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This investigation involves the synthesis and study of dielectric, structural and impedance properties of polycrystalline Bi(Ni 2/5 Ti 2/5 Fe 1/5)O 3 (symbolized as BNTF) nano-ceramic. The BNTF polycrystalline sample was fabricated through the use of a conventional solid-state reaction route. X-ray structural examination reveals that the parent compound (i.e., BiFeO 3) crystallizes in the rhombohedral structure (space group-R3c) while that the BNTF compound crystallizes in orthorhombic symmetry. The substitution of NiTiO 3 into BiFeO 3 enhances various properties and reduces electrical leakage current. The average crystallite size is calculated to be 29 nm. The room temperature textures and surface morphologies of the specimen were verified by field-emission scanning electron microscope, and show uniform grains distribution on sample surfaces. Dielectric parameters (constant and tangent-loss) and impedance spectroscopy parameters of NiTiO 3 modified BiFeO 3 compound were investigated over a wide temperature range (25–500 °C) at different frequency (25 kHz-500 kHz), which offers several interesting features of BNTF material suitable for further device applications. [ABSTRACT FROM AUTHOR]

A copper‐catalyzed 8‐aminoquinoline‐directed oxidative cross‐coupling of the C−H bond of ferrocene with sodium arylsulfinates has been achieved. The robust copper catalyst tolerates a range of methyl, tert‐butyl, bromo, chloro, iodo and nitro functional groups in the phenyl ring, and set the stage for the synthesis of substituted ferrocene sulfones. Furthermore, X‐ray crystal structure study on several ferrocenyl sulfones reveals the tetrahedral geometry around sulfur; interestingly, the O‐S‐O angle is larger than the electropositive substituent C‐S‐C angle which could be explained by Bent's rule. Further, unusual intramolecular O(S)⋅⋅⋅N(amide) short contacts (2.925–3) and O(S)⋅⋅⋅C=O were also noticed in ferrocenyl sulfones. [ABSTRACT FROM AUTHOR]

Abstract In this communication, studies of basic crystal structure, microstructure, dielectrics, impedance, conductivity, electric polarization and magnetization of an eco-friendly distorted perovskite Bi(Co 0.35 Ti 0.35 Fe 0.30)O 3 (abbreviate as BCTF70/30) have been reported. Analysis of crystal structure, phase formation and composition of the specimen, carried out through the powder X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDXS) techniques, confirms the formation of single-phase orthorhombic system at room temperature. The surface morphology of the compound, evaluated through the field emission scanning electron microscope, displayed the formation of high-density sample with uniform distributions of grains of varying dimensions. The phonon mode, intensity, location and width of the Raman peaks were analyzed using the Raman spectroscopy. The correlation between the frequency-temperature dielectric parameters, impedance parameters and electrical conductivity with structure-microstructure has been established. The influence of grain and grain boundary on the resistive and capacitive features has been examined through impedance spectroscopy formalism with an idealized simulated circuit. Studies of impedance spectroscopic show the semiconductor nature (i.e., negative temperature coefficient of resistance) and the non-Debye type relaxation. Polarization versus electric field analysis of BCTF70/30 sample displays enhanced value of remnant polarization as compared to that of BFO. The magnetic hysteresis loop analysis also exhibits significant improvement in the magnetization values of the compound. Accordingly, based on such enhancement of remnant polarization and magnetic parameters, we assumed that an eco-friendly material of BCTF70/30 could considered as promising material for some new electronic devices. [ABSTRACT FROM AUTHOR]

Dielectric studies were carried out on Nd 2 CuTiO 6 samples prepared by high temperature solid-state reaction followed by annealing under different oxygen partial pressures. X-ray diffraction studies revealed that the orthorhombic (Pnma) structure of Nd 2 CuTiO 6 is retained in all the samples. The room temperature permittivity at 100Hz was found to be about 200 in the air-annealed sample, and it increased considerably to about 3000 upon annealing in argon atmosphere. The electrical conductivity in the argon-annealed compound was found to be an order of magnitude higher than that for the air-annealed sample. On annealing in oxygen, both permittivity and electrical conductivity of the sample were found to be significantly reduced. The variation in dielectric properties could be attributed to the induction or annihilation of mixed valence state of copper and oxygen vacancies, which was supported by X-ray photoelectron and diffuse reflectance spectroscopy data. The analysis of temperature and frequency dependent conductivity and dielectric data showed that the overlapping large polaron tunnelling (OLPT) mechanism is responsible for the observed dielectric relaxations and conduction. The observed systematic dependence of properties on the oxygen partial pressure of the annealing environment suggests a simple method to tune the electrical properties of Nd 2 CuTiO 6. • Annealing conditions affect dielectric properties in rare-earth double perovskite. • Crystalline structure remains unchanged. • Changes in mixed valence of copper and oxygen vacancies. • Dielectric properties may be tuned by varying synthesis conditions. • Conduction due to overlapping large polaron tunnelling. [ABSTRACT FROM AUTHOR]

First principles calculations are used to study the initial decomposition reactions of ethylene carbonate (EC) on the (111) surface of LiMm2O4 (LMO), a candidate for Li ion battery (LIB) cathode. Theoretical studies of interfacial reactions are particularly timely due to recent experiments on the effect of LMO crystal morphology on battery cyclability and interfacial film stability [J.-S. Kim, K. Kim, W. Cho, W. H. Shin, R. Kanno, and J. W. Choi, Nano Lett., 12, 6358-6365 (2012)]. We find that EC degradation is a two-step reaction. The first step is the rate determining reaction where a proton is abstracted from EC and transferred to the surface. The second step involves ring opening of the proton abstracted EC which turns out to have a smaller barrier. Both of these reactions are sensitive to the Li content, i.e. state of charge, of the model electrode. EC degradation via H-abstraction becomes a feasible reaction route when the cathode becomes more highly charged. Comparison with predictions on the (100) surface of LMO is discussed, and speculation on the growth of nanometer-thick interfacial layer on LMO despite its relatively modest operating potential are made in light of the reaction driving forces predicted in this work. [ABSTRACT FROM AUTHOR]

Neisseria gonorrhoeae is an obligate human pathogen and the causative agent of the sexually-transmitted disease gonorrhea. The control of this disease has been compromised by the increasing proportion of infections due to antibiotic-resistant strains, which are growing at an alarming rate. The MtrCDE tripartite multidrug efflux pump, belonging to the hydrophobic and amphiphilic efflux resistance-nodulation-cell division (HAE-RND) family, spans both the inner and outer membranes of N. gonorrhoeae and confers resistance to a variety of antibiotics and toxic compounds. We here report the crystal structure of the inner membrane MtrD multidrug efflux pump, which reveals a novel structural feature that is not found in other RND efflux pumps. [ABSTRACT FROM AUTHOR]

Active efflux of antimicrobial agents is one of the most important strategies used by bacteria to defend against antimicrobial factors present in their environment. Mediating many cases of antibiotic resistance are transmembrane efflux pumps, composed of one or more proteins. The Neisseria gonorrhoeae MtrCDE tripartite multidrug efflux pump, belonging to the hydrophobic and amphiphilic efflux resistance-nodulation-cell division (HAE-RND) family, spans both the inner and outer membranes of N. gonorrhoeae and confers resistance to a variety of antibiotics and toxic compounds. We here describe the crystal structure of N. gonorrhoeae MtrE, the outer membrane component of the MtrCDE tripartite multidrug efflux system. This trimeric MtrE channel forms a vertical tunnel extending down contiguously from the outer membrane surface to the periplasmic end, indicating that our structure of MtrE depicts an open conformational state of this channel. [ABSTRACT FROM AUTHOR]

A newReaxFF reactive force field has been developed to describereactions in the Ti–O–H system. The ReaxFF force fieldparameters have been fitted to a quantum mechanical (QM) trainingset containing structures and energies related to bond dissociationenergies, angle and dihedral distortions, and reactions between waterand titanium dioxide, as well as experimental crystal structures,heats of formation, and bulk modulus data. Model configurations forthe training set were based on DFT calculations on molecular clustersand periodic systems (both bulk crystals and surfaces). ReaxFF reproducesaccurately the QM training set for structures and energetics of smallclusters. ReaxFF also describes the relative energetics for rutile,brookite, and anatase. The results of ReaxFF match reasonably wellwith those of QM for water binding energies, surface energies, andH2O dissociation energy barriers. To validate this ReaxFFdescription, we have compared its performance against DFT/MD simulationsfor 1 and 3 monolayers of water interacting with a rutile (110) surface.We found agreement within a 10% error between the DFT/MD and ReaxFFwater dissociation levels for both coverages. [ABSTRACT FROM AUTHOR]

Low electric and magnetic moment features are the main drawbacks that restrict the practical utilities of bismuth ferrite. Successfully, we have substituted Li+ and W6+ in Sb3+ and Fe3+ sites to eliminate further confinements of bismuth ferrite (referred as BFO/BiFeO 3). A new lead-free perovskite compound of (SbLi) 1/2 (Fe 2/3 W 1/3)O 3 (symbolized as SLFWO) has been produced through ceramic processing (high temperature) route. The calcination temperature of said compound is confirmed from the thermogravimetric analysis. The structural, microstructural, magnetic and electrical (dielectric constant/loss, impedance, modulus, conductivity) features of the said material have been studied over an extensive range of frequency (100 Hz-1 MHz) and temperature (RT-400 °C). The finding of reflection indices and crystal parameters approve the development of polycrystalline nature with orthorhombic symmetry of the compound. The impedance analysis confirms the existence of non-Debye type relaxation trend. The frequency-temperature dependence of ac-conductivity studies proves the nature and conduction mechanism in the compound. At specific peak frequency, the modulus spectrum movements of the charge carrier vary from wide array to narrow array. The peak frequencies increase with temperature signifying the thermally activated relaxation process. The value of leakage current rises with the temperature that established the NTCR trend of the compound. The observed values of remanent magnetization, saturation magnetization and coercivity of SLFWO are 0.5647 emu/g, 0.04953 emu/g, and 104.242 Oe respectively. • The material is quite new considering its application point of view. • The structural, thermal, impedance and magnetic properties with in-depth understanding are explained well in this manuscript. • The material has an excellent electrical and magnetic property. [ABSTRACT FROM AUTHOR]