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In this paper, Fe-N 3 S 1 and FeS sub-nano cluster are innovatively connected to S, N co-doped carbon matrix (SNC) by controlled calcination process. The local electron configuration of Fe center is modulated by this unique structure. Based on this design, Fe-N 3 S 1 and FeS sub-nano cluster shown excellent synergistic effects in oxygen reduction reaction. The optimized ORR activity was obtained. [Display omitted] Single atomic Fe-N 4 catalyst exhibits a great prospect for oxygen reduction reaction (ORR) and adjusting the intrinsic coordination structure and the carbon matrix structure effectively improves the catalytic activity. However, controlling the active site coordination structure and its surrounding environment at atomic level remains a challenge. In this paper, Fe-N 3 S 1 and FeS sub-nano cluster were innovatively concatenated on S, N co-doped carbon matrix (SNC), denoted as FeS/FeSA@SNC catalysts, for modulating ORR catalysis performance. Both experimental measurements and theoretical calculations have confirmed that the local electron configuration of Fe center is modulated by this unique structure combination leading to optimized ORR kinetics. Based on this design, the synthesized FeS/FeSA@SNC delivers ORR activity with a half-wave potential of 0.9 V (vs. RHE), excelling that of commercial Pt/C (0.87 V) and the Zn-air battery (ZAB) with this cathode catalyst delivers a peak power density of 126 mW cm−2. This work presents a novel strategy for manipulating the single-atom active sites through control the local coordination structure and provides a reference for the development of novel efficient ORR electrocatalysts. [ABSTRACT FROM AUTHOR]

This work vividly demonstrates the rational design of VSe 2-x O x -SS cathode as an effective strategy to achieve fast and highly aqueous zinc ion storage. [Display omitted] • A simple and fast surface oxygen implantation strategy was designed to adjust the electronic structure of VSe 2 and form a surface protective film. • The VSe 2-x O x -SS-30 electrode showed higher specific capacity, better rate performance and more satisfactory cycling stability. • The zinc (de)intercalation and transformation reactions mechanism was revealed by some ex-situ/in-situ techniques. Interfacial chemical modification is an effective strategy to adjust the strong Coulombic ion-lattice interactions with high valence cations experienced by electrode materials, facilitating the reaction kinetic. In this paper, a simple and fast surface oxygen implantation strategy was designed to adjust the electronic structure of stainless steel (SS) supported vanadium diselenide (VSe 2) nanosheets and form a surface protective film, which effectively accelerates the reaction kinetics of Zn2+ and extends the cycle life of the battery. It is demonstrated that the conductivity, pseudocapacitance and specific capacity can be tuned by selectively introducing oxygen species to the surface, which provides an important reference for the design of electrodes with controlled surface chemistry. Density functional theory (DFT) calculations also confirm that the electronic structure can be adjusted by surface oxygen injection strategy, which not only improves the conductivity, but also adjusts the adsorption energy, thus providing favorable conditions for zinc ion storage. Benefiting from the selenium vacancies and pores generated by the removal of part of selenium, and the oxide film formed on the surfaces, the VSe 2-x O x -SS-30 electrode showed higher specific capacity (188.4 mAh/g at 0.5 A g−1 after 50 cycles), better rate performance (107.1 mAh/g at 4 A g−1) and more satisfactory cycling stability (83.1 mAh/g at 5 A g−1 after 1800 cycles) than VSe 2 -SS electrode. Importantly, the flexible quasi-solid-state VSe 2-x O x -SS-30//Zn battery also exhibits high specific capacity and excellent environmental adaptability. Furthermore, the zinc (de)intercalation and transformation reactions mechanism was revealed by some ex-situ/in-situ techniques. [ABSTRACT FROM AUTHOR]

Facile synthesis of FeNi alloy-supported N -doped Mo 2 C hollow nanospheres for enhanced oxygen evolution reaction. [Display omitted] • Facile synthesis of FeNi alloy-supported N -doped Mo 2 C hollow nanospheres. • FeNi/Mo 2 C/NC supports strongly accelerated electron transfer, thereby improving the OER kinetics. • FeNi/Mo 2 C/NC hybrids will hold promise in development of electrode materials. The rapid depletion of fossil fuels results in significant environmental pollution. Consequently, researching environmentally friendly and cost-effective electrocatalysts with exceptional oxygen evolution reaction (OER) capabilities holds immense importance in enhancing the efficient utilization of resources. In this paper, a straightforward and cost-effective method was employed to produce Fe-Ni alloy-supported N -doped carbon hollow nanospheres (FeNi/Mo 2 C/NC) using self-assembled molybdenum dopamine spheres (Mo-PDA-HS) as a substrate. The inclusion of iron and nickel addressed the issue of aggregation and collapse in Mo-PDA-HS nanostructures at high temperatures, while adjusting the electronic structure of the composites to achieve efficient OER activity. The composite displayed a low overpotential (η10 mA = 304 mV) and a minimal Tafel slope (41.8 mV/dec-1). This study introduces a simple strategy for constructing structurally robust and non-aggregating Mo 2 C nanostructures, along with a direct method for designing cost-effective and high-performance catalysts for OER. [ABSTRACT FROM AUTHOR]

[Display omitted] Solar energy conversion into hydrogen (H 2) energy has attracted much attention. However, the low light utilization rate and fast carrier recombination of photocatalysts extremely limit the practical application of photocatalytic H 2 production. In this paper, MoSe 2 -NiSe with abundant active sites and interfacial electronic structures as dual co-catalysts were assembled on g-C 3 N 4 nanosheets (NSs) vis a solvothermal reaction process. MoSe 2 -NiSe/g-C 3 N 4 NSs composite exhibited improved light absorption and photoelectrochemical properties. The photocatalytic H 2 production rate of MoSe 2 -NiSe/g-C 3 N 4 composite achieved 2379.04 μmol·h−1·g−1, which is 99.25, 1.44, and 3.67 times those of pure g-C 3 N 4 nanosheets (23.97 μmol·h−1·g−1), MoSe 2 /C 3 N 4 (1654.57 μmol·h−1·g−1), and NiSe/C 3 N 4 (649.08 μmol·h−1·g−1), respectively. The apparent quantum efficiency (AQE) value of MoSe 2 -NiSe/g-C 3 N 4 achieved 4.07 % under light at λ = 370 nm. The corresponding characterization and experiments proved that 2D ultrathin g-C 3 N 4 NSs with a large surface area and short charge-transfer distance could facilitate light scattering and the transport of photoexcited electrons. MoSe 2 -NiSe, as a dual co-catalyst, showed strong electronic synergistic interaction between the interfaces, thus improving the conductivity and promoting the electron transfer process. [ABSTRACT FROM AUTHOR]

[Display omitted] • The porous few-layer bimetallic co-doped g-C 3 N 4 is prepared via a facile bottom-up method. • The bimetallic synergetic regulating effect on the electronic structure can be produced in Co/Ni-g-C 3 N 4. • The superior performance results from the improved charge separation efficiency and visible light harvestability. • This work provides meritorious guidance for new bimetallic co-doped g-C 3 N 4 photocatalysts. The low specific surface area and low charge transfer efficiency of conventional graphite carbon nitride (g-C 3 N 4) are the main obstacles to its application in photocatalytic CO 2 reduction. In this paper, graphite carbon nitride was protonated by phosphoric acid (H 3 PO 4), and a new few-layer porous carbon nitride was prepared by intercalation polymerization with doping bimetal in the cavity of g-C 3 N 4. Under visible light irradiation, the CO formation rate of Co/Ni co-doped g-C 3 N 4 can reach 13.55 μmol g−1 h−1, which was 3.9 times higher than that of g-C 3 N 4 (3.49 μmol g−1 h−1). The density functional theory (DFT) calculations showed that the addition of Co and Ni in the cavity of g-C 3 N 4 can induce bimetallic synergistic regulation of the electronic structure, thus improving the separation efficiency of charges and visible light capture ability of g-C 3 N 4. Our work has great reference value for designing and synthesizing novel bimetallic co-doped g-C 3 N 4 photocatalytic materials. [ABSTRACT FROM AUTHOR]

[Display omitted] As a promising dopant, electron deficient B atom not only tunes the electronic structure of electrocatalysts for improving their intrinsic catalytic activities, but also combines with hydroxy radical as strong adsorption sites for accelerating the water dissociation during the hydrogen evolution reaction (HER). In this paper, we report an electrocatalyst based on boron-modified Ru anchored on carbon nanotubes (B-Ru@CNT) that shows impressive HER activity in acidic and alkaline media. The boron-rich closo -[B 12 H 12 ]2- borane was selected as a moderately strong reductant for the in situ reduction of a Ru salt, which yielded B-doped Ru nanoparticles. The experimental and theoretical results indicate that the incorporation of B not only weakens the Ru-H bond and downshifts the d-bond centre of Ru from the Fermi level by reducing the electron density at Ru but also accelerates the water dissociation reaction by providing B sites, which strongly adsorb OH* intermediates, and nearby Ru sites, which act as sites for the adsorption of the H* intermediate, thus boosting the HER performance and enhancing the HER kinetics. As a result of the tuning of the electronic structure via B doping, B-Ru@CNT showed excellent HER performance, yielding overpotentials of 17 and 62 mV at a current density of 10 mA cm−2 in alkaline and acidic solutions, respectively. These results indicate that our synthetic method is a promising route to B-doped metallic Ru with enhanced pH-independent HER performance. [ABSTRACT FROM AUTHOR]

[Display omitted] Defect engineering is an important strategy to regulate electronic structure of electrocatalysts for electrochemical N 2 fixation, aiming at improving the electron state density and enhancing the adsorption and activation of inert N 2. In this paper, a high-temperature strategy to anneal the natural molybdenite under Ar atmosphere was developed, and the as-obtained molybdenite with S vacancies boosted a high activity for N 2 reduction reaction. In 0.1 M HCl, the catalyst annealed at 800 °C exhibits a high Faradic efficiency of 17.9% and a NH 3 yield of 23.38 μg h−1 mg-1 cat. at −0.35 V versus reversible hydrogen electrode, two times higher than that of the pristine molybdenite. The facile one-step annealing method introduces the defects (e.g., S vacancies) in the surface of the natural molybdenite particles to prepare catalysts for generating ammonia by reducing nitrogen at room temperature under ordinary pressure, promoting the development of low-carbon economic prospect. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) graphitic carbon nitride (g-C 3 N 4) nanoplates (CNNP) have become a hot research topic in photocatalysis due to their small thickness and large specific surface area that favors charge transport and catalytic surface reactions. However, the wide application of 2D g-C 3 N 4 nanoplates prepared by ordinary methods suffers from increased band gaps with a poor solar harvesting capability caused by the strong quantum confinement effect and reduced conjugation distance. In this paper, a facile approach of exfoliation and the following fast thermal treatment of the bulk g-C 3 N 4 is proposed to obtain a porous few-layered g-C 3 N 4 with nitrogen defects. Due to the preferable crystal, textural, optical and electronic structures, the as-obtained porous CNNP demonstrated a significantly improved photocatalytic activity towards water splitting than the bulk g-C 3 N 4 and even the 3 nm-thick CNNP obtained by sugar-assisted exfoliation of the bulk g-C 3 N 4. The difference in the enhancement factors between the H 2 O splitting and organic decomposition has revealed the effect of N defects. This study offers insightful outlooks on the scalable fabrication of a porous few-layered structure with a promoted photocatalytic performance. [ABSTRACT FROM AUTHOR]

Abstract For the first time, a mixed-alkali diphosphate, Li 2 Na 2 P 2 O 7 , has been successfully obtained by high-temperature solution growth (HTSG) method. Single crystal X-ray diffraction analysis reveals that it contains anionic [Li 2 P 2 O 7 ] ∞ network and 1D [Na] ∞ infinite chains, which are both running along the c -axis. Band structure calculations by density functional theory (DFT) method indicate that Li 2 Na 2 P 2 O 7 has an indirect band gap of about 4.88 eV. Moreover, 1 mol% Eu3+ doped Li 2 Na 2 P 2 O 7 phosphor was synthesized and its photoluminescence properties were investigated. Under near ultraviolet (NUV) excitation (394 nm), Li 2 Na 2 P 2 O 7 :0.01Eu3+ phosphor exhibits a series of emission peaks corresponding to the 5D 0 →7F J (J = 0, 1, 2, 3, 4) transitions of Eu3+ ion with the CIE chromaticity coordinates of (0.599, 0.375). Graphical abstract This paper affords a novel lithium sodium diphosphate Li 2 Na 2 P 2 O 7 via high temperature flux method. The wide band gap of about 4.88 eV makes it suitable to be used as a luminescent host matrix. It can emit intense red light after doping with Eu3+ ions. fx1 Highlights • This work provides a novel lithium sodium diphosphate, Li 2 Na 2 P 2 O 7. • Li 2 Na 2 P 2 O 7 has an indirect bond gap of about 4.88 eV. • 1 mol% Eu3+ activated phosphor was synthesized by a solid-state reaction and its photoluminescence properties were studied. • Under 394 nm light excitation, Li 2 Na 2 P 2 O 7 :0.01Eu3+ exhibits a series of bonds corresponding to the 5D 0 →7F J (J = 0, 1, 2, 3, 4) of Eu3+ ion. [ABSTRACT FROM AUTHOR]

In this paper, the carbon-doped boron nitride nanoplate (C-BNNP) was prepared by pyrolyzing the precursor under N 2 and served as an excellent adsorbent for removal of Rhodamine B (RhB). The structure and composition of C-BNNP were characterized and its adsorption behavior for RhB was investigated. Compared with boron nitride nanoplate (BNNP) which was synthesized under NH 3 , C-BNNP displayed an enhancement of the adsorption capacity for RhB (833 mg/g). The adsorption activity was comprehensibly studied by kinetics, isotherm and thermodynamics. The adsorption kinetics followed pseudo-second-order model. The equilibrium adsorption data agreed well with the Langmuir isotherm. And the thermodynamics indicated that the adsorption process was a spontaneous, exothermic and physisorption process. In addition, the density functional theory was proposed that doping carbon in the BNNP decreased the chemical hardness of the adsorbent and enhanced the adsorption capacity of C-BNNP for RhB. [ABSTRACT FROM AUTHOR]

Defect-related photoluminescence (PL) in materials have attracted interest for applications including near ultraviolet (NUV) excitable light-emitting diodes and in biomedical field. In this paper, hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ] nanorods with intense PL bands (bluish- and yellowish-white emissions) were obtained when excited under NUV radiation at room temperature. These nanoparticles were synthesized via chemical precipitation at 90 °C followed by distinct heat treatments temperatures (200–800 °C). Intense and broad emission profiles were achieved at 350 °C (380–750 nm) and 400 °C (380–800 nm). UV–Vis spectroscopy revealed band gap energies (5.58–5.78 eV) higher than the excitation energies (~3.54 and ~2.98 eV at 350 and 415 nm, respectively), confirming the contribution of defect energy levels within the forbidden zone for PL emissions. The structural features were characterized by X-ray diffraction, Rietveld refinement, thermogravimetric analysis, and Fourier transform infrared spectroscopy. By means of these techniques, the relation between structural order-disorder induced by defects, chemical reactions at both lattice and surface of the materials as well as the PL, without activator centers, was discussed in details. [ABSTRACT FROM AUTHOR]

It is an important topic to investigate the birefringence and reveal the contribution from ions to birefringence because it plays an important role in nonlinear optical materials. In this paper, the birefringence of carbonates with coplanar CO 3 groups were investigated using the first-principles method. The results show that the lead carbonates exhibit relative large birefringence. After detailed investigate the electronic structures, and Born effective charges, the authors find out that anisotropic electron distribution in the CO 3 groups and Pb atoms give positive contribution, while the negative contribution was found from fluorine atoms, meanwhile the Ca, Mg, and Cd atoms give very small contribution to birefringence. [ABSTRACT FROM AUTHOR]

The purpose of the paper is to establish the position of the tie-lines in the Sb-Sm-Se system at 450 ​°C and 620 ​°C, to determine the optical band gap of the phases. The Sb component is in equilibrium with the γ-Sm 2 Se 3-X -Sm 3 Se 4 (ST Th 3 P 4) solid solution region with α-Sm 2 Se 3. A continuous solid solution forms between the SmSb and SmSe (ST NaCl) phases, with which the Sm 3 Se 4 and Sm 4 Sb 3 phases are in equilibrium. The SmSb-Sm 3 Se 4 , Sm 3 Se 4 -SmSb 2 , SmSe-Sm 3 Sb 2 phases are also in equilibrium. In the Sb–Sm 2 Se 3 –Se system at 450°С, the tie-line passes between the Sb 2 Se 3 –Sm 2 Se 3 , Sb 2 Se 3 -SmSe 1.9 phases. In the Sb–Se system based on Sb 2 Se 3 , a solid solution of the subtraction type Sb 2-X □ X Se 3 (X ​= ​0–0.04) is formed. In the Sb-Sm-Se system, there is a solid solution of the substitution type along the cuts from Sb 2 Se 3 to the Sm 2 Se 3 (7 ​mol. % Sm 2 Se 3), SmSe 1.9 (4 ​mol. % SmSe 1.9) phases. The extreme compositions of solid solutions have a peritectic point. Due to the change in the position of the tie-lines in the Sb–Sm 2 Se 3 –Se system at 620 ​°C, additional phases appear in the equilibrium samples from the Sb 2 Se 3 –Sm 2 Se 3 section (annealing at 450 ​°C) when heated above 620 ​°C: Sb, SmSe 1.9. The optical band gap of the phases is: Sb 2-x Sm x Se 3 solid solution 1.17–1.19 ​eV, α-Sm 2 Se 3 1.62 ​eV. Optical properties of incommensurate SmSe 1.9 crystal that were investigated for the first time for this class of crystals indicate complex electronic structure that can be characterized as a multi band gap one, with at least two values of the band gap, 1.08 and 1.68 ​eV. Using optical spectroscopy, Sm ions in SmSe 1.9 are proved to be predominantly in 3+ oxidation state. Previously, the formation of ternary compounds in the system was reported in the literature. Carefully conducted research allows us to assert their absence. [Display omitted] • The conditions for obtaining equilibrium samples in the Sb-Sm-Se system were established. • Sb is in equilibrium with the γ-Sm 2 Se 3-X -Sm 3 Se 4 solid solution. • In the Sb-Sm-Se system at 450 and 620 ​°C, 18 tie-lines and 15 subsystems were identified. • In the Sb–Se system based on Sb 2 Se 3 , a solid solution of the subtraction type Sb 2-X X Se 3 (x ​= ​0–0.04) is formed. • The optical band gap of the phases is: Sb 2-x Sm x Se 3 solid solution 1.17–1.19 ​eV, α-Sm 2 Se 3 1.62 ​eV, SmSe 1.9 1.68 ​eV. [ABSTRACT FROM AUTHOR]

In this paper, we report the effect of the tunnel anions on the ionic conductivity of Strontium-Lanthanum silicate apatites. The Sr 4 La 6 (SiO 4 ) 6 F 2 and Sr 4 La 6 (SiO 4 ) 6 O ceramics were prepared by the solid state reaction method. X-ray diffraction, NMR spectroscopy and Raman measurements were performed to investigate the crystal structure and vibrational active modes. Moreover, the electronic structures of the crystals were evaluated by the first-principles quantum mechanical calculation based on the density functional theory. Finally, the ionic conductivity was studied according to the complex impedance method. [ABSTRACT FROM AUTHOR]

The structural, elastic, electronic and optical properties of K 2 CuBiX 6 (X ​= ​Br, Cl) are studied by the first principle calculation in this paper. Their structural and thermodynamic stabilities are guaranteed by the formation energy, binding energy and Born-Huang criterion. The results of elastic constants show that the two materials are ductile and can be applied in foldable optoelectronic devices. Besides, The calculated bandgap values are 1.03 ​eV and 1.44 ​eV for K 2 CuBiBr 6 and K 2 CuBiCl 6 , respectively, which is just in the ideal energy gap range of semiconductors. K 2 CuBiX 6 has very small effective mass advantageous to carrier transport. In addition, the optical properties analysis shows that K 2 CuBiX 6 has excellent light absorption properties in ultraviolet–visible wavelength. Due to their suitable bandgaps and good light absorption, K 2 CuBiX 6 has a promising application in solar cells and other optoelectronic devices. In this study, the perovskites K 2 CuBiX 6 (X ​= ​Br, Cl) are proposed as functional materials in solar cells. [Display omitted] • The K 2 CuBiX 6 (X ​= ​Br, Cl) are very suitable for photosensitive materials of solar cells. • The K 2 CuBiX 6 can be a potential candidate for excellent light absorbing material. • The K 2 CuBiX 6 is the structural and thermodynamic stabilities. [ABSTRACT FROM AUTHOR]

Abstract: The electronic and lattice dynamic properties of I 2–II–IV–VI 4 quaternary diamond-like semiconductors have a tight connection with their application in the area of solar cell absorption, thermoelectric conversion and so on. Structural configuration of these compounds is focused in present study, although previous researches always pay close attention to compositional modulation. In this paper, Ag2CdGeS4 polytypes (two types of Pna21, one type of Pmn21) have chosen as the representation to establish the relationship between cation ordering and physiochemical properties based on first-principle theory. The results show that cation arrangement practically affects their electronic and lattice dynamic properties such as bonding strength, band structure as well as their infrared spectrum. Due to different cation arrangement, two types (named model S and model P) of the same space group Pna21 demonstrate different properties. For both model P and Pmn21 of different space group, their related properties are alike because of similar cation arrangement. With the resulting cationic Born effective charges, the origin of the difference in electronic properties for three types of Ag2CdGeS4 can be reasonably explained from the viewpoint of vibrational polarization. [Copyright &y& Elsevier]

Abstract: This paper presents a study of the synthesis and structural properties of the new pyrochlore-type Bi2−y Sr y Ir2O7 series. Ten compositions with 0.0≤y≤0.9 were prepared by solid-state reaction with thermal treatments at 873, 1073 and 1323K under atmospheric pressure conditions. Structural refinements from X-ray powder diffraction data by the Rietveld method show that all compounds of the Bi2−y Sr y Ir2O7 solid solution crystallize in a α-pyrochlore structure. The main structural difference when bismuth is substituted by strontium concerns the x position of the O1 (x, ⅛, ⅛). This substitution significantly increases the Bi/Sr–O1 distance and diminishes the Ir–O1 distance; this implies that the Ir–O1–Ir bond angle increases. With the Sr substitution, the IrO6 local configuration goes from a flattened trigonal antiprism, y<0.5, to an elongated one, y>0.5, passing through an octahedral array, y∼0.5. The electrical consequences of these structural changes observed in this system are qualitatively explained with electronic structure calculations, this behavior agrees very well with those observed in other pyrochlore systems A 2 M 2O7 (A=rare earth cations or Tl+, Pb2+, or Bi3+, and M=Ru or Ir). [Copyright &y& Elsevier]

Abstract: The passage of swift heavy ions through dielectric layers (SiO2 or SiON) on silicon, creates ion tracks in them. After the etching and filling of these ion tracks with a suitable material, a novel electronic structure acronymed TEMPOS – ‘Tunable Electronic Materials with Pores in Oxide on Silicon’ has been realized. Several electronic devices, both, active and passive, have been fabricated and systematically studied in the last few years. Sensors have also been successfully made and characterized using the TEMPOS structure as it offers a high surface to volume ratio resulting in fast response time and high sensitivity of the sensor. In continuation with these studies, in the present paper, ferrofluids have been inserted in the ion tracks to study their behaviour in confined geometry and for subsequently obtaining magnetic sensors. A comparative study has been done between the aqueous and non-aqueous ferrofluids. Insertion of the ferrofluids in the ion tracks exhibits a change in the I–V behaviour in the presence of a magnetic field which can be exploited for obtaining the above said sensor. [ABSTRACT FROM AUTHOR]

Abstract: Calcium aluminates, compounds in the CaO–Al2O3 phase system, are used in high-temperature cements and refractory oxides and have wide range of potential technological applications due to their interesting optical, electrical, thermal, and mechanical properties. They are used in both crystalline and glassy form; the glass is an isotropic material while the crystalline materials may be highly anisotropic. This paper will consider two particular crystalline materials, CA2 and CA6, but the results should be applicable to all calcium aluminates. Although CA2 and CA6 crystals contain the same chemical species, Ca, Al, and O, the coordination and local environments of these species are different in the two structures and hence they show very different energy-loss near-edge structures (ELNES) when examined by electron energy-loss spectroscopy (EELS) in the TEM. The data obtained using ELNES can effectively provide a fingerprint for each compound and a map for their electronic structure. Once such fingerprints are obtained, they can be used to identify nano-sized particles/grains or material at interfaces and grain boundaries. In the present study, the local symmetry fingerprints for CA2 and CA6 structures are reported combining experimental spectra with electronic-structure calculations that allow the different features in the spectra to be interpreted. Al-L2,3 and O-K edge core-loss spectra from CA2 and CA6 were measured experimentally using electron energy-loss spectroscopy in a monochromated scanning transmission electron microscope. The near-edge structures were calculated for the different phases using the orthogonalized linear combination of atomic-orbitals method, and took account of core–hole interactions. It is shown that CA2 and CA6 structures exhibit distinctive experimental ELNES fingerprints so that these two phases can be separately identified even when present in small volumes. [Copyright &y& Elsevier]

Abstract: α-Rhombohedral (α-rh) boron, which is the most stable of boron''s polymorphs at low temperatures, has p-type semiconductive properties. There have been some attempts to dope the interstitial sites with alkali atoms to create metallic or n-type semiconductive α-rh boron, but this has yet to be achieved. In a previous work, we proposed the codoping of α-rh boron with Li and P or As, and revealed from first principles calculations that B12PLi and B12AsLi could be synthesized and become narrow-gap semiconductors. The band structure suggested that the mobility of electrons might be greater than that of holes. In this paper, based on these prospective results, we selected a new combination of dopants, Li and O, and theoretically studied such compounds as B12OLi and B12O2Li. The results showed that both of these materials are metallic, while the reaction energies of the Li insertion into B12O and B12O2 are lower (more unstable) than with B12PLi and B12AsLi. It was proved that the differences in the electronic structures are caused by the dangling bonds of the dopant atoms, O, P and As. [Copyright &y& Elsevier]

Abstract: Strontium borophosphate phosphate (Sr6BP5O20, SrBP), activated by divalent europium ions is a bluish-green phosphor emitting in a broad band with the emission peak near 480nm. In this paper, we report the crystal structure of SrBP determined from an analysis of the X-ray diffraction pattern of a prismatic single crystal (size 60μm×50μm×40μm). This crystal was chosen from undoped phosphor powder samples prepared for this purpose by solid-state reaction. SrBP is observed to crystallize in a body-centered tetragonal lattice with the lattice parameters and , the associated space group being (space group 120). Using the structural data from this study, we have also calculated its electronic structure using the augmented spherical wave method and the local density approximation (LDA). We show the ordering of the electronic states by the density of states (DOS) and the partial DOS plots. The LDA gives a direct optical band gap at the Γ point of about 5eV. The significance of the crystal structure and associated electronic structure is discussed with respect to maintenance of this phosphor in Hg-discharge lamps. [Copyright &y& Elsevier]

Abstract: Theoretical study of electronic structure of antinide ions and its dependence on N and Z are presented in this paper. The main 5fN and excited 5fNn′l′N′ configurations of actinides have been studied using Hartree–Fock–Pauli approximation. Results of calculations of radial integrals and the energy of X-ray lines for all 5f ions with electronic state AC+1−AC+4 show approximate dependence on N and Z. A square of N and cubic of Z are ewalized for the primary electronic parameters of the actinides. Theoretical values of radial integrals for free actinides and for ions in a cluster AC+ n :[L] k are compared, too. [Copyright &y& Elsevier]

A series of ruthenium gallium stannides have been prepared with stoichiometry RuGavSnw, where 8+3v+4w=14 and 0

The post-transition metal cations are widely used in rechargeable batteries, solar-cells, and birefringent compounds. In this paper, the electronic structures and birefringence of ternary CsSnX 3 (X ​= ​Cl, I), CsPbX 3 (X ​= ​Cl, Br, I), and binary MX 2 (M ​= ​Sn, Pb; X ​= ​Cl, Br) compounds are investigated using the first-principles methods. The results show that these metal halides own different mechanism in stereochemical activity and birefringence, i.e., the stereochemical activity of lone-pair electrons are determined by energy difference between cation s states and halogen p states, and the stereochemical activity decreases from Cl to I. While the cation p states play an important role in determining the birefringence, and the birefringence increased from Cl to I. [Display omitted] • Electronic structures and optical properties of post-transition metal halides are investigated. • Stereochemical activity of lone-pair electrons are determined by energy difference of cation-s and halogen-p states. • Cation p states play an important role in determining the birefringence. [ABSTRACT FROM AUTHOR]

In this paper, we study theoretically the structural, electronic, optical, elastic and thermoelectric properties of MgSc 2 X 4 (X ​= ​S; Se) compounds using first-principles calculations. The calculated band structure reveals that MgSc 2 S 4 and MgSc 2 Se 4 are direct-gap semiconductors. The optical features of MgSc 2 S 4 and MgSc 2 Se 4 as functions of photon energy were calculated for energy range of 0–20 ​eV. MgSc 2 X 4 (X ​= ​S; Se) are promising optoelectronic, and thermoelectric compounds whose absorption rates can reach 4 orders of magnitude in the visible range, and 6 orders of magnitude in ultraviolet range. Both chalcogenides possess high brittleness with the Pugh's ratio (B / G), and Cauchy pressure C 12 − C 44 of 1.60 and − 4.485 GPa (for MgSc 2 Se 4); 1.61 and − 3.655 GPa (for MgSc 2 S 4). MgSc 2 S 4 and MgSc 2 Se 4 reveal similar Z T e values. The obtained properties of MgSc 2 X 4 (X ​= ​S; Se) are well confirmed by experimental results. Weighted band structures of MgSc 2 S 4 and MgSc 2 Se 4 as obtained by TB-mBJ. Image 1 • Structural, and electronic properties of MgSc 2 X 4 (X ​= ​S; Se) spinel compounds. • The distribution of the conduction bands depends on the hybridization S/Se- p orbitals and Sc- d orbitals. • High absorption rate in the visible and ultraviolet ranges. • High brittleness of MgSc 2 S 4 , and MgSc 2 Se 4. • Good thermoelectric and optoelectronic properties. [ABSTRACT FROM AUTHOR]

Both the LiVO 2 and NaVO 2 play pivotal roles in the cathode materials of Li/Na ion batteries due to their high capacity and good stability. In this paper, the electronic structures and electrochemical properties of LiVO 2 and NaVO 2 are studied by the first-principles method. The delithiation/desodiation processes are calculated and the emphasis is put on the redox processes based on the analysis of the calculated Bader charges. Results show that both the V and O ions participate in the redox reaction processes, with V ions lose much more electrons than O ions. Electronic structures, such as the electronic density of states, V–O bonding characters during the delithiation/desodiation processes are employed to comparatively study the redox processes in LiVO 2 and NaVO 2. The magnetism of Li 1- x VO 2 and Na 1- x VO 2 during the delithiation/desodiation processes are elucidated by the Stoner criterion. Contour plots of the deformation charge densities in VO 2. Image 1 [ABSTRACT FROM AUTHOR]

• HERFD-XANES can extract compositional descriptor in Cu 2 O thin films. • Edge position parameter remains robust in presence of self-absorption artefact. • Higher PEC activity is closely correlated with the amount of Cu2+ species. Cu 2 O is an attractive photocathode for important renewable energy reactions such as water splitting and CO 2 reduction. Electrodeposition is commonly used to deposit Cu 2 O films on conductive substrates due to its simplicity and consistency. However, structural descriptors, linking electrodeposition parameters, film structure and the catalytic properties are elusive. A variety of Cu 2 O films reported by many research groups would often display vastly different electronic properties and catalytic activity, while appear indistinguishable under common characterisation tools. In this work, we take a systematic look into electrochemically deposited Cu 2 O and investigate the impact of deposition parameters towards the bulk and surface chemistry of the deposited film. Specifically, we employ high resolution XANES for thorough quantitative analysis of the Cu 2 O films, alongside more common characterisation methods like XRD, SEM and Raman spectroscopy. Photoelectrochemical (PEC) studies reveal an unexpected trend, where the highest PEC activity appears to correlate with the amount of Cu2+ content. Other factors which also affect the PEC activity and stability are film thickness and crystallite grain size. Our study shows that the use of high resolution XANES, though not perfect due to possible self-absorption issue, is apt for extracting compositional descriptor in concentrated thin film samples from the pre-edge energy position analysis. This descriptor can serve as a guide for future development of more active Cu 2 O based films for wide range of PEC processes as well as for solar cell applications. [ABSTRACT FROM AUTHOR]