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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.

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.

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.

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.

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.

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).

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.

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.

Tin (Sn)-doped orthorhombic gallium oxide (κ-Ga2O3) films were grown on (0001) sapphire by mist chemical vapor deposition. It is known that κ-Ga2O3 is more stable than α-Ga2O3 (corundum) but less stable than β-Ga2O3 (monoclinic). This thermodynamic stability means an optimal growth temperature (Tg) of the κ-phase (600-650 °C) is also in between the two. At first, it was observed that Sn doping induced the κ-phase during the growth of the β-phase (Tg = 700 °C). Interestingly, Sn could also promote the κ-phase even under the growth condition that strongly favors the α-phase (Tg = 450 °C). The postgrowth annealing tests at 800-1000 °C showed that the thermal stability of the κ-phase depends on the Sn concentration. The higher the Sn concentration, the more stable the phase. The one with the highest Sn content showed no phase transition from κ to β after annealing at 800, 900, and 1000 °C for 30 min each. This enhancement of thermal stability promises more reliable high-power and high-frequency devices for which κ-Ga2O3 is suitable. Although there was no correlation between Sn-induced phase stabilization and the crystal quality, cathodoluminescence revealed that increasing Sn concentration led to the strong suppression of the radiative recombination at 340 nm from the vacancy-related donor-acceptor pairs. This observation suggests that the phase stabilization by Sn could be related to a specific Ga site Sn replaces in the orthorhombic structure.

Optimization of materials exhibiting high-temperature superconductivity for producing controllable nano-devices is crucial for industrial applications. Herein we report a comprehensive study of the diffusion process between YBa2Cu3O7−δ (YBCO) and iron particles. Fe diffusion into the YBCO matrix could be fundamental for multilayer systems with YBCO/Fe-alloy interfaces. We have found that the orthorhombic YBCO structure adopts to 3 wt% Fe, while for higher Fe content, a formation of BaFeO3−δ and iron oxides was observed. Complementary measurements confirmed the strong superconductivity suppression in YBCO-Fe materials containing more than 7 wt% Fe. The YBCO with diffused Fe material retain the unit cell orthorhombicity (max. 3 wt% Fe), and their superconducting properties follow the principle of critical scaling with different exponents (γ). The critical current density (Jc), pinning fields (HP) exhibit γ = 1, the first critical field (Hc1) shows γ = 1/2, and critical temperature (Tc) demonstrates γ = 7/4.

LiCoPO4 is an attractive cathode material, but it undergoes poor electronic conductivity and electrochemical performance. This performance is enhanced by substituting iron antisite Cobalt to reduce the direct interaction between the cathode and the electrolyte. Thus, LiCoPO4 doped with Fe was synthesized by the microwave-assisted solvothermal route at 220 °C. According to X-ray diffraction analysis, a single orthorhombic Pn21a phase (a = 10.02 A, b = 6.71 A and c = 4.96 A) was obtained, which transited to Pnma phase (a = 10.21 A b = 5.92 A and c = 4.76 A) after annealing at 700 °C in air. The morphology and particle size of the sample changed after annealing, as shown by TEM. The electrochemical cycling of an annealed sample showed the initial discharge capacity of 125mAh g−1 compared to 12 mAh g−1 for the non-annealed sample, which can be regarded as a partial coating by FePO4 as obtained from X-ray absorption spectroscopy analysis.

We present a study on the structural and phonon properties of cobalt-doped orthorhombic molybdenum trioxide (α-MoO3:xCo) hierarchical microrods. The samples were synthesized by solid-state reaction with molar concentrations of 0%, 1%, 3%, and, 5% cobalt. X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and Fourier transformed infrared spectroscopy (FTIR) were used to confirm the orthorhombic phase and the structural properties of each sample. The infrared and Raman spectra of the samples show that doping alters the ratio of relative intensities, linewidth, and the shift of the wavenumber of the modes, and a correlation is established between the stretching force constant and wavenumber. Experimental temperature-dependent Raman scattering studies were performed on samples of α-MoO3:xCo over a temperature range of 298–813 K. The Raman spectra showed a phase transition at around 373 K to a self-similar structure, indicating a possible isostructural phase transition (IPT) for samples with 0% and 1% cobalt, a phenomenon rarely reported in the literature. Nevertheless, this phase transition was not observed for samples containing 3% and 5% cobalt, indicating an increase in material stability.

The volatization of cesium at high temperatures makes its immobilization challenging to the nuclear scientists. Present work reports the feasibility of cesium incorporation into an orthorhombic langbeinite phosphosilicate. The structural flexibility, leachability and thermal expansion of K2-xCsxZr2P2SiO12 (x = 0, 0.5, 1.0, 1.5, 2.0) have been investigated. Powder X-ray results authenticates the accommodation of cesium into a single phasic orthorhombic langbeinite structure up to 29.17 wt %. Morphological study reveals the particle agglomeration and poor crystallinity, and vibrational spectral analysis shows peak broadening and peak shift upon increasing the cesium concentration. The static leach test has been performed on the pellet sample and the normalized leaching of Cs is found to be in the order of 101 g/m2. The average coefficient of thermal expansion for K0.5Cs1.5Zr2P2SiO12 is registered as 7.45 × 10−6/K between 303 and 873 K. Cesium insertion into K2Zr2P2SiO12 displays a large deviation in thermal expansion due to the size effect as observed by several researchers for other phosphate and phosphosilicate members.

The crystal and electronic structure properties of Ni-B (nickel-boron) alloy coatings produced by an electrodeposition method have been investigated. The crystal structures of the alloy coatings were determined by x-ray diffraction patterns and supported by extended x-ray absorption fine structure (EXAFS) spectroscopy. The local atomic structure around the Ni atom was obtained from EXAFS studies at the Ni K-edge, and the EXAFS data were fitted with theoretical calculations. With the addition of boron atoms in the nickel environment, NiB composite alloys were formed in the crystals with an orthorhombic "Cmcm" structure. The analysis revealed a limited effect of boron doping in the electronic structure of the nickel atoms. Boron atoms were determined as sitting between the Ni atoms and causing a disturbance in the crystal structure due to providing inhomogeneous interstitial potential and defects.

Two alkali tin(II) phosphates, namely, Rb[SnF(HPO4)] and Rb(Sn3O)2(PO4)3, were synthesized through mild hydrothermal methods. They belong to the orthorhombic Pnma and Pbcn space groups, respectively. Rb[SnF(HPO4)] features a layered structure based on 1D [SnF(HPO4)]∞ chains interconnected by hydrogen bonds, with Rb+ cations located at the interlayer space. For Rb(Sn3O)2(PO4)3, each pair of [Sn3O]4+ clusters is bridged by a pair of [P(1)O4]3- tetrahedra to build a 1D [Sn-P-O]∞ chain. These 1D [Sn-P-O]∞ chains are further cross-linked though [P(2)O4]3- tetrahedra to construct a 3D network with 7- and 10-membered-ring channels. The tin(II) ions in Rb[SnF(HPO4)] and Rb(Sn3O)2(PO4)3 with stereochemically active lone pairs (SCALPs) significantly enhance the birefringences of metal phosphates: Δn = 0.147@1064 nm for Rb[SnF(HPO4)] and 0.082@1064 nm for Rb(Sn3O)2(PO4)3.

We have synthesized the orthocarbonate Sr3[CO4]O in a laser-heated diamond anvil cell at 20 and 30 GPa by heating to ≈3000 (300) K. Afterward, we recovered the orthocarbonate with [CO4]4- groups at ambient conditions. Single-crystal diffraction shows the presence of [CO4]4- groups, i.e., sp3-hybridized carbon tetrahedrally coordinated by covalently bound oxygen atoms. The [CO4]4- tetrahedra are located in a cage formed by corner-sharing OSr6 octahedra, i.e., octahedra with oxygen as a central ion, forming an antiperovskite-type structure. At high pressures, the octahedra are nearly ideal and slightly rotated. The high-pressure phase is tetragonal (I4/mcm). Upon pressure release, there is a phase transition with a symmetry lowering to an orthorhombic phase (Pnma), where the octahedra tilt and deform slightly.

The colored non-toxic near-infrared (NIR) reflective and infrared radiative pigments are desired in reducing the energy consumption of buildings. In this work, yttrium ferrite (YFeO3) pigments with controllable crystalline structure were successfully synthesized via the method of solid-state reaction at low-heating temperature. The effects of the crystalline structure and microstructure, especially charge state distribution, on the bandgap, chromatic properties, infrared reflection and radiation performance of YFeO3 pigments were investigated for the first time. With the calcining temperature increased, the structure of obtained pigments changed from hexagonal to orthorhombic, and the bandgap was obviously widened. The black hexagonal YFeO3 pigments possessed small particle size, and their intensive optical absorption in the NIR range was related to the noticeable multiple reflections induced by the grain boundary. While, the brown orthorhombic YFeO3 powdered pigments, as well as the corresponding pigmented coatings, possessed good NIR reflection characteristics, and the high solar reflectance values clearly highlight the potential of these pigments as cool pigments. In addition, the obtained YFeO3 pigmented coatings showed high emissivity in 8–14 μm waveband (atmospheric window), indicating their potential applications in energy saving of buildings by combining NIR shielding and space cooling. The larger amount of Fe2+-Fe3+ ions pairs in the orthorhombic pigments led to the enhancement of free carrier absorption, which enhanced infrared emission and contributed to the slightly decreased NIR reflectance.

Nb2O5–TiO2 nanomaterials containing 0.5 and 10 mol % TiO2 have been synthesized by the programmed deposition method. The products have been characterized by modern physicochemical methods The Nb2O5–TiO2 nanomaterials have a crystal structure of orthorhombic Nb2O5 (T-phase). Individual niobium oxide is composed of nanoparticles with an average size of 15 ± 3 nm; increasing the TiO2 content entails microstructural changes. For the Nb2O5–TiO2 coatings, a set of chemoresistive gas-sensing properties has been studied. Of all the analyzed gases, the highest sensitivity was recorded for oxygen and hydrogen sulfide. It has been shown that the sample with 5% TiO2 is most sensitive to О2 and H2S, which is explained by the formation of additional oxygen vacancies.

Because of their particular characteristics, searching for potential sp2–sp3 hybridized carbon allotropes has become the foundation of new functional materials in the future. Here, we design a novel carbon phase constructed by sp2–sp3 hybridized bonding networks with a 36-atom body-centered orthorhombic unit cell, termed oC36. oC36 shows thermodynamic stability comparable to most of the theoretically predicted sp3 carbons. The elastic and dynamical stability of oC36 is confirmed by the calculation results of elastic constants and phonon spectra. Analysis of electronic properties reveals that oC36 changes from semiconductivity to one-dimensional conductivity with external pressure exceeding approximately 4 GPa. The conductivity arises from the overlap of the valance and conduction bands owing to sp2 hybridized nonbonding carbon interactions as the lattice constant decreases. Electron–phonon coupling calculations indicate the superconductivity of oC36 under 25 GPa, and its λ and TC values are 0.50 and 10.7 K, respectively. Strikingly, the estimated hardness, tensile strength, and shear strength of oC36 reach remarkably high values of 69.5, 79.1, and 78.9 GPa, respectively, indicating its superhardness and ultra-incompressibility. Our research expands the scope of sp2–sp3 carbon allotropes and provides new ideas for the later theoretical design of carbon allotropes with switchable properties.

We synthesized single crystals of marokite (CaMn2O4)-type orthorhombic manganese (II,III) oxide, γ-Mn3O4, in a multianvil apparatus at pressures of 10-24 GPa. The magnetic, electronic, and optical properties of the crystals were investigated at ambient pressure. It was found that γ-Mn3O4 is a semiconductor with an indirect band gap Eg of 0.96 eV and two antiferromagnetic transitions (TN) at ∼200 and ∼55 K. The phase stability of the γ-Mn3O4 crystals was examined in the pressure range of 0-60 GPa using single-crystal X-ray diffraction and Raman spectroscopy. A bulk modulus of γ-Mn3O4 was determined to be B0 = 235.3(2) GPa with B' = 2.6(6). The γ-Mn3O4 phase persisted over the whole pressure range studied and did not transform or decompose upon laser heating of the sample to ∼3500 K at 60 GPa. This result seems surprising, given the high-pressure structural diversity of iron oxides with similar stoichiometries. With an increase in pressure, the degree of distortion of MnO6 polyhedra decreased. Furthermore, there are signs indicating a limited charge transfer between the Mn3+ ions in the octahedra and the Mn2+ ions in the trigonal prisms. Our results demonstrate that the high-pressure behavior of the structural, electronic, and chemical properties of manganese oxides strongly differs from that of iron oxides with similar stoichiometries.

Three new alkali-metal manganese fluoride selenates, A2Mn(SeO4)F3 (A = K, Rb, Cs), were prepared through hydrothermal redox reactions. The products consisted of one-dimensional polymeric anionic ∞[Mn(SeO4)F3]2- chains, where the A+ cations are connected by O and/or F atoms to form blocks with two-dimensional layers. A2Mn(SeO4)F3 (A= Rb, Cs) is isostructural with the monoclinic space group P21/c, while K2Mn(SeO4)F3 crystallizes in the orthorhombic space group Pbcn. A2Mn(SeO4)F3 (A = K, Rb, Cs) forms spin chains of Mn3+ with different Mn-F-Mn bridges, which showed canting antiferromagnetic behaviors. Single-crystal magnetic measurements revealed that the magnetic moments of the Mn ions were more canted for larger alkali-metal compounds in an antiferromagnetically ordered state.

Tin monosulfide can be grown in cubic (pi-SnS) and orthorhombic (alpha-SnS) polymorphs by low-temperature atomic layer deposition (ALD). The optical properties of these polymorphs make them attractive for the realization of plasmonic solar cells with ultrathin absorber layers down to 10 nm in thickness. SnS is also an earth-abundant and nontoxic compound semiconductor of high interest for regular thin-film photovoltaics. To better understand the behavior of the two SnS polymorphs in ultrathin solar cell configurations, we here fabricate, characterize, and analyze a range of such devices. ALD is used to grow SnS and form heterojunctions with zinc oxysulfide [Zn(O,S)], acting as a buffer layer with a composition-tunable bandgap. Apart from the roles of the SnS polymorph and Zn(O,S) composition, the effects of the back contact material and thicknesses of buffer and absorber layers are investigated. Devices using pi-SnS and pure ZnO buffers yield the highest photocurrents (3.1 mA/cm(2)) and higher open circuit voltage (159 mV) than similar alpha-SnS-based devices. Analysis of the equivalent-circuit parameters suggests that interface recombination limits the voltage for these devices. While Zn(O,S) with a higher sulfur content provides chemical passivation of the SnS interface and excessive open circuit voltages above 600 mV, it also exhibits a too high conduction band offset, which hampers current collection. A growth delay during the ALD of Zn(O,S) on SnS initially amplifies the known sulfur-oxygen exchange reaction, such that a sulfur-rich Zn(O,S) region forms next to the SnS interface. This causes a thin ZnS-like barrier to form already for low cycle fractions of the H2S precursor in the ALD super-cycle. Voltage and fill factor trends suggest an optimal SnS absorber layer thickness in the range of 15-35 nm, presenting an opportunity for plasmonic absorption enhancement. Devices with pi-SnS show most promise, but interface recombination versus current-blocking is a dilemma for the SnS/Zn(O,S) heterojunction.

This paper reports the effect of chromium’s substitution in magnetic oxides with perovskite structure La0.5Sm0.2Sr0.3Mn1-xCrxO3 (x = 0, 0.1, 0.15 and 0.2) compounds which have been produced with the glycine-nitrate process (GNP). The four compounds have an orthorhombic crystal structure with ‘Pnma’ space group. We note that they undergo a second-order paramagnetic-ferromagnetic (PM-FM) phase transition. Substitution manganese by chromium leads to a drop of the Curie temperature TC from 278 K (x = 0) to 205 K (x = 0.2). Their magnetocaloric effect has been evaluated by their magnetic entropy change $$\left(-\Delta {S}_{M}^{max}\right)$$ under a magnetic field change up to 5 T. All relative cooling power (RCP) suggests that these compounds are suitable candidates for magnetic refrigeration.

Report on systematic theoretical investigations of the effect of a mixed tin–lead cation strategy on structural, electronic and optical properties of orthorhombic methylammonium lead bromide perovskite using state-of-the-art first-principles calculation based on the hybrid density functional theory method. Our findings reveal that the band gap value of the alloy can be progressively tuned from pristine MAPbBr3 to MASnBr3, showing a quasi-linearly with the Sn concentration. Therefore, the band gap value is reduced from 2.7 eV to 1.58 eV when 75% amounts of Sn are incorporated into perovskite lattice. The improved absorption peaks toward visible region are observed owing to the increased composition of Sn substitutional at Pb in perovskite structures. Moreover, the solar cell performance parameters are also investigated using numerical device simulation. Our simulations show that the efficiencies of mixed Sn-Pb perovskite -based devices are significantly enhanced up to 11% compared with those based on pristine MAPbBr3. This result highlights MAPb0.25Sn0.75Br3 as a promising less toxic absorber for solar cell devices with the greatest simulated efficiency of 23.2%. Our findings suggest that a cation mixing scheme can be explored to tune the stability, band gap, and device performance of perovskite-based materials, which can be notably effective for designing high-efficiency performance of Sn-Pb-based mixed bromide perovskite solar cells.

Oxygen carriers (OCs) with perovskite structure are attracting increasing interests due to their redox tunability by introducing various dopants in the structure. In this study, LaNixFe1-xO3 (x = 0, 0.1, 0.3, 0.5, 0.7, 1.0) perovskite OCs have been prepared by a citric acid–nitrate sol–gel method, characterized by means of X-ray diffraction (XRD) analysis and tested for algae chemical looping gasification in a fixed bed reactor. The effects of perovskite types, OC/biomass mass ratio (O/B), gasification temperature and water injection rate on the gasification performance were investigated. Lower Ni-doped (0 ≤ x ≤ 0.5) perovskites crystalized in the rhombohedra system which was isostructural with LaNiO3, while those with composition 0.5 ≤ x ≤ 1 crystalized in the orthorhombic system. Despite the high reactivity for LaNiO3, LaNi0.5Fe0.5O3 (LN5F5) was found to be more stable at a high temperature and give almost as good results as LaNiO3 in the formation of syngas. The relatively higher syngas yield of 0.833 m3⋯kg−1 biomass was obtained under the O/B of 0.4, water injection rate of 0.3 ml⋯min−1 and gasification temperature at 850 °C. Continuous high yield of syngas was achieved during the first 5 redox cycles, while a slight decrease in the reactivity for LN5F5 after 5 cycles was observed due to the adhesion of small grains occurring on the surface of OCs. However, an obvious improvement in the gasification performance was attained for LN5F5 compared to raw biomass direct gasification, indicating that LN5F5 is a promising functional OC for chemical looping catalytic gasification of biomass.

Y$_{0.9}$Gd$_{0.1}$Fe$_{2}$, which crystallizes in a C15 cubic structure, can absorb up to 5 H/f.u. and its pressure-composition isotherm displays a multiplateau behavior related to the existence of several hydrides with different crystal structures. At room temperature Y$_{0.9}$Gd$_{0.1}$Fe$_{2}$H$_{x}$ hydrides (2.9 $\le$ x $\le$ 5) crystallize in three phases with cubic structure (C1, C2 and C3), two phases with monoclinic structures (M1 and M2), and one phase with orthorhombic structure (O), with the following sequence for increasing H concentration: C1, M1, C2, M2, C3, O. Each phase exists as single phase within a H homogeneity range, and they are separated from each other by two-phase domains. The reductions of crystal symmetry are related to various hydrogen orders into interstitial sites. Weak superstructure peaks were indexed by doubling the cubic cell parameter of the cubic C2 phase. Upon heating, the monoclinic M1 and M2 and the cubic C2 phases undergo order-disorder (O-D) transitions toward a disordered cubic structure CDis. These O-D transitions are reversible with thermal hysteresis effects. The cubic C3 and orthorhombic O phases transform into a disordered cubic phase accompanied by H desorption., 16 pages, 8 figures, 2 tables

A novel and good optical quality NLO single crystal of copper zinc hydrogen phosphate (CuZnHPO4) is grown by gel technique in silica hydrogel media. Both single crystal and powder X-ray diffraction analysis found that the orthorhombic crystal arrangement with space group Pnma and the predictable lattice parameters are a = 10.51 A, b = 18.9 A, c = 5.05 A, and α = β = γ = 905. Thermogravimetric analysis is used to perform this thermal stability of the crystals that have been produced. SEM and TEM images reveal that plate-like morphology and further plate-like growth were observed on some plates. UV spectra results reveal that the absorption of the grown crystal was found in the visible region and suggest that it can be useful for NLO applications. With increasing frequency, both the dielectric constant and the dielectric loss reduced. Moreover, the grown crystal had high conductivity and the activation energy of 0.426 eV. Photoconductivity studies of CuZnHPO4 revealed the positive photoconduction nature of the crystal. Kurtz–Perry powder SHG test was employed to determine the SHG efficiency. The estimated SHG efficiencies are 19.2 mJ and 52.6 mJ for KDP and CuZnHPO4 crystals, respectively. The results suggest that the SHG efficiency of CuZnHPO4 crystal is 2.73 times better than KDP single crystal.

The pressure-induced structural phase transitions in bismuth tungstate Bi2WO6 have been studied using neutron diffraction and Raman spectroscopy at high pressures up to 7 and 30 GPa, respectively. A rich structural polymorphism was revealed. At P ≃ 3.5 GPa a phase transition from the initial orthorhombic phase of P21 ab symmetry to an orthorhombic phase of B2cb symmetry was observed. This transition is caused by the complex spatial rotation of the WO6 octahedra. A subsequent isostructural phase transition to another orthorhombic phase of B2cb symmetry was detected at P ≃ 5.9 GPa, accompanied by changes in both the mutual rotation and tilting of the oxygen octahedra with respect to the crystal b axis. Two more pressure-induced phase transitions in Bi2WO6 at high pressures of 11.5 and 20 GPa were observed in the Raman spectra. These pressure-driven phase transitions in bismuth tungstate are accompanied by anomalies in the pressure dependences of the unit-cell parameters, bond lengths and angles, and in the vibrational modes.

Lanthanum- and zirconium-doped perovskite Ba0.5Sr0.5Fe0.9Cu0.1O3-δ ceramics, i.e., LaBa0.5Sr0.5Fe1.8Cu0.2O6-δ (LBSFC) and Ba0.5Sr0.5Fe0.85Cu0.1Zr0.05O3-δ (BSFCZ), were synthesized and characterized. The characterizations include x-ray diffraction, scanning electron microscopy, x-ray near-edge absorption spectroscopy of the Fe K-edge and Cu K-edge, iodometric titration, and electrical conductivity measurements. The structure of BSFCZ was pseudo-cubic single perovskite, whereas LBSFC was orthorhombic double perovskite. It was also discovered that the iron and copper in the octahedron-site has a mixed oxidation state with iron having 3+/4+ and copper 2+/3+. The ratio of Fe3+/Fe4+ was found to be 59/41 for LBSFC and 75/25 for BSFCZ. Similarly, copper has a mixed Cu2+/Cu3+ = 24/76 for BSFCZ and 44/56 for LBSFC. The unit cell symmetry, the presence of La3+, and the formation of Fe4+/Cu3+ are thought to be responsible for the improvement in the electrical conductivity and performance of the LBSFC. In contrast, the Zr4- stabilized perovskite structure was unfavorable for electrical conductivity. The electrical performance of the LBSFC achieved a maximum conductivity σ = 150 S/cm-1 at 500°C.

Polycrystalline ceramic samples of Mn substituted Yttrium ortho-ferrite have been synthesized using the conventional high temperature solid-state reaction method. X-ray diffraction analysis confirmed the formation of the polycrystalline compound. Rietveld analysis of X-ray diffraction patterns revealed the monophasic orthorhombic structure with space group Pnma. Average crystallite size has been calculated which is showing the decreasing trend with increase of Mn content. The three-dimensional crystal structures have been generated using the Vesta software and different structural parameters have been calculated using these structures. The dielectric measurement as a function of frequency and temperature indicates that the relative permittivity and loss factors are increasing with the increase in substitution concentration. Similarly, the impedance has been measured as a function of frequency and temperature which reflects overall decreasing trend. In all cases the AC conductivity is showing the increasing trend with temperature. Further, the DC conductivity has also been measured and the material constant (B) has been calculated which reflect the NTCR (negative temperature coefficient of resistance) effect for these materials. The I–V characteristic curves recorded at 573 K and 673 K show the enhancement in current and linearity with temperature as well as with substitution concentration.

Bi4–xNdxTi3O12 (x = 0.4, 0.8, 1.2, 1.6) bismuth neodymium titanate solid solutions have been prepared by solid-state reactions, via firing of mixtures of their constituent oxides in air at temperatures from 1003 to 1323 K. The crystal structure of the synthesized phases has been determined by X-ray diffraction. The results demonstrate that increasing the neodymium concentration leads to a morphotropic phase transition from the orthorhombic structure (sp. gr. B2cb) of the parent phase Bi4Ti3O12 (which persists at x = 0.4 and 0.8) to a tetragonal structure (sp. gr. P42/ncm) at x = 1.2 and 1.6. The heat capacity of the synthesized bismuth neodymium titanate samples has been determined by differential scanning calorimetry in the temperature range 320–1000 K. The Cp(T) curves of the Bi4 – xNdxTi3O12 samples with x = 0.4 and 0.8 have been shown to have extrema due to their ferroelectric phase transition.

In order to expand the field of alkali lithosilicates, a new representative of the substance class with a previously unknown structure type was found based on solid‐state synthesis. The novel compound with the sum formula Rb[Li5Si2O7] crystallizes in the orthorhombic space group Pbcm (no. 57) with a=7.6269(3), b=9.5415(4), and c=9.4095(3) Å by means of single‐crystal X‐ray diffraction. The structure consists of a highly condensed lithosilicate framework, built up of corner‐ and edge‐linked [LiO4]‐tetrahedra and [Si2O7]‐units, and the rubidium ions aligned in channels. Suitable crystals of the material were obtained using sealed tantalum ampoules as reaction tube at a temperature of 750 °C. The new compound was further characterized via powder diffraction, Rietveld analysis, and EDX measurements. At first glance, Eu2+‐doped Rb[Li5Si2O7] reveals an intense green luminescence. In‐depth crystal analysis shows that a core‐shell formation is present even for apparently high quality single‐crystals. As a minority phase, the known green phosphor RbLi[Li3SiO4]2:Eu2+ is the origin of the luminescence, representing a tiny core inside of the particles surrounded by a large matrix of transparent Rb[Li5Si2O7] dominating the single‐crystal diffraction pattern., After the rediscovery of alkali lithosilicates as phosphor materials, a new representative has been found. The novel compound with the sum formula Rb[Li5Si2O7] crystallizes in the orthorhombic space group Pbcm (no. 57), exhibiting a new structure type. Eu2+‐doped Rb[Li5Si2O7] feigns an intense green luminescence, in reality co‐crystallizing as a matrix around a tiny core of the known narrow‐band green phosphor RbLi[Li3SiO4]2:Eu2+.

Understanding the microstructure of complex crystal structures is critical for controlling material properties in next-generation devices. Synthetic reports of twinning in bulk and nanostructured crystals with detailed crystallographic characterization are integral for advancing systematic studies of twinning phenomena. Herein, we report a synthetic route to controllably twinned olivine nanoparticles. Microstructural characterization of Fe2GeS4 nanoparticles via electron microscopy (imaging, diffraction, and crystallographic analysis) demonstrates the formation of triplets of twins, or trillings. We establish synthetic control over the particle crystallinity and crystal growth. We describe the geometrical basis for twin formation, hexagonal pseudosymmetry of the orthorhombic lattice, and rank all of the reported olivine compounds according to this favorability to form twins. The work in this study highlights an area ripe for future exploration with respect to the advancement of solution-phase synthetic approaches that can control microstructure in compositionally complex, technologically relevant structures. Finally, we discuss the potential implications for olivine properties and performance in various applications.

A novel MoO3, MoO3/GO, and MoO3/GO/MnO2 ternary nanocomposites have been prepared by hydrothermal technique. The samples are characterized to identify the various performances such as structural, morphological, elemental, and surface area analysis. XRD data reveals that the MoO3 nanoparticles show orthorhombic crystal structures and their miller indices are in good agreement with the standard value (0 2 0), (1 1 0), (0 4 0), and (0 2 1) crystalline planes of MoO3. SEM images show the formation of stacked graphene oxide (GO) and spherical nanocrystallites. The presence of molybdenum (Mo), manganese (Mn), and oxide (O) are confirmed from the EDS spectrum. BET result exposing high surface area with more active sites for redox process of the materials, which giving rise to a better catalytic activity. Electrochemical performances of MoO3/GO/MnO2 ternary nanocomposite exhibited a tiny area of hysteresis, clearly revealing the enhanced specific capacitance of the material. The calculated specific capacitance value is 89.5 F g−1. Thus, the prepared ternary nanocomposites give a gateway for new potential industrial applications.

A novel mononuclear zinc coordination compound with formula [Zn(Hsal)2(Py)2] (H2sal = salicylic acid, Py = pyridine) was prepared by mixing aqueous solutions of sodium salicylate and zinc sulfate in 1:1 molar ratio, and to the resulting solution pyridine was added dropwise. The obtained compound was characterized by elemental analysis, IR spectroscopy, and its crystal structure was determined by single-crystal X-ray diffraction method. X-ray structure analysis has shown that the central zinc ion is four-coordinated by two monodentate salicylato ligands and two pyridine molecules, forming a distorted tetrahedron. Since the asymmetric unit consists of two halves of coordination molecules, orthorhombic Ibca space group symmetry leads to two coordination molecules with slightly different geometry. The comparison between the two is given in terms of interatomic distances and angles, and also in terms of differences in intermolecular interactions obtained as a result of Hirshfeld surface analysis. With the assistance of C−H…O interactions, the adjacent molecules are linked into chains and further connected into three-dimensional network.

Calcium manganites (CaMnO3) ceramic powders were prepared by sol–gel technique using citric acid as a chelating agent. The polycrystalline powder crystallized in an orthorhombic structure with lattice parameters a = 5.270 A, b = 7.421 A and c = 5.231 A. Dielectric relaxation was observed which can be attributed to Maxwell–Wagner relaxation behavior. The oxidation states of Calcium, Manganese and the presence of oxygen deficiencies in the prepared samples were ascertained by XPS studies.

A new intercalation-type anode material is reported herein to improve the lithium storage kinetics for high-rate lithium ion capacitors. The crystal structure of orthorhombic NaNbO3 indicates two possible tunnels for lithium ions insertion into NaNbO3 host along the and directions. Moreover, in situ XRD is conducted to investigate the lithium storage mechanism and structural evolution of the NaNbO3 anode, demonstrating its intercalation behavior through (101) and (141) planes. Furthermore, the rGO nanosheets are introduced to facilitate the charge transfer, which also effectively prevent the aggregation of NaNbO3 nanocubes. As expected, the NaNbO3/rGO nanocomposites possess remarkable reversible capacity (465 mA h g−1 at 0.1 A g−1), superior rate capability (325 mA h g−1 at 1.0 A g−1) and cycling stability, attributed to their synergistic effect and high Li+ diffusion coefficient DLi [D(NaNbO3/rGO)/D(NaNbO3) ≈ 31.54]. Remarkably, the NaNbO3/rGO-based LIC delivers a high energy density of 166.7 W h kg−1 at 112.4 W kg−1 and remains 24.1 W h kg−1 at an ultrahigh power density of 26621.2 W kg−1, with an outstanding cycling durability (90% retention over 3000 cycles at 1.0 A g−1). This study provides new insights on novel intercalation-type anode material to enrich the materials system of LICs. This work was supported by the Natural Science Foundation of Jiangsu Province (No. BK20170549), the National Natural Science Foundation of China (No. 21706103) and Postdoctoral Science Foundation of Jiangsu Province (No. 2019K295).

The new mineral yurgensonite, ideally K2SnTiO2(AsO4)2, the first natural arsenate with species-defining tin, and the continuous isomorphous series between yurgensonite and katiarsite KTiO(AsO4) are described from sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. Yurgensonite and a Sn-bearing variety of katiarsite are associated closely with one another and with badalovite, pansnerite, yurmarinite, achyrophanite, arsenatrotitanite, hatertite, khrenovite, svabite, sanidine, hematite, cassiterite, rutile and aphthitalite-group sulfates. Yurgensonite occurs as sword-shaped crystals up to 0.01 mm × 0.05 mm × 1 mm or acicular to hair-like individuals up to 1 mm long, typically forming radial aggregates up to 2 mm across. It is transparent, colourless, white or pale beige, with vitreous lustre. The mineral is brittle, cleavage was not observed. Dcalc is 3.877 g cm-3. Yurgensonite is optically biaxial (–), α = 1.764(6), β = 1.780(6), γ = 1.792(6) and 2Vmeas. is large. Chemical composition (wt.%, electron-microprobe; holotype) is: Na2O 0.51, K2O 16.27, Rb2O 0.12, Al2O3 0.26, Fe2O3 4.33, SiO2 0.29, TiO2 10.17, SnO2 22.01, P2O5 0.14, V2O5 0.19, As2O5 40.20, Sb2O5 4.88, SO3 0.28, total 99.65. The empirical formula based on 10 O apfu is (K1.92Na0.09Rb0.01)Σ2.02(Sn0.81Ti0.71Fe3+0.30Sb5+0.17Al0.03)Σ2.02(As1.945Si0.03S0.02P0.01V0.01)Σ2.015O10. Yurgensonite is orthorhombic, Pna21, a = 13.2681(6), b = 6.6209(3), c = 10.8113(5) Å, V = 949.74(7) Å3 and Z = 4. The crystal structure was solved from single-crystal X-ray diffraction data, R = 5.02%. Yurgensonite belongs to the KTP-structure type. It is a Ti,Sn-ordered analogue of katiarsite. The structure contains chains of corner-linked alternating crystallographically non-equivalent octahedra M(1) and M(2). In yurgensonite, Sn4+ prevails in the M(2)O6 octahedron whereas the M(1) site is Ti4+-dominant. The new mineral is named in honour of the Russian mineralogist, geochemist and specialist in studies of ore deposits Professor Georgiy Aleksandrovich Yurgenson (born 1935).

Crystals of Ag0.2K0.8Nb4AsO13 (I) and Ag0.62K0.38Nb4AsO13 (II) were synthesized by a solid-state reaction. Both of them crystallize in the orthorhombic system, space group Cmcm with a = 10.469(2) A, b = 10.403(2) A, c = 10.047(1) A and V = 1094.2(3) A3 for (I) and a = 10.438(5) A, b = 10.443(3) A, c = 10.042(6) A and V = 1094.6(7) A3 for (II). The structural study of the investigated compounds shows that they have a three-dimensional framework. There are tunnels, with hexagonal section, in where Ag+ and K+ cations are located. The characteristics derived from the structural study, which support good ion mobility, have encouraged us to study the ionic conductivity through the complex impedance method. We have studied the effect of the substitution of potassium cations (rK+ = 1.37 A) in the Ag0.2K0.8Nb4AsO13 compound by the silver one (rAg+ = 1.09 A) on the structural and electric properties. For the structural point, we remark that the substitution of potassium by silver causes a slight diminution in the lattice parameters, angles and in distances K/Ag–O. For the electrical point, the substitution of potassium by silver induces the reduction of activation energy.

Crystals of two strontium niobium oxyfluorides, Sr2Nb6O13F8·4H2O and Sr3Nb2O2F12·2H2O, have been grown in phase pure forms via hydrothermal reactions using SrCO3, Nb2O5, and an aqueous HF solution. Single-crystal X-ray diffraction suggests that Sr2Nb6O13F8·4H2O, crystallizing in the orthorhombic centrosymmetric space group, Pbam (No. 55), reveals a new variant of the three-dimensional tungsten bronze structure with three-, four-, and five-membered rings that are composed of corner-sharing NbO2(O/F)2F2, NbO4(O/F)F, NbO3(O/F)3, and SrO3F6 groups. Sr3Nb2O2F12·2H2O with the noncentrosymmetric polar space group, Cmc21 (No. 36), however, reveals a molecular structure consisting of Nb(O/F)2F5 pentagonal bipyramids and two unique Sr2+ cations interacting with F, O/F, and water molecules. Band gaps calculated by the Kubelka-Munk function based on the ultraviolet-visible diffuse-reflectance spectra of Sr2Nb6O13F8·4H2O and Sr3Nb2O2F12·2H2O are estimated to be ca. 3.22 and 4.11 eV, respectively, in which the values are related to the contents of electronegative F atoms and the Nb-O(F)-Nb bond angles influenced by structural distortion. An interesting phase transition reaction from Sr3Nb2O2F12·2H2O to thermodynamically more stable Sr2Nb6O13F8·4H2O occurs under a hydrothermal condition.

Herein, we report the synthesis and characterization of a bishomoleptic and a trisheteroleptic ruthenium (II) polypyridyl complex, namely, [Ru(bpy)2(2, 2′-pq)](PF6)2 (1) and [Ru(bpy) (phen) (2, 2′-pq)](PF6)2 (2), respectively, where bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, and 2, 2′-pq = 2-(2′-pyridyl)-quinoxaline. The complexes were characterized by elemental analysis, TGA, 1H-NMR, FT-IR, UV-Vis, emission spectroscopy, and electrochemistry. Their structures were confirmed by single-crystal X-ray diffraction analysis. Complexes 1 and 2 were crystalized in orthorhombic, Pbca, and monoclinic, P21/n systems, respectively. Various spectroscopic techniques were employed to investigate the interaction of both complexes with calf thymus DNA (CT-DNA). The experimental data were confirmed by molecular docking studies, employing two different DNA sequences. Both complexes, 1 and 2, bind with DNA via a minor groove mode of binding. MTT experiments revealed that both complexes induce apoptosis of MCF-7 (breast cancer) cells in low concentrations. Confocal microscopy indicated that 2 localizes in the nucleus and internalizes more efficiently in MCF-7 than in HEK-293.

Molybdenum trioxide (MoO3) micro-belts were successfully synthesized via the sol–gel coprecipitation method. The synthesized material was, then, doped with different concentrations of yttrium element, Y. The influence of the doping concertation on crystallographic, microstructural, optical, and photocatalytic properties has been studied. Good thermal stability has been revealed by thermogravimetric analysis. The X-ray diffraction analysis identified the orthorhombic phase. The peaks were shifted toward the lower 2θ angle position after doping, confirming the Y3+ substitution in the MoO3 crystal structure. Scanning electron microscope measurements revealed a belt-like shape with a decreasing size when increasing the Y3+ ions concentration. SEM clearly showed a non-homogeneous distribution of second-phase particles, depending on the concentration of yttrium doping, which could be attributed to the Y2Mo4O15 secondary phase. The band-gap energy was shifted to the lower-energies of an amount of 0.61 eV when going from 0 to 10% of yttrium. The photocatalytic performances were monitored through photodegradation of methylene blue under different radiations. It was observed that Y-dopant significantly improved the photocatalytic activity of MoO3, the longer the wavelength the better the removal efficiency. This enhancement could be associated with the doping-induced modification of the band-gap or to the microstructure evolution.

Complex oxides Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0–0.4) have been prepared by a pyrolysis of glycerol-nitrate compositions. According to the X-ray diffraction analysis, the materials are single-phase up to y = 0.3 and crystallize in an orthorhombic structure (Bmab) at room temperature. High-temperature studies assert that they all undergo a phase transition from orthorhombic to tetragonal (I4/mmm) structure in a range of 300–400 °C. With Cu doping, the over-stoichiometric oxygen content δ decreases from 0.07 (y = 0.0) down to 0.00 (y = 0.3). The studies on the compact samples reveal the maximum value of total conductivity (165 S cm−1 at 420 °C) and the minimum value of the linear coefficient of thermal expansion (11.9·10−6 K−1 in a range of 400–1000 °C in air) at y = 0.2. Chemical compatibility of the Nd1.6Cа0.4Ni1-yCuyO4+δ (y = 0.0, 0.2) oxides with oxygen- and proton conducting electrolytes (Ce0.9Gd0.1O1.95, Ce0.8Sm0.2O1.9 and BaCe0.5Zr0.3Y0.1Yb0.1O3-δ) up to a temperature of 1100 °C is demonstrated.

Perovskite-like complex oxide La0.5Ca0.5Mn0.5Co0.5O3±δ synthesized by the Pechini method is characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Structural transformations of this compound in the media with different partial pressures of oxygen and in the medium with hydrogen are studied in situ for the first time. The solid solution in the medium with low partial pressure of oxygen is shown to be unstable. The structural state of the sample is affected not only by the presence/absence of oxygen in the medium but also by the rate of sample cooling. X-ray diffraction and thermal analysis reveal that perovskite undergoes polymorphic transition from orthorhombic to cubic symmetry at 600 °C due to oxygen loss. Reducing the sample by hydrogen leads to the formation of two perovskite-like phases with pseudo-cubic and orthorhombic symmetries, possibly, due to the inhomogeneous formation of vacancies in the solid solution and changes in the oxidation states of cobalt and manganese cations. It is shown that the initial structure can be partially regenerated from the complex oxide reduced in H2.

Compositions of V2−xTixO5−δ (x = 0.15, 0.20, 0.25, and 0.30) are synthesized by the melt-quench technique. Different experimental techniques are used to study structural, optical, thermal, and electrical properties. Various physical parameters are also calculated using apparent density to support the conduction mechanism of the prepared samples. X-ray diffraction (XRD) is confirmed the formation of orthorhombic V2O5 phase. The doping of TiO2 supports the transfer of VO5 structural units into VO4 units as confirmed by Fourier transform infrared (FTIR) and Raman spectroscopy. The optical band gap (Eg) and Urbach energy (EU) of the TiO2-doped vanadium samples are obtained with the help of diffused reflectance spectra (DRS). A marginally decreasing trend in the optical band gap (2.28–2.20 eV) is observed with dopant content. X-ray photoelectron spectroscopy measurement is confirmed that vanadium is present in mixed state, i.e., V5+ and V4+ which leads to the increase in conductivity of the doped samples. The highest DC conductivity is observed about 1.12 S m−1 at 400 °C.

Orthorhombic β-LiVOPO4/ketjen black composite is obtained via a two-step chemical synthesis. In the first step, Li3V2(PO4)3-V2O3/ketjen black precursor is obtained by spray-drying process and subsequent heat treatment. Solvent-thermal oxidation of the precursor results in the complete formation of β-LiVOPO4/ketjen black composite. The synthesized composite is characterized by means of X-ray diffraction, scanning electron microscopy, nitrogen sorption, and electrochemical tests. Galvanostatic charge–discharge cycling of the composite shows an initial discharge specific capacity of 305, 289, 276, 242, 157, and 77 mAh·g−1 at C/20, C/10, C/5, C/2, 1C, and 2C rate in a voltage window of 2.0–4.5 V, respectively. At higher current rates, although it exhibits good retention of discharge capacity, the capacity is found to reduce with increasing current rates. The composite displays excellent cycling performance at a current rate of C/5 up to 50 cycles, which yields a high specific capacity of 245 mAh·g−1 at the end of the 50th cycle and a small capacity fading of 0.13% per cycle.