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Abstract: A new type of flower-like ZnO nanostructure was prepared on a large scale through a very simple solvothermal method. The nanoflowers are assembled by many thin and uniform hexagonal-structured ZnO nanosheets, with a thickness of around 6nm. The growth mechanism of the nanoflowers is discussed based on the reaction conditions. Room-temperature optical measurements reveal that such ZnO nanoflowers have very strong UV bandedge emission with a large Stokes shift and an asymmetrical band profile. This luminescence characteristic may be attributed to the anisotropic energy band structure of the quantum-confined ZnO nanosheets. [Copyright &y& Elsevier]

The macroscopic physical properties of materials are determined by their crystal and electronic structures. Iridates have anomalous electronic structures because of the competition of comparable energies between the Coulomb repulsion of electrons and spin–orbit coupling. The polycrystalline Sr4Ir3O10 sample is successfully synthesized, which owns a trilayered perovskite structure using the high‐pressure and high‐temperature technique. The transmission electron microscopy studies give the structural evidence of Sr4Ir3O10 in real space experimentally. It is proved that tetragonal and orthorhombic structures with I4/mmm and Pbca space groups coexist in the polycrystalline Sr4Ir3O10 sample. [ABSTRACT FROM AUTHOR]

CsPbI3 nanocrystals (CPI NCs) have become a trending research topic due to their impressive potential in functional optoelectronic devices and optical gain applications. Their optical responses are governed by carrier dynamics, which is greatly influenced by temperature and corresponding phase structure due to the effects of inherently electron‐phonon coupling. Notably, CPI NCs have been identified to adopt an unexpectedly stable cubic phase from room temperature to liquid helium temperature. Here, using in situ cryogenic electron diffraction measurements, it is unambiguously demonstrated that CPI NCs undergo consecutive cubic‐tetragonal‐orthorhombic phase transitions from 298 to 100 K. The corresponding temperature‐dependent multiexcitonic dynamics are investigated in each phase by combining time‐resolved photoluminescence and transient absorption spectroscopy. In addition to the temperature dependency, the lifetime of both excitons and biexcitons evidently depends on the phase structures of the CPI NCs, highlighting the crucial effect of crystal structure on the carrier dynamics. Moreover, the biexciton binding energy increases with higher crystal symmetry due to the decrease of the dielectric constant. The findings shed light on the structural phase transition and its relationship to the carrier dynamics in all‐inorganic perovskite NCs, which provides critical insight into the structure‐performance relationship in CPI NCs for promising applications in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Perovskite chromate SrCrO3 containing Cr4+ ions shows anomalous electronic states and physical properties, which are believed to be related to the bonding instability, but this has not been confirmed directly in experiments up to now. In order to address this issue, the crystal structure and electronic structure of SrCrO3 are investigated by using transmission electron microscopy and first-principles calculations. The results demonstrate that there is no fourfold rotational symmetry in the selected area electron diffraction patterns along the three main zone axes of SrCrO3, which is inconsistent with an expected cubic structure. Moreover, the orientation-dependent electron energy-loss spectra demonstrate a clear correlation between the dissimilar spectra and the anisotropic effects derived from the crystal structure, and first-principles calculations support the experimental results. All this strongly supports the bonding instability of ambient pressure and temperature phase of SrCrO3 and highlights the important influence of bonding fluctuation on its electronic structure and transport properties. The influence of the core-hole effect and Hubbard potential on the theoretical spectra is further investigated. [ABSTRACT FROM AUTHOR]

With the reduction in dimensions, interesting phenomena such as charge density waves and superconductivity emerge in AMn6Bi5 (A = Na, K, Rb, Cs) quasi-one-dimensional (quasi-1D) materials. Here, we report a high-quality Mn6Bi5 single crystal induced by the high-energy focus ion beam, which owns a quasi-1D crystal structure with infinite [Mn6Bi5]∞ chains. We optimize that the structure of Mn6Bi5 using density functional theory and characterize it using scanning transmission electron microscopy, and the rotation behavior of [Mn6Bi5]∞ chains is predicted and confirmed. We illustrate the quasi-1D nature of Mn6Bi5 by the density of states and band structure calculations and predict the anisotropic resistivity. Through comparing the Fermi surfaces of Mn6Bi5 and KMn6Bi5, we point out the tendency of the transition from quasi-1D to 3D crystal in Mn6Bi5. We observe and explain the apparent blueshift in the bulk plasmon peak in Mn6Bi5 and point out the reason for forming the shoulder peak in the Mn L3 peak. [ABSTRACT FROM AUTHOR]

Due to its similar electrochemistry to that of the lithium (Li)-ion battery but the high abundance of sodium (Na) in the earth, Na-ion battery is expected to be a promising alternative of the former, especially in stationary energy storage applications. Although it has been well-known that the Na-ions can be co-intercalated in graphite in some ether-based electrolytes, a number of important questions related to the Na-ion intercalation remain unclear. In order to better understand the sodium intercalation in graphite, Na-ions were intercalated in highly oriented pyrolytic graphite (HOPG) by immersing the latter in a sodium-biphenyl-monoglyme (Na-BP-DME) solution. The staging behavior that often occurs during Li-ion intercalation in graphite was observed in the Na-intercalated HOPG, on the basis of X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) characterization. The chemical formula of the DME-Na co-intercalated HOPG was determined to be Na(DME) 2 C 26 by a combination of Fourier-transformed infrared (FTIR) and Raman spectroscopy, thermogravimetry and the above structural characterizing techniques. The negligible impact of co-intercalation on the structural integrity of HOPG demonstrates that HOPG can be a promising anode material of the Na-ion batteries. The lower coordination number between the Na + ions and DME and the interaction between DME and the graphite layers are believed to be responsible for the structural stability of the co-intercalated graphite. Finally the chemical stability of the ternary graphite intercalation compounds in air was evaluated. [ABSTRACT FROM AUTHOR]

Vacancies have been proved effective in activating the oxygen redox and stabilizing the structure of the oxide cathode materials for the Na-ion batteries, but their effect on the cathode materials of the Li-ion batteries is unclear. We herein show that they have similar effect on spinel [Li4/7Mn2/7□1/7]8a[Li4/7Mn10/7]16d[O4−x′]32e. [ABSTRACT FROM AUTHOR]

The two-dimensional hole gas (2DHG) at the polar LaAlO3/SrTiO3 interface remains elusive. Different from isostructural perovskite-type interfaces, the spinel/perovskite heterointerface of γ-Al2O3/SrTiO3 (GAO/STO) enables us to control interfacial states with sub-unit-cell precision. Herein, we present the epitaxial growth of fractionally doped GAO/STO heterointerfaces, where GAO is precisely doped on the scale of 1/4-unit-cell (0.2 nm) by ferromagnetic Fe3O4 and nonmagnetic ZnO atomic layers. Notably, the conduction of the engineered interfaces depends critically on the position of the dopant, where a coexistence of electron and hole conduction is measured at even sublayer-doped GAO/STO interfaces. First-principles density functional theory calculations indicate that electron conductivity is from the interfacial TiO2 layers of the STO substrate, while the hole conductivity is from the Zn-doped GAO film. The presence of hole conduction can be explained from the alternating structural feature of a doped layer without oxygen vacancies. This work sheds additional insight on the emergence of 2DHG at oxide interfaces and provides opportunities for atomically engineered oxide interfaces with non-isostructural layers. [ABSTRACT FROM AUTHOR]

Electron energy‐loss spectroscopy (EELS) is widely applied combining with transmission electron microscopes with high spatial resolution, but its interpretation is a challenging task. One of the reasons is that the factors affecting EELS are very complicated. In this paper, we focus on the several factors involved in density functional theory (DFT) calculations. The sensitivity of calculated energy‐loss near‐edge structure (ELNES) to spin order, pressure and on‐site Coulomb energy U has been discussed. Since EELS technique detects the local environment of atoms, the influence of spin order cannot be ignored. The chemical shifts and peak intensity of ELNES are also closely related to corresponding pressure. The correlation effects are very important for transition metal compounds and play a key role in EELS simulations. An overview of the effects of these factors on the ELNES is presented with the help of Wien2k code. The antiferromagnetic order results in the decreasing of intensities of related peaks and the moving of the peaks to high energy loss. The decreasing of lattice parameters causes the ELNES peaks to shift to high energy loss, and the peak shifts at the higher energy loss are more significant. The increase of correlation effect leads to the ELNES peaks to shift to high energy loss accompanied by the increase of the relative intensity of the peaks which locate at higher energy loss. Our work helps to understand how these factors affect EELS and to explain and predict the experimental EELS spectra. Through the discussion of these factors, we propose that some factors could not be ignored in EELS simulations. Lay description: Transmission electron microscope (TEM) is a powerful scientific instrument, which can be used for small size imaging. In recent decades, it has helped scientists to make important discoveries such as carbon nanotube and quasicrystal and has been widely used in materials science, condensed matter physics, structural biology and other fields. The principle of transmission electron microscope is similar to that of optical microscope, but its resolution is far superior to that of optical microscope. Compared with the resolution of optical microscope about 300 nm, the resolution of transmission electron microscope can reach 0.039 nm at present. In addition to excellent spatial resolution, transmission electron microscope has many functions such as structural analysis, elemental composition analysis and electronic structure analysis. TEM can be also used to carry out in situ observation and time resolution observation. Because of its several advantages mentioned above, transmission electron microscopy attracts much attention since its birth in the early 1930s. The early TEM was considered to be used only to magnify the observed object, but the electron energy‐loss spectroscopy (EELS) gives it the ability to determine the composition of the sample and analyse the electronic structure. EELS is widely applied combining with transmission electron microscopes with high spatial resolution, but its interpretation is a challenging task. One of the reasons is that the factors affecting EELS are very complicated. In this paper, we focus on several factors involved in density functional theory calculations. The sensitivity of calculated energy‐loss near‐edge structure to spin order, lattice compression and expansion, and on‐site Coulomb energy is discussed. Since EELS technique detects the local environment of atoms, the influence of spin order cannot be ignored. The chemical shift and peak intensity of EELS are also closely related to corresponding lattice parameters. The correlation effects are very important for transition metal compounds and play a key role in EELS simulations. Our work helps to understand how these factors affect EELS and to explain and predict the experimental EELS spectra. Through the discussion on these factors, we provide a useful guidance for more precise EELS simulations. [ABSTRACT FROM AUTHOR]

The effect of antisite defects and their density on monolayer hexagonal boron nitride is discussed in detail. Different supercell sizes to simulate different defect densities are set up. All structures containing antisites are fully optimized. It is indicated that the high density of antisite defects leads to the instability of the BB bond. The influence of supercell size on lattice structure is also summarized. Like vacancies and dopant atoms, the antisite defects also lead to the appearance of the defect energy band. Different antisite defect densities have different effects on different orbitals. Electron energy‐loss spectroscopy theoretical simulation is conducted on a single atom to analyze the influence of antisite defect density on the electronic structure of a single atom. It is shown that the high density of antisite defects makes the σ* transition of B atoms that are far away from the defect more preferred than π* transition, while it has less influence on the transition of central N atoms of the antisite defect NB because of the influence of neighboring atoms. The concentration of antisite defects plays a key role in manipulating the physical properties of monolayer hexagonal boron nitride and is helpful in expanding potential application scenarios. [ABSTRACT FROM AUTHOR]

Interface engineering is an effective and feasible method to regulate the magnetic anisotropy of films by altering interfacial states between films. Using the technique of pulsed laser deposition, we prepared La0.67Sr0.33MnO3 (LSMO) and La0.67Sr0.33MnO3/SrCoO2.5 (LSMO/SCO) films on (110)-oriented La0.3Sr0.7Al0.65Ta0.35O3 substrates. By covering the SCO film above the LSMO film, we transformed the easy magnetization axis of LSMO from the [001] axis to the [ ] axis in the film plane. Based on statistical analyses, we find that the corresponding Mn–Mn ionic distances are different in the two types of LSMO films, causing different distortions of Mn–O octahedron in LSMO. In addition, it also induces diverse electronic occupation states in Mn3+ ions. The eg electron of Mn3+ occupies 3z2 – r2 and x2 – y2 orbitals in the LSMO and LSMO/SCO, respectively. We conclude that the electronic spin reorientation leads to the transformation of the easy magnetization axis in the LSMO films. [ABSTRACT FROM AUTHOR]

• Good epitaxial growth among substrate, Cr 2 O 3 interlayer and crystalline CrO 2 film. • There is a higher oxygen concentration between the Cr 2 O 3 film and substrate. • The Cr 2 O 3 interlayer may be inevitable for generating CrO 2. Epitaxial chromium dioxide (CrO 2) film was grown on sapphire Al 2 O 3 by the chemical vapor deposition (CVD) method. The interfacial structure of the epitaxial CrO 2 was characterized by transmission electron microscopy (TEM), and the spatial distribution of the chromium valence in the film was qualitatively analyzed by electron energy loss spectroscopy (EELS). An uneven transition layer with a diffraction pattern consistent with that of Cr 2 O 3 but with an anomalously large oxygen concentration (Cr/O ≈ 0.2–0.3) was found between the CrO 2 film and the substrate. [ABSTRACT FROM AUTHOR]

We synthesized Nb x Mo 1-x O 2 series compounds and determined the structure of each component through x-ray diffraction and selected area electron diffraction techniques. For x=0.05, 0.1, 0.2, they possess room temperature MoO 2 monoclinic structure (P 2 1 / c); for x=0.25, 0.3, they become to body-centered tetragonal structure (I 4 1 / a); for x=0.33, 0.6, 0.65, they further turn to TiO 2 rutile-type structure (P 4 2 / mnm). Nb 0.25 Mo 0.75 O 2 has transport and magnetic properties similar to those of NbMoO 4 as paramagnetic metal. Moreover, the UV–vis spectra indicate the metallic property of Nb 0.05 Mo 0.95 O 2 , Nb 0.25 Mo 0.75 O 2 , and Nb 0.6 Mo 0.4 O 2. X-ray absorption spectra at the Mo-L 3 and Nb-L 3 edges present Mo4+/Nb4+ and Mo4+/Nb5+ valence state for Nb 0.25 Mo 0.75 O 2 and Nb 0.05 Mo 0.95 O 2 , respectively. This means the latter can be descripted as Nb 0.05 Mo 0.95 O 2+δ with δ = 0.025. We synthesized a series of compounds Nb x Mo 1-x O 2 and identified the different structures corresponding to various components through XRD analyses and SAED experiments. Furthermore, we conducted physical property studies on the compounds with different compositions. [Display omitted] • Successfully synthesized Nb x Mo 1-x O 2 , including unreported components. • Nb x Mo 1-x O 2 has diverse structures with different chemical contents. • Determining the transport properties of Nb x Mo 1-x O 2. [ABSTRACT FROM AUTHOR]

Layered transition metal (TM) oxides have aroused enormous interest in both fundamental and applied cathode material research in the context of high energy‐density batteries. Although various mechanisms have been proposed to explain their significant initial capacity losses, the effect of the local structural defects on performance has been largely ignored. Herein, the stacking faults are visualized and their presence is correlated with the incomplete phase transition in Li2RuO3 to understand the significant abnormal capacity loss in the first cycle. The comprehensive performance evaluation, physical characterization and theoretical calculations indicate that the two types of stacking faults, the [100]//[11¯0] boundaries and the [110]//[11¯0] boundaries, lead to sluggish lithium diffusion and increasing stacking faults deteriorates the lithium insertion dynamics. These findings are helpful to understand the performance degradation of the layer‐structured oxides in which the anionic redox or the transition metal migration is not involved in electrochemical reactions. It is hoped that this research will also inspire new ideas for designing novel cathode materials and for improving the performance of existing materials by tuning the local structures or minimizing the local structural defects. [ABSTRACT FROM AUTHOR]

Given the consensus that pressure improves cation ordering in most of known materials, a discovery of pressure‐induced disordering could require recognition of an order–disorder transition in solid‐state physics/chemistry and geophysics. Double perovskites Y2CoIrO6 and Y2CoRuO6 polymorphs synthesized at 0, 6, and 15 GPa show B‐site ordering, partial ordering, and disordering, respectively, accompanied by lattice compression and crystal structure alteration from monoclinic to orthorhombic symmetry. Correspondingly, the long‐range ferrimagnetic ordering in the B‐site ordered samples are gradually overwhelmed by B‐site disorder. Theoretical calculations suggest that unusual unit‐cell compressions under external pressures unexpectedly stabilize the disordered phases of Y2CoIrO6 and Y2CoRuO6. [ABSTRACT FROM AUTHOR]

Given the consensus that pressure improves cation ordering in most of known materials, a discovery of pressure‐induced disordering could require recognition of an order–disorder transition in solid‐state physics/chemistry and geophysics. Double perovskites Y2CoIrO6 and Y2CoRuO6 polymorphs synthesized at 0, 6, and 15 GPa show B‐site ordering, partial ordering, and disordering, respectively, accompanied by lattice compression and crystal structure alteration from monoclinic to orthorhombic symmetry. Correspondingly, the long‐range ferrimagnetic ordering in the B‐site ordered samples are gradually overwhelmed by B‐site disorder. Theoretical calculations suggest that unusual unit‐cell compressions under external pressures unexpectedly stabilize the disordered phases of Y2CoIrO6 and Y2CoRuO6. [ABSTRACT FROM AUTHOR]

Lithium‐rich layered oxides are promising candidate cathode materials for the Li‐ion batteries with energy densities above 300 Wh kg−1. However, issues such as the voltage hysteresis and decay hinder their commercial applications. Due to the entanglement of the transition metal (TM) migration and the anionic redox upon lithium extraction at high potentials, it is difficult to recognize the origin of these issues in conventional Li‐rich layered oxides. Herein, Li2MoO3 is chosen since prototype material to uncover the reason for the voltage hysteresis as the TM migration and anionic redox can be eliminated below 3.6 V versus Li+/Li in this material. On the basis of comprehensive investigations by neutron powder diffraction, scanning transmission electron microscopy, synchrotron X‐ray absorption spectroscopy, and density functional theory calculations, it is clarified that the ordering–disordering transformation of the Mo3O13 clusters induced by the intralayer Mo migration is responsible for the voltage hysteresis in the first cycle; the hysteresis can take place even without the anionic redox or the interlayer Mo migration. A similar suggestion is drawn for its iso‐structured Li2RuO3 (C2/c). These findings are useful for understanding of the voltage hysteresis in other complicated Li‐rich layered oxides. [ABSTRACT FROM AUTHOR]

Studies the high-pressure and high-temperature synthesis of a single-phase sample of MgB[sub2]. Superconductivity of the compound; Usage of X-ray diffraction and Rietveld analysis; Identification of the structure of the sample.

Transport of intensity equation (TIE) has been applied to process the simulated and experimental images of the magnetic hard nanobubbles, which were acquired using a Lorentz transmission electron microscope. Systematic studies demonstrated that the processing parameter in TIE can modulate the features of the retrieved magnetization and induce the bi-spiral structures which may be identified as bi-skyrmions. [ABSTRACT FROM AUTHOR]

The interfacial coupling between electron correlated complex oxides opens a promising avenue for achieving new forms of magnetism that arises as a consequence of charge transfer, orbital reconstruction and symmetry-breaking. Herein we reported a distinct magnetic structure in La2/3Sr1/3MnO3 (LSMO) film sandwiched between La1/2Sr1/2CoO2.5+δ (LSCO) bilayer grown on (001)-oriented SrTiO3 substrates. It is found that the LSMO layer of heterostructure contains two independent components that are respectively free layer (free-LSMO) and coupled layer with LSCO (coupled-LSMO). The easy axis of the free-LSMO is in-plane, while it is out-of-plane directed for the coupled-LSMO layer. The thickness of these two parts in the LSMO layer are 4uc and 12uc respectively. This is in sharp contrast to the single LSMO layer on STO, for which the easy axis is always in film plane. Different from LSMO, the easy axis of LSCO is in-plane and is ferromagnetically coupled with LSMO. This distinct magnetic structure could be ascribed to orbital reconstruction due to symmetry-mismatch at interfaces. [ABSTRACT FROM AUTHOR]

Among transition-metal nitrides, the mononitride γ-MoN with a rock-salt structure has drawn particular attention because it has been predicted to possess excellent mechanical and electronic properties, especially the high superconducting temperature around 30 K. However, synthesis of bulk γ-MoNx with the nitrogen concentration, x, more than 0.5 is still challenging, leading to contradictions on its phase stability and properties. In this work, we formulated a high-pressure synthesis reaction for the formation of single-crystal γ-MoNx with a remarkably high nitrogen concentration value of x ≈ 0.67. This nitride possesses a high asymptotic hardness of ∼24 GPa, which is so far the second hardest among metal nitrides. Impressively, the expected superconductivity is absent in the as-synthesized product. We further performed density functional theory calculations to clarify the structural stability and the absence of superconductivity in stoichiometric γ-MoN. We find that the ground state of γ-MoN is theoretically explored to be a Mott insulator with an antiferromagnetic phase, while a paramagnetic configuration is adopted at the ambient conditions. Such magnetic properties would explain the structural stability and the absence of superconductivity in the as-synthesized γ-MoNx with a high nitrogen concentration. [ABSTRACT FROM AUTHOR]

Abstract: The Li‐rich layer‐structured oxides are regarded one of the most promising candidates of cathode materials for high energy‐density Li‐ion batteries. However, the uninterrupted migration of the transition metal (TM) ions during cycling and the resultant continuous fading of their discharge potentials bring challenges to the battery design and impede their commercial applications. Various efforts have been taken to suppress the migration of the TM ions such as surface modification and elemental substitution, but no success has been achieved to date. Another strategy hereby is proposed to address these issues, in which the TM migration is promoted and the layered material is transformed to a rocksalt in the first few charge/discharge cycles by specially designing a novel Li‐rich layer‐structured Li1.2Mo0.6Fe0.2O2 on the basis of density functional theory calculations. With such, the continuous falling of the discharge potential is detoured due to enhanced completion of the cation mixing. In‐depth studies such as aberration‐corrected scanning transmission electron microscopy confirm the drastic structural change at the atomic scale, and in situ X‐ray absorption spectroscopy and Mössbauer spectroscopy clarify its charge compensation mechanism. This new strategy provides revelation for the development of the Li‐rich layered oxides with mitigated potential decay and a longer lifespan. [ABSTRACT FROM AUTHOR]

In this paper, scanning transmission electron microscopy is used to study the microstructures of the defects in LaCoO 3 /SrRuO 3 multilayer films grown on the SrTiO 3 substrates, and these films have different thickness of SrRuO 3 (SRO) layers. Several types of Ruddlesden-Popper (R.P.) faults at an atomic level are found, and these chemical composition fluctuations in the growth process are induced by strain fields originating from the film-film and film-substrate lattice mismatches. Furthermore, we propose four types of structural models based on the atomic arrangements of the R.P. planar faults, which severely affect the functional properties of the films. [ABSTRACT FROM AUTHOR]

Manganese bromide has attracted enormous attention for its applications in the syntheses of organic-inorganic hybrid compounds. A complete understanding of structural and chemical stabilities of MnBr 2 is important for controlling its properties. Here, we focus on the irradiation resistance of MnBr 2 . The chief purpose of this research is reached by in situ transmission electron microscopy. It is demonstrated that the deliquescent MnBr 2 powder is prone to adsorb the vapor in air, and the hydrous MnBr 2 can be decomposed under its continuous exposure to electron beam, indicated by a transmission electron microscope via the catalysis of Cu grid at room temperature. [ABSTRACT FROM AUTHOR]

Integration of oxides with Si opens promising opportunities for novel multifunctional devices and new applications. To optimize the device performances through the hybrid integration, keeping the oxide/Si interface abrupt is critically important and challenging due to the seemingly unavoidable formation of amorphous SiO x or silicide interfacial layers. Here, we report an interface-engineering approach to this issue by molecular beam epitaxy. A BeO thin layer (∼5 nm) was deposited on Si (111) surface using a two-step process of Be deposition and oxidation. The initially formed BeO served as a template for subsequent homo-epitaxial growth of a 10-nm crystalline BeO layer. The well-defined interface between BeO and Si is clearly discerned by high-resolution transmission electron microscopy, implying the role of crystalline BeO as a barrier layer against oxygen atoms' diffusion. High-resolution X-ray photoelectron spectroscopy further confirmed that the combined BeO layers sufficiently protect the Si surface from oxidation. A bottom-gate enhancement-mode thin film transistor was established on a ZnO (130 nm)/BeO (70 nm)/Si architecture, where BeO was functionalized both as a diffusion barrier and as a high- k gate insulator. It indicates that this methodology can be potentially extended to hybrid integration of other technologically important crystalline oxides with Si infrastructures. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO 2 ) has been widely investigated as a photocatalyst material because of its stability and hypotoxicity. However, the photocatalytic activity of TiO 2 is suppressed by the large band gap and the high recombination rate of the charge carrier, which leads to confined application. Moreover, how to improve photocatalytic H 2 production without any co-catalyst remains a big challenge. Here, we report a conceptual strategy in a core–shell nanostructure of simultaneously reducing the band gap and the charge carrier recombination rate by introducing a carbon-doped porous TiO 2 layer onto a metallic TiC nanostructure using a facile in situ thermal growth method. TiC@C-TiO 2 core–shell nanostructure materials have higher photocatalytic activity in methanol aqueous solution than those of pure P25 and carbon-doped TiO 2 , which results from enhanced visible light absorption, drastic charge transfer, and the large surface area. Notably, the novel core–shell nanostructures still exhibit excellent photocatalytic H 2 production without Pt co-catalyst. The results demonstrate that TiC is an ideal support for TiO 2 photocatalysts, and this novel core–shell nanostructure can significantly shift the position of the band edge of the obtained material. This study presents a design principle for photocatalytic materials as highly efficient visible light photocatalysts. [ABSTRACT FROM AUTHOR]

A novel electrolyte materials of introducing detonation nanodiamond (DNDs) into samarium doped ceria (SDC) is reported here. 1%wt. DNDs doping SDC (named SDC/ND) can enlarge the electrotyle grain size and change the valence of partial ceria. DNDs provide the widen channel to accelerate the mobility of oxygen ions in electrolyte. Larger grain size means that oxygen ions move easier in electrolyte, it can also reduce the alternating current (AC) impedance spectra of internal grains. The lower valence of partial Ce provides more oxygen vacancies to enhance mobility rate of oxygen ions. Hence all of them enhance the transportation of oxygen ions in SDC/ND electrolyte and the OCV. Ultimately the power density of SOFC can reach 762 mw cm −2 at 800 °C (twice higher than pure SDC, which is 319 mw cm −2 at 800 °C), and it remains high power density in the intermediate temperature (600–800 °C). It is relatively high for the electrolyte supported (300 μm) cells. [ABSTRACT FROM AUTHOR]

Three new modulated structures induced by controllable electron beam irradiation (EBI) were obtained from SrCrO 3 single crystal. The crystal and electronic structures were investigated using aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy (EELS) and ab initio calculations. The EELS results revealed that EBI induced ordered oxygen vacancies and generated modulated structures SrCrO 2.5 (I 4 /mmm), SrCrO 2.8 (C 2/ m) and SrCrO 2.67 (C 2 /m) from pristine SrCrO 3 (Pmm). The corresponding structural models were proposed and modified by ab initio calculations. Additionally, the electronic structures of the optimized modulated structures were further investigated. [Display omitted] • SrCrO 3 containing Cr4+ ions possesses anomalous electronic states and physical properties. • By using the aberration-corrected scanning transmission electron microscopy, we found that the electron beam irradiation induces three kinds of modulated structure. • Our work shows the plentiful properties of the material and deepens our understanding on this material. [ABSTRACT FROM AUTHOR]

S/Li2S phase separation at nanoscale is observed for the first time in the solid‐state Li–S battery by using in situ transmission electron microscopy. This nanophase separation not only reduces the diffusion distance but also provides the S/Li2S interfaces network, which is favorable for electron and Li+ ion transportation during the lithiation process. [ABSTRACT FROM AUTHOR]

With the assistance of in situ heating techniques in the transmission electron microscope, the morphology change of the Pt nanowires which were deposited by focus ion beam has been monitored under different temperatures. With a drastic shape expansion, a significant bending has been observed abruptly above 250 °C. The energy dispersive X-ray spectroscopy mapping indicated the asymmetrical distribution of carbon (C), platinum (Pt) and gallium (Ga) within the Pt nanowires while the diffraction analysis revealed the crystalline formation of Ga-Pt alloys during the heating process. The in-situ exploration discovered that besides the recrystallization of Pt nanoparticles, the asymmetrical volume expansion from the Ga-Pt alloys formation should be another factor which induces the shape variation of the heated Pt nanowires. [ABSTRACT FROM AUTHOR]

The commercialization of Sn-based anodes for lithium ion batteries is still hindered due to the inherent volume change leading to a rapid capacity fading during the electrochemical cycle. Inspired by echeveria , a plant that stores sufficient water in its hierarchical leaves to survive in a drought, we report a breakthrough by designing the hierarchical and nanoporous SnO 2 electrode encapsulated with ultrathin carbon layer (∼2 nm). As evidently captured by in situ transmission electron microscopy, the conformal carbon coating on the surface of anode may provide an elastic cover that suppresses the cracks due to severe volume change, and increases both electrical and ionic conductivity, allowing the cells to exhibit excellent lithium storage performance with more than 800 cycles even with relatively high-rate of current densities. [ABSTRACT FROM AUTHOR]

The orthorhombic (3/2, 2/1) approximant with a = 3.06 nm, b = 1.23 nm, c = 2.24 nm, and the coexisting (2/1, 3/2) approximant of decagonal quasicrystals with a = 1.90 nm, c = 3.64 nm, and β ≅ 90° are found in Al–Cr–Fe–Si alloys by aberration-corrected transmission electron microscope. The structural relationships of these two approximants are analyzed and discussed based on the high-angle annular dark-field scanning transmission electron microscopy images at atomic resolution. We find that both of their structural tiling along the [010] direction can be described by one shield-like tile, with the superiority over the previous HBS tiling model due to the clarity. Combining the shield-like tile and HBS tiling model, the domains of approximants are clearly demonstrated. [ABSTRACT FROM AUTHOR]

ZnS nanotetrapods synthesized via a solvothermal route have a octahedral core with a zincblende (ZB) structure and four hexprism-shaped arms consisting of alternately stacking ZB and wurtzite (WZ) phases, where the WZ phase has a higher volume percentage.In situangular-dispersive X-ray diffraction (ADXRD) measurements were carried out to study the structural behavior of ZnS nanotetrapods under high pressure up to 41.3 GPa. The initial WZ structure exhibits a very high mechanical stability to ∼11.3 GPa. Both the WZ and ZB structures transform to the rocksalt (RS) structure at ∼15.4 GPa. The bulk moduli of the WZ (148.2 ± 8.9 GPa) and RS (165.6 ± 9.9 GPa) phases are both larger than the previously reported values. These phenomena are discussed based on the alternating epitaxial growth of the WZ and ZB phases in the arms of nanotetrapods. Our study suggests that the internal structure of nanomaterials could also greatly affect their stability and transition behavior. [ABSTRACT FROM PUBLISHER]

Adipose tissue inflammation increases with obesity, but adipocyte vs. immune cell contributions are unclear. In the present study, transcriptome analyses were performed on highly-purified subcutaneous adipocytes from lean and obese women, and differentially expressed genes/pathways were determined in both adipocyte and stromal vascular fraction (SVF) samples. Adipocyte but not SVF expression of NOD-like receptor pathway genes, including NLRP3 and PYCARD , which regulate caspase-1-mediated IL-1β secretion, correlated with adiposity phenotypes and adipocyte class II major histocompatibility complex (MHCII) gene expression, but only MHCII remained after adjusting for age and body mass index. IFNγ stimulated adipocyte MHCII, NLRP3 and caspase-1 expression, while adipocyte MHCII-mediated CD4 + T cell activation, an important factor in adipose inflammation, induced IFNγ-dependent adipocyte IL-1β secretion. These results uncover a dialogue regulated by interactions among T cell IFNγ and adipocyte MHCII and NLRP3 inflammasome activity that appears to initiate and escalate adipose tissue inflammation during obesity. [ABSTRACT FROM AUTHOR]

A transition metal oxide, NbMoO 4 , is synthesized by using a solid-state reaction method, then the morphology of the sample is characterized by the scanning electron microscopy. The X-ray diffraction refinement and transmission electron microscopy results show that the sample has a TiO 2 rutile-type structure with space group P 4 2 / mnm , which is the high-temperature phase of NbO 2 and MoO 2. Our transport result indicates that the resistivity is as low as 0.02 Ω·cm in the temperature range from 2 to 300 K, indicating the metallicity of NbMoO 4. Furthermore, the calculated density of states and experimental specific heat data from 2 to 20 K also confirm the metallic behavior. Our magnetization experiments indicate that the NbMoO 4 exhibits paramagnetism. The valence states of Nb4+ and Mo4+ in NbMoO 4 are revealed by the X-ray absorption spectroscopy. • We have successfully synthesized rutile-structure NbMoO 4 at room temperature, which is the high-temperature structure of NbO 2 and MoO 2. • Magnetic and transport properties of NbMoO 4 are firstly reported. • NbMoO 4 is determined as a paramagnetic metal by experiments and theoretical calculations. [ABSTRACT FROM AUTHOR]

Manganese oxides are good candidates of strongly correlated electron materials due to the uniqueness of electronic structure of manganese and the mobility of oxygen among lattice sites under external impacts. Here, we used electron beam as the excitation source to explore the structural evolution of YMnO3 and identified a new phase under the radiation of electron beam in the transmission electron microscope. Analyses of the electron energy-loss spectra reveal that this phase originates from ordered oxygen vacancy. We applied the first principles calculation to pick out the optimized stable structure with a lower polarization, and verified its correctness by electron diffraction and image simulations. Analyses of density of states indicate that weak Y- O covalence is favorable for the existence of ferroelectricity, supporting the electrostatic nature of ferroelectricity in the YMnO3. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports that the high pressure in situ angle dispersive x-ray diffraction and Raman scattering studies on CoPt and NiPt hollow nanospheres are performed by means of a diamond anvil cell for generating external pressure at room temperature. The crystal structures of both the CoPt and NiP hollow nanospheres keep stable up to about 41GPa. Moreover, it shows that the hollow nanospheres possess higher bulk moduli than their bulk counterparts by using the first-principles density functional theory. [Copyright &y& Elsevier]

The magnetic properties of hexagonal Ba(Ti1-xMnx)O3 (x = 1/9, 1/6) samples specifically treated under different thermal conditions are investigated. A magnetic transformation from paramagnetism of as-grown samples to weak ferromagnetism of post-annealed samples is observed at room temperature. Associated with the structural modulation characteristics and dielectric behaviors, our experimental results reveal that the high-temperature ferromagnetism in Mn-doped hexagonal BaTiO3 derives from RIII types of antiphase domain boundaries. Spin glass transitions are observed at Tsg = 48 K and 44 K in the densely doped as-grown and post-annealed samples, respectively, but the transitions are not intrinsic properties of the hexagonal phases. [ABSTRACT FROM AUTHOR]

Abstract: A simple and effective ball-milling combined calcination method has been developed to prepare MoS2/CdS photocatalysts for visible-light-driven water splitting into H2 for the first time. The photocataysts exhibit very high photocatalytic activities. A H2 evolution rate up to 1315μmolh−1 has been achieved based on 0.9mol% MoS2/CdS (PT) photocatalyst (PT is the abbreviation of pretreatment), which is much higher than 488μmolh−1 for the 0.2wt% Pt/CdS (PT) photocatalyst. In the meantime, this photocatalyst exhibits good anti-photocorrosion property. The ball-milling procedure makes the starting material, (NH4)2MoS4, disperse uniformly on the surface of CdS nanoparticles. Further calcination treatment leads to complete decomposition of (NH4)2MoS4 to afford MoS2/CdS photocatalysts with intimate contacts between the two components. The pretreatment of CdS also has important positive effect on photocatalytic activity. Similar reactions by attempting different kinds of commercial CdS products have been carried out, indicating this preparation method is universal. [Copyright &y& Elsevier]

Abstract: Aim of the study: The purpose of this study was to evaluate the efficacy and safety of a topical Chinese herbal medicine (CHM) compound Tangzu Yuyang Ointment (TYO) for treatment of chronic diabetic foot ulcers. Materials and methods: This multi-center, prospective, randomized, controlled and add-on clinical trial was conducted at seven centers in the China mainland. Fifty-seven patients with chronic diabetic foot ulcers of Wagner''s ulcer grade 1–3 were enrolled in this study. Patients who were randomly assigned to the control group (n =28) received standard wound therapy (SWT), whereas those randomized to the treatment group (n =28) received SWT plus topical TYO. Only 48 patients who finished 24 weeks of observations were entered for data analysis. Results: The TYO and SWT groups were comparable for baseline characteristics. Ulcer improvement was 79.2% in the TYO group and 41.7% in the SWT group (P =0.017) at 12 weeks, and 91.7% vs. 62.5% (P =0.036) at 24 weeks. The number of ulcers that were completely healed at 4, 12 and 24 weeks was similar in both groups, as were the numbers of adverse events. Healing time was 96±56 days (n =19) in the TYO group and 75±53 days (n =14) in the SWT group (P =0.271). Conclusion: TYO plus SWT is more effective than SWT in the management of chronic diabetic foot ulcers and has few side-effects. [Copyright &y& Elsevier]

Abstract: Nanosintering behaviour of MgAl2O4 ultra-fine powder was investigated under high pressure. We found that the nanosintering mechanism under high pressure was quite different from that under ambient pressure. To shed light on the mechanism, the residual stress, grain size, and boundary situation were investigated using HRTEM and XRD, respectively. Our results show high pressure can restrain grain growth and initiate plastic deformation to eliminate pores and/or additional phases existing in triple junctions of the grains. However, the conventional sintering process is controlled by grain growth to avoid imperfections between grain boundaries when preparing transparent ceramics. [Copyright &y& Elsevier]

Abstract: The 6H and 6M Ba1− x SrxRuO3 at x⩽0.6 with the normal and distorted hexagonal BaTiO3 structures were synthesized by using high-pressure and high-temperature method. It is found that the unit cell volume deviates from Vegard''s law between 0.3 and 0.4 for the solid solutions due to the increasing distortion degree of crystal structure. With the increasing x, the electrical resistivity at the same temperature is increasing. With the substitution of Sr for Ba ion, the 6H BaRuO3 transforms to a Fermi-liquid metal at x=0.25 from the primal non-Fermi-liquid metal, and then becomes a semiconductor at low temperature when x is larger than 0.4. [Copyright &y& Elsevier]

Abstract: Activated carbon was treated at 5GPa up to 1600°C, and the structural evolution in the graphitization process was investigated. The graphitization temperature is equal to 1200°C at 5GPa, reflected by X-ray diffraction (XRD) patterns. Honeycomb-like structures in micron scale come into being in the high-pressure sintering temperature range of 1000−1100°C and slice-like structures appear after graphitization. The existence of D and D’ lines in the Raman spectra for the graphitized-activated carbon indicates that there are still some disordered structures. The continuous occurrence of variable-range hopping, the approximately linear ρ–T relationship, and semimetal conduction mechanism accords with the graphitization process. [Copyright &y& Elsevier]

• SCO-LSMO bilayer films are fabricated by PLD technique. • SCO has been defined to be Ima 2 structure. • Domains and stack-fault structures are detected in SCO layer. • A peculiar nanocrystalline embeds in the SCO-LSMO interface. SrCoO 3-δ (0 < δ < 0.5) film has shown great potential in applications for interface engineering of spintronic devices due to its multiformity of crystal structures and magnetic properties. In this work, we have studied the microstructures of SrCoO 3-δ in SrCoO 2.5 -La 0.67 Sr 0.33 MnO 3 (SCO-LSMO) double-layered films by using scanning transmission electron microscopy. Our fabricated SCO film is determined to have a structure with the Ima 2 space group (No. 46). Perpendicular domain and stack-fault structures are observed to coexist in the SCO layer. In the joint of domains, oxygen content remains a constant for octahedra layers but a slight rise for tetrahedra layers. Continuous changes of oxygen content are also detected in the same level layer in the stack-fault region near the domain boundary. Besides, a peculiar nanocrystalline is observed at the interface of SCO-LSMO. The electron energy-loss spectroscopy results show that the Co ions in nanocrystalline have a lower valence, indicating a chemical compositon of SrCoO 2.5-δ (0 < δ < 0.5). [ABSTRACT FROM AUTHOR]

Compared with 3 d -electron transition metal oxides (TMOs), 5 d -electron TMOs, particularly iridates, have strong competition between spin-orbit coupling and on-site Coulomb repulsion due to their comparable energies. By using aberration-corrected transmission electron microscopy, we have studied at an atomic scale the Sr 3 Ir 2 O 7 sample with a bilayered perovskite structure, which is synthesized under high pressure and high temperature. In addition, we have also investigated its magnetic and electrical properties. Our results show that the Sr 3 Ir 2 O 7 possesses two kinds of structures: a tetragonal structure (I 4 /mmm) and an orthorhombic structure (Ccce) with complex magnetic and electrical properties. We observed that there are often 90° domain structures along the b axis of the orthorhombic structure of Sr 3 Ir 2 O 7 , which might be associated with the essence of antiferromagnetic 90° domains. • Two structures, I 4/ mmm and Ccce , are found to coexist in high pressure synthesized Sr 3 Ir 2 O 7. • Sr 3 Ir 2 O 7 shows anomalous magnetic and electrical properties. • Domain structure in orthorhombic Sr 3 Ir 2 O 7 may induce the 90° antiferromagnetic domains. [ABSTRACT FROM AUTHOR]

A simple aqueous solution route has been used to prepare mercaptoacetic acid attached CuInS2 quantum dots. Based on this material, core–shell CuInS2–Mn doped CdS quantum dot sensitized solar cells are assembled and a power conversion efficiency of 5.38% is obtained under AM1.5 (100 mW cm−2) illumination. [ABSTRACT FROM AUTHOR]

Film of Fe3O4 was prepared with laser molecular beam epitaxy deposition on a Si substrate with a native SiO2 layer. When the temperature is increased above 250 K, the resistance drops rapidly because the conduction path starts to switch from the Fe3O4 film to the inversion layer underneath the SiO2 via thermally assisted tunneling. A greatly magnified low field negative magnetoresistance of Fe3O4 is observed at 280 K. The effect is similar to a metal-oxide-semiconductor field-effect transistor. The magnetoresistance becomes positive with further increase in the magnetic field due to the Lorentz force and other effects on the carriers in the inversion layer. [ABSTRACT FROM AUTHOR]

Keywords: double perovskites; lattice compression; magnetic frustration; pressure-induced B-site disorder; statistical model EN double perovskites lattice compression magnetic frustration pressure-induced B-site disorder statistical model 8378 8378 1 05/13/20 20200518 NES 200518 B Gemäß chemischer Intuition b erhöht Druck den Ordnungsgrad in den meisten Materialien. Die Entdeckung eines druckinduzierten Unordnungsprozesses in den Doppelperowskiten Y SB 2 sb CoIrO SB 6 sb und Y SB 2 sb CoRuO SB 6 sb steht im Gegensatz zu den klassischen Ordnungs/Unordnungs-Theorien und wird zu einer Neubetrachtung der Druckeffekte in den Festkörperwissenschaften führen. Double perovskites, lattice compression, magnetic frustration, pressure-induced B-site disorder, statistical model. [Extracted from the article]