with low dielectric loss was fabricated through a traditional solid-phase method. X-ray diffraction and density tests showed that KSrPO4 ceramics with a single orthorhombic phase could be synthesized and densified at 950 °C, and the crystal structure of KSrPO4 was further confirmed by Rietveld refinement analysis. The densification temperature of KSrPO4 was lower than 961 °C, indicating the ceramics could be used in LTCC devices. Additionally, based on the complex chemical bond theory, some internal parameters of KSrPO4 ceramics were calculated and the effects of these parameters on the properties of KSrPO4 were systematically analyzed for the first time. Furthermore, the composite dielectric constant and loss of KSrPO4 ceramics were analyzed by infrared reflectance spectroscopy, and the theoretical loss and the actual loss were compared. Finally, a vector network analyzer was employed to measure the microwave dielectric properties of all samples. The results showed that KSrPO4 sintered at 950 °C obtain the best microwave dielectric properties, including er = 7.85, Q·f = 34,527 GHz (at 10.43 GHz) and τf = −14.82 ppm/°C.

Semiorganic single crystals of L-Threonine Lithium Chloride were wealthy developed by slow evaporation method at ambient circumstances. The structure was illuminated by single crystal XRD technique and the structure be owned by orthorhombic system. Density functional theory computations using B3LYP/6-311++ G(d,p) base set gives optimized structural parameters of title compound. The Theoretically identified hyperconjugative molecular interactions are accountable for the stabilization of compound are obtain by NBO analysis. Besides, Mulliken atomic charges and molecular electrostatic potential were also executed.

Screening of AgNO3/AgStBu solutions in DMF, DMSO and NMP resulted in an isolation of three novel nanosized silver/thiolate complexes with a torus-like {Ag20(StBu)10} core. The structures of [NO3@Ag20(StBu)10(NO3)9(DMF)6] (1) and [NO3@Ag20(tBuS)10(NO3)8(NMP)8][NO3@Ag19(tBuS)10(NO3)8(NMP)6]2(NO3) (2) were studied by SCXRD. The self-assembly process leading to 1 can be switched to a different outcome by Br–, resulting in [Br@Ag16(StBu)8(NO3)5(DMF)3](NO3)2 (3), which is the one of the few genuine host-guest complex in the silver/thiolate systems. Solutions of the individual complexes in CH3CN were studied by HR-ESI-MS techniques, which revealed a dynamic behavior for each complex, driven by a redistribution of the {AgNO3} units. This dynamics results in the appearance of both cationic and anionic species, based on unchanged silver-thiolate cores. Day light causes degradation of 3 with the formation of a composite material based on defective orthorhombic Ag2S with a porous morfology, as observed with SEM technique. Electrocatalytic HER activity of such material was studied.

An inorganic compound of sodium magnesium tetrachloride (SMGTC) single crystal was effectively grown by slow evaporation technique at room temperature. The powder X-ray diffraction analysis indicated the crystalline nature of the grown SMGTC crystal. The unit cell parameters were determined by single crystal X-ray diffraction analysis which shows that the SMGTC crystal crystallizes in orthorhombic crystal system with non-centrosymmetric space group Pba2. The UV cutoff wavelength of SMGTC was found to be 234 nm from UV–Vis-NIR studies. The second harmonic generation (SHG) efficiency of the SMGTC crystal was found to be 1.29 times greater than the well known KDP crystal. Presence of metal ion was identified by EDAX spectrum.

Current report is based on the synthesis of Gd+3 doped V2O5 nanostructures (GVO) along with fabrication of GVO/MXene binary nanocomposite. As synthesized GVO and GVO/MXene were characterized by XRD (X-ray diffraction), FESEM (Field emission scanning electron microscopy), EDX (Energy dispersive X-ray), BET (Brunauer Emmett Teller technique) and UV–Visible spectroscopy. Diffraction and elemental analysis confirmed the substitution of Gd+3 ions in VO layers. Orthorhombic phase of VO was observed in both GVO and GVO/MXene samples with crystallite size range of 17.02–17.51 nm. FESEM analysis indicated asymmetrical VO particles and sheets distributed on MXene layers, giving out a sponge like appearance. Surface area of GVO and GVO/MXene was enhanced to 20.46 and 23.69 nm, respectively. Effect of Gd+3 contents was significant on optical properties, which reduced the band gap energy of VO to 2.33 eV. The photocatalytic performance of prepared samples was analysed by the degradation of Methylene blue (MB) under direct sunlight. Gd+3 ion doping was found useful to enhance degradation of MB up to ∼71%. Among all samples, GVO/MXene showed maximum degradation (∼92%) within 120 min. Meanwhile, GVO/MXene showed good recyclability for successive five cycles. In addition, GVO and GVO/MXene were effective antibacterial agents against Gram positive (S. aureus) and Gram negative (P. vulgaris) strains of bacteria. The results suggested that the GVO and GVO/MXene could serve as potential candidates for large scale treatment of organic pollutants and pathogens.

Recently, there has been increasing interest in the synthesis and use of refractory oxide ceramics as a high-temperature electrode and also thermo-electric materials. These materials, such as perovskite type oxides, particularly, compounds like lanthanum chromite LaCrO3, usually exhibit hopping-type electrical conductivities approaching 30(Ω.cm)-1. The present work aims to synthesize and characterize rare-earth chromite oxides RECrO3 (RE: La, Yb, Gd, Pr), which have the orthorhombic perovskite structure that is apparently stable at 1000 °C calcination temperature. The synthesis of RECrO3 (RE: La, Yb, Gd, Pr) compounds was made by a citrate gel process, using rare-earth-nitrate salts as cation precursors, and followed by a heat-treatment at various temperatures (400 °C, 600 °C, 800 °C, and 1000 °C) for 4 h. The obtained powders were characterized by X-Ray diffraction (XRD), and scanning electron microscopy (SEM). Results show that all the products, especially calcined at 1000 °C have a high purity degree and good crystallinity and that this latter increases with the calcination temperature increasing which has “in contrast” a great effect on the agglomeration of the powders as is shown in the SEM’s micrographs.

A series of high-k Ba4Nd28/3Ti18-yGa4y/3O54 (0≤y≤2, BNTG) ceramics with temperature stable and ultra-low dielectric loss were synthesized via the conventional solid-state reaction. The main phase of all BNTG ceramics demonstrated an orthorhombic tungsten-bronze structure, but the impurity phase (gallium-rich phase) was found in BNTG (y = 2) ceramic. Partial substitution of Ga3+ for Ti4+ in B-site was a valid method to improve the temperature stability and dielectric loss of BNTG ceramics. The variation of er values of BNTG ceramics was dominated by the ionic polarizability. The ultra-low dielectric loss (ultra-high Q × f values) was associated with grain size, suppression of Ti3+ and impurity phase. The decrease of TCF values was highly dependent on the tilting of Ti-O octahedra and impurity phase. Finally, outstanding combination dielectric characteristics were achieved for BNTG microwave ceramics at y = 1.5 (er = 72.8, Q × f = 14,600 GHz, TCF=+4.1 ppm/°C) and at y = 2 (er = 70.3, Q × f = 15,500 GHz, TCF=+3.9 ppm/°C).

Perovskite lattice was tailored by introducing site vacancies and mixed anion composition, to produce Sr0.83Li0.17Ta0.83O1.88N0.74 (Li02N). Further, Li02N was converted to a defect oxide Sr0.83Li0.17Ta0.83O3 (Li02O) by applying an optimized treatment: heating in air at 1173 K for 2 h. According to the neutron Rietveld refinement, Li02N and Li02O are tetragonal and orthorhombic, respectively, where the lattice volume of Li02O is significantly smaller than that of Li02N. The ionic conductivity (σion) of Li02N and Li02O was evaluated by the ac impedance spectroscopy and the equivalent circuit analysis. Both Li02N (σion = 10−5.5 S/cm at 671 K) and Li02O (σion = 10−6.2 S/cm at 667 K) exhibited an Arrhenius behavior of ionic conductivity with activation energies of 0.87 eV and 0.75 eV, respectively. It is interpreted that the nitride component enhances the ionic conduction of Li02N, while the vacancy of the anion lattice makes an opposite effect.

A series of BaBi2-xNb2ErxO9 ceramic compositions with different Er3+ concentration (x = 0.0–8 mol %) is synthesized by a conventional solid-state reaction method. The upconversion (UC) light emission under 980 nm excitation with different pump powers and luminescence-based temperature sensing ability of BaBi2-xNb2ErxO9 composition have been examined. The formation of a Bi-layered perovskite phase of BaBi2Nb2O9 is confirmed having an orthorhombic geometry and Fmmm space group. Shifts in the Raman modes indicate reduced interaction of Bi3+ ions with NbO6 octahedron leading to relaxation of structural distortion with increasing Er3+ content. The maximum value for remnant polarization and coercive field of doped BaBi2-xNb2ErxO9 ceramic for (x = 0.08) Erbium concentration comes out to be 2.9524 μC/cm2 and 49.8980 kV/cm. For an optimum content of x = 0.04, two strong UC green emission bands were observed at 549 nm via 4S3/2 → 4I15/2 transition and 527 nm via 2H11/2 → 4I15/2 transitions, and a weak red emission appears at 657 nm attributed to the 4F9/2 → 4I15/2 transition. Pump power dependence suggests that UC emission is a two-photon mechanism for red and green emission bands. Temperature sensing evaluated by the change in the fluorescence intensity ratio (I527/I549) indicates the highest sensitivity to be 0.00996 K−1 at 483 K for an optimum concentration of Er3+ at x = 0.04 in BaBi2-xNb2ErxO9 composition and is useful for non-contact optical thermometry.

Composite Bi5Ti3FeO15 (BTFO) and manganite-based La0.67Sr0.33MnO3 (LSMO) is prepared by the following sol-gel precursor hybrid technique in order to study the magnetodielectric (MD) properties. The coexistence of dual phases of BTFO (orthorhombic) and LSMO (rhombohedral) is confirmed from the Rietveld refinement of the X-ray diffraction (XRD) pattern. The microstructural analysis is carried out using the field-emission scanning electron microscope (FESEM), suggesting the formation of inhomogeneous distribution of both large and small grains of size 586 nm and 261 nm. In addition to the crystallite size calculation, the formation of strain is calculated using the uniform deformation model (UDM). Temperature-dependent dielectric constant and loss responses subjected to a constant magnetic field confirm the existence of the MD effect. The maximum magnitude of the MD effect at room temperature is found to be ~0.17% at a magnetic field of 1.3 T. The behavior of MD effect arises due to the presence of magnetoresistance (MR) in the core of the manganite-based composite material.

Present paper reports the study of single crystal X-ray diffraction of the compound 4-Amino-N-(3-chloropyrazin-2yl)benzene-1-sulfonamide which crystallizes in an orthorhombic crystal system with the space group Pbca having precise unit cell parameters a = 11.5260(19)A, b = 9.6270(16)A, c = 22.099(5)A, Z = 8 and V = 2452.1(8)A3. The structure was solved by direct methods and was refined by full-matrix least-squares based on F2. After subsequent cycles of refinement, the structure was converges to the Goodness-of-Fit (S) = 1.33. The molecule was adopted as a non-planar structure with a dihedral angle of 89.95°. In the crystal, molecules are held together through intermolecular N–H…O and C–H…O interactions. The nitrogen (N) atom of pyrazine ring has exhibited trifurcated intramolecular relations through C–H…N, N…C, and N…O incorporating S(5), S(6), and S(7) ring motifs, respectively. The intermolecular interactions were analyzed, and their percentage of contribution towards crystal packing was computed using Hirshfeld surface analysis. Also, interaction energies between the different pairs of molecules were analyzed, visualized and estimated using the energy density model of B3LYP/6-31G(d,p).

Since the breakthrough findings of Goodenough et al. in 1997, extensive research was carried out on olivine-type LiMPO4 (M: Transition metal) cathode materials for lithium ion batteries. This study reports the synthesis of five compounds LiFe1-xMnxPO4 (x = 0, 0.4, 0.6, 0.65, and 1) using sol–gel method at 800 °C. The crystal structure and the electrochemical properties of LiFe1-xMnxPO4 versus Li+/ Li were investigated. LiFe1-xMnxPO4 materials crystallize in the orthorhombic system with Pnma as space group. Moreover, a slight increase in the cell volume was noticed with the increasing amounts of Mn due to its large ionic radii (where Fe2+ ions (0.78 A) and Mn2+ ions (0.80 A). LiFe0.4Mn0.6PO4 shows the best electrochemical performances delivering a reversible discharge capacity of 110 mAh g−1 for 10 cycles at C/20 although no effective carbon coating was performed on the particles of this phosphate.

In the present study, copper (II) complex of 4, 4′-di-tert-butyl-2,2′-bipyridine [Cu (C18H24N2) (NO3)2], 1 is investigated through its synthesis and characterization using elemental analysis technique, infra-red spectroscopy, and single-crystal analysis. The compound 1 crystallizes in orthorhombic space group P212121. The copper atom in the mononuclear complex is hexa coordinated through two nitrogen and four oxygen atoms from bipyridine ligand and nitrate ligands. The thermal analysis depicts the stability of the entitled compound up to 170 °C, and the decomposition takes place in different steps between 170 and 1000 °C. Furthermore, quantum chemical techniques are used to study optoelectronic, nonlinear optical, and therapeutic bioactivity. The values of isotropic and anisotropic linear polarizabilities of compound 1 are calculated as 41.65 × 10−24 and 23.02 × 10−24 esu, respectively. Likewise, the static hyperpolarizability is calculated as 47.92 × 10−36 esu using M06 functional compared with para-nitroaniline (p-NA) and found several times larger than p-NA. Furthermore, the antiviral potential of compound 1 is studied using molecular docking technique where intermolecular interactions are checked between the entitled compound and two crucial proteins of SARS-CoV-2 (COVID-19). Our investigation indicated that compound 1 interacts more vigorously to spike protein than main protease (MPro) due to its better binding energy of −9.60 kcal/mol compared with −9.10 kcal/mol of MPro. Our current study anticipated that the above-entitled coordination complexes could be potential candidates for optoelectronic properties and their biological activity.

Introduction of artificial pinning centres in different morphology is a beneficial way to improve the flux pinning properties of a YBCO compound. In the present study, we report the effect of addition of sodium niobate (NaNbO3) nanostructures in two different form i.e. nanorods (NRs) and nanoparticles (NPs) with a varied wt% (0, 0.5, and 1 wt%) on the pinning capabilities of bulk YBCO polycrystalline samples. The orthorhombic crystal structure of YBCO was confirmed by the XRD spectra even in the nanocomposite samples. The existence of NPs or NRs on the surface and between the superconducting grains of YBCO was confirmed by morphological analysis. The critical temperature (Tc) remains almost unchanged as compared to pure YBCO on addition of NaNbO3 nanostructure in YBCO compound upto 1 wt% concentration. Even at higher fields (upto 6 T) and higher temperatures (upto 75 K), the addition of NaNbO3 NPs or NRs in YBCO nanocomposite resulted in a significant increase of ~2.6 times in the critical current density as compared to pure YBCO. In comparison to NRs added YBCO nanocomposite samples, NPs added YBCO nanocomposite samples showed higher improvement. Throughout the entire investigated range of applied field, the maximum pinning force was found for 0.5 wt% NPs added composite sample.

This work compares the dielectric properties of two new materials. One was 0.88 bismuth manganite–0.12 lead titanate (noted BM–PT hereafter) ceramics composite obtained by standard high-temperature sintering. The second composite was obtained from powdered ceramics dispersed in epoxy glue (noted BM–PT–epoxy). The occurrence of four phases in the ceramics, using X-ray powder diffraction (XRD), was recognized: orthorhombic Pbam, cubic Pn 3 ‾ m, cubic Pm 3 ‾ m, and monoclinic P2/m phase. Pseudo-Voigt function fitting confirmed significant structural disorder in the BiMn2O5 crystal lattice. Analysis of broadband dielectric spectroscopy data confirmed the applicability of the small polaron model to explain detected relaxation processes. Involvement of oxygen vacancies in relaxation and their correspondence to ordered, uniform potential wells in crystal lattices was deduced. Electric conductivity relaxation times behavior proved the sensitivity of the ceramics’ electrical features to hydrostatic pressure. BM–PT–epoxy composite exhibited dielectric permittivity and losses two orders of magnitude lower than those of BM–PT ceramics that opened new prospects to application. One relaxation process in BM–PT–epoxy composite related to the ceramics fill contribution. Other induced relaxation, observed only in this composite, was attributed to interactions at interfaces between the introduced powdered ceramics and the epoxy glue matrix. We showed that stresses generated either by hydrostatic pressure or through the interfacial interaction of epoxy matrix led to the same results: relaxation times shortening.

Solid polymer electrolytes have been broadly studied due to their wide applications in various electrochemical devices. In the present work, the electrical properties of polyaniline and its composites with BaSO4 have been studied. The polymerization of aniline monomer via the ordinary chemical polymerization process showed an amorphous structure. Whereas, in the presence of BaSO4 as a seed, the aniline is polymerized in an orthorhombic crystalline structure on the BaSO4-surface. Two composite samples of PANI and BaSO4 with different amounts of BaSO4 (1.5 and 2.5 wt%) were prepared and analyzed using XRD, FT-IR, SEM, and XPS techniques. The ac- electrical studies on the composites showed an enhancement in the electrical conductivity of PANI due to the addition of BaSO4. Ac- conductivity at frequency 500 kHz, and 100 °C, showed values of 1.9 × 10−3, 5.4 × 10−4, 1.6 × 10−1, and 1.9 × 10−1 S/cm for PANI, BaSO4, BaSO4/PANI 1.5 wt%, and BaSO4/PANI 2.5 wt%, respectively.

In the current report, pure V2O5, a series of Gd doped V2O5 (1 wt%, 3 wt%, 5 wt% and 10 wt%) and graphene integrated Gd–V2O5 photocatalysts have been prepared using a facile wet chemical approach. The effect of Gd+3 ions substitution and RGO support on V2O5 was studied by the different analytical techniques. X-ray diffraction (XRD) results showed the orthorhombic crystal structure of synthesized samples with crystallize size in range of 22–35 nm. Morphological analysis showed nanorods and nanorod arrays like appearance of V2O5, Gd–V2O5 and GdV-2O5/RGO, respectively. Gd–V2O5 and Gd–V2O5/RGO exhibited enhanced optical response in the visible region along with decrease in the band gap values for Gd doped V2O5 samples. BET surface area of Gd–V2O5 and Gd- V2O5/RGO was calculated as 12.39 g/m2 and 15.35 g/m2 that was found to be higher than pristine V2O5. To study the photocatalytic activity of synthesized photocatalysts, methylene blue (MB) was chosen as model pollutant. Among the Gd doped V2O5 samples, highest photocatalytic activity (45.62%) was achieved by optimal concentration of 5 wt% Gd–V2O5 that is accredited to effective separation of electron-hole pairs. While Gd–V2O5/RGO showed 2.1 times higher dye removal (97.12%) than unsupported Gd–V2O5, under the visible light irradiation. The significantly high photocatalytic activity of Gd–V2O5/RGO is due to the synergistic effect aroused by combined action of Gd+3 ions doping and advantageous properties of highly conductive and large surfaced graphene. Recycling experiments for V2O5 derivatives showed good stability and recyclability of photocatalysts. Additionally, Gd–V2O5/RGO was found to be more potential anti-bacterial agent than V2O5 and Gd–V2O5.

Europium doped (0.1% and 1%) chloroborate BaO–B2O3–BaCl2 glass and glass-ceramic with embedded BaCl2 nanocrystals have been synthesised, investigated, and compared with the corresponding nanocrystalline powder. The structural analysis of the glass evidenced ionic bonds characteristic to the glass host structure and compositional changes during the melting. X-ray diffraction and transmission electron microscopy revealed the formation of orthorhombic BaCl2 nanocrystals of about tens on nm in size and a smaller amount of BaB2O4 nanocrystals. Structural analysis of the Eu2+-doped BaCl2 nanocrystals has shown a distortion of the crystalline cell assigned to the growth process, affected by defects and ionic impurities. Photoluminescence spectra of the glass-ceramic revealed Eu3+ and Eu2+ luminescent ion species, but only Eu2+ is incorporated within the BaCl2 nanocrystalline phase. Electron paramagnetic resonance measurements in X-band sustain the presence of Eu2+ ions. The EPR parameters (g values and hyperfine constants) resulting from the Q-band EPR spectra simulations recorded on glass-ceramic are similar to those in Eu2+-doped BaCl2 and confirmed the partial incorporation of Eu2+ ions within the BaCl2:Eu2+ nanocrystals in the glass-ceramics.

The moisture resistance of 5 mol% Nd2BaCuO5-added Nd1+xBa2−xCu3Oy (x = 0–0.8) ceramics was investigated. The samples were prepared by a solid-state reaction at 980 °C and exposed to a humid atmosphere at 40 °C and 93 %RH. The microstructure observation and X-ray diffraction measurement of the exposed samples revealed that the surface morphology and the crystal structure tended to be more stable when the amount of x was increased. The crystal structure was orthorhombic for x = 0 and tetragonal for x = 0.2–0.8. By comparing the lattice constants calculated by the bond valence to those determined by X-ray diffraction, it was suggested that a gap around the Ba site increased with the increasing x. The gap around the substituted Nd3+ for Ba2+ was considered to act as a trap site for OH−.

Due to the similarity in composition and crystal structure of some TiAlSi ternary intermetallics, it is quite difficult to accurately confirm their physic characteristics, and thus, to tailor microstructure to improve mechanical properties of metal materials related to the TiAlSi intermetallics. Therefore, the formation process of TiAlSi intermetallics was investigated during heating Ti-A356 mixed powder compact at a A356 alloy semisolid temperature of 595 °C. The results indicated that two kinds of intermetallics of τ1 (tetragonal, I41/amd) and τ2 (orthorhombic, Cmcm) generated, and both the concentration and supply direction of Ti atoms, which are related to local breakage of oxide films on neighboring Ti and A356 alloy powders, determined the phase and morphology of the intermetallics. τ1 and τ2 crystals all had an intrinsic plate morphology, but τ2 crystals were thinner due to more anisotropic growth resulted from their high density of stacking faults (SFs). τ1 lamellar domains generated during growth of τ2 crystals, which were accompanied by decrease in density of SFs. The combined effect of size difference and internal energy difference between τ1 and τ2 crystals made large τ1 crystals coarsen at the expense of τ2 crystals in Ostwald ripening, leading them to finally evolve into an agglomerate of large τ1 plates.

Crystal lattice structure searching by Particle Swarm Optimization (PSO) and first-principles structural optimization have been used to explore polymorphs of BC2N, possessing sp3 hybridization, under a varying applied hydrostatic pressure. Two low Gibbs free energy structures were identified: one with a primitive orthorhombic structure and Space Group, Pmm2, and the other with a primitive tetragonal structure and Space Group, P m2. Dynamical and mechanical stabilities of the Pmm2, orthorhombic BC2N (o-BC2N) structure were established using its phonon dispersions and elastic constants. The bulk modulus of this predicted BC2N phase was 377.15 GPa, which indicates a super-hard compound. The material is brittle with a B/G ratio of 0.911 and a low degree of elastic anisotropy with a Universal Elastic Anisotropy Index of only 0.774%. Calculations of the electronic band structure demonstrated that the material is a direct band gap semiconductor with a band gap of 1.731 eV at zero applied pressure. The band gap increases monotonically with increased applied pressure and saturates to a value of about 1.756 eV above 1500 kbars; the hydrostatic pressure coefficients associated with this process were determined. Key words: High pressure phase stability, elastic anisotropy, ultra-hard material.

In the current investigation, a series of NaCa1-x PO4 :xDy3+ (x = 0.1, 0.3, 0.5, 0.7, 1.0, 1.5 and 2 mol%) phosphors were synthesized using a solution combustion method and citric acid as fuel. The investigated results from the X-ray diffraction (XRD) pattern showed phase purity of the synthesized material and orthorhombic crystal structure with space group Pna21. Photoluminescence properties of the synthesized phosphors were investigated. The synthesized Dy3+ -activated phosphor displayed blue (482 nm) and yellow (576 nm) emission under near-ultraviolet or blue excitations. These emission bands were ascribed due to the 4 F9/2 →6 H15/2 and 4 F9/2 →6 H13/2 transitions of Dy3+ ions. Commission International de l'Eclairage chromaticity coordinates showed emission in the near-white region for the proposed phosphors under different excitations. In addition, the current-voltage (I-V) characteristics of the NaCa1-x PO4 :xDy3+ (x = 1.5 mol%) phosphor-coated silicon solar cell and an uncoated solar cell were investigated under a solar simulator. The I-V characteristics of the proposed phosphor-coated silicon solar cell showed enhancement in solar cell efficiency by ~7.92%. The entire studies and their outcomes showed that synthesized phosphors have potential as white light emitting diodes and for solar applications.