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We report a new two-dimensional compound, Pb[sub 3-x]Sb[sub 1+x]S[sub 4]Te[sub 2-δ], that has a charge density wave (CDW) at room temperature. The CDW is incommensurate with q-vector of 0.248(6)a* + 0.246(8)b* + 0.387(9)c* for x = 0.29(2) and δ = 0.37(3) due to positional and occupational long-range ordering of Te atoms in the sheets. The modulated structure was refined from the single-crystal X-ray diffraction data with a superspace group P1(αβγ)0 using (3 + 1)-dimensional crystallography. The resistivity increases with decreasing temperature, suggesting semiconducting behavior. The transition temperature (T[sub CDW]) of the CDW is ∼345 K, above which the Te square sheets become disordered with no q-vector. First-principles density functional theory calculations on the undistorted structure and an approximate commensurate supercell reveal that the gap is due to the structure modulation. [ABSTRACT FROM AUTHOR]

Two chromium chalcogenide Cs[Cr(en)2GeSe4] (1) and Cs[Cr(en)2SnSe4] (2) have been synthesized by a solvothermal method. Both compounds crystallize in the monoclinic space group P21/n. The structures of the two compounds are characterized by isolated [Cr(en)2MSe4]− clusters separated by Cs+ ions. The optical properties of the two compounds were measured which indicate a similar band gap of 1.58 eV. DFT calculations demonstrated that the valance band maximum (VBM) consist of Cr 3d orbitals and Se 4p orbitals while the conductive band minimum (CBM) are composed of Cr 3d orbitals for both compounds, which explains their similar optical band gap energies. Both compounds possess paramagnetic behaviors with the effective magnetic moment of 3.97μB for Cs[Cr(en)2GeSe4] and 3.91μB for Cs[Cr(en)2SnSe4], respectively. Field-dependent magnetization measurements demonstrated their potential as magnetocaloric materials, with the magnetic entropy change of 11.6 J (kg K)−1 for Cs[Cr(en)2GeSe4], and 14.2 J (kg K)−1 for Cs[Cr(en)2SnSe4]. [ABSTRACT FROM AUTHOR]

Polycrystalline Sn 0.8 In 0.2 Te 1– x Se x ( x =0–0.3) were prepared by conventional solid-sate reaction method, and the superconductivity was investigated in details. All the samples were crystallized in a cubic Fm 3 − m structure, which was confirmed by the XRD results. The superconducting transition temperature ( T c ) increases with increasing the Se doping level, achieving a maximal T c of 3.9 K at x =0.15 compared with 3.1 K for Sn 0.8 In 0.2 Te. The critical fields were also improved by introducing smaller Se 2− into the Te site. Our results suggest that the proper lattice shrinkage enhances superconductivity in the Sn 0.8 In 0.2 Te system. [ABSTRACT FROM AUTHOR]

A simple, safe, and clean molecular precursor-based solution method was developed to fabricate a Cu(In,Ga)(S,Se)2 absorber layer. Low-cost and versatile thioacetic acid was deployed as an effective solvent and suitable sulfur source to dissolve the starting materials, generating a high power conversion efficiency of 8.6% in the final cell. [ABSTRACT FROM AUTHOR]

Friction and wear seriously affect the performance, service life and stability of metal moving parts. In this work, a novel GO composite film grafted with POCl 3 was fabricated on metal substrates, including SS, Ti and Al. These films showed excellent tribological properties, including high carrying capacity, low friction coefficient (COF) and low wear volume on the macroscale. A tribofilm composed of GO nanoflakes and metallic phosphate was formed in the wear track of SS substrate. In addition, amorphous carbon and metallic phosphate were the main components of the transfer layer formed on the surface of the steel ball. The excellent tribological properties were dominated by GO, and the great wear resistance was attributed to the formation of metallic phosphates during the friction process. Simulation results showed that the oxygen of metallic phosphate was derived from GO modified with POCl 3 rather than air. Taking the synergistic effect of GO and POCl 3 into account when designing nanocomposite films is of great value in industrial applications. • GO composite films was assembled on stainless steel (SS), titanium alloy (Ti) and aluminum alloy (Al). • GO-based composite films grafted with POCl 3 exhibited the best tribological performance. • A tribofilm and a transfer layer were formed in the wear track of SS substrates and steel balls. • The calculation results confirmed that the synergistic effect of GO and POCl 3. [ABSTRACT FROM AUTHOR]

CuInTe2/graphene composites were fabricated by spark plasma sintering and their thermoelectric properties were investigated. Embedding graphene sheets into CuInTe2 led to decreased thermal conductivity, which can be ascribed to the enhanced phonon scattering by the interface between graphene and the matrix. An improved dimensionless figure of merit (ZT) of 0.40 at 700 K was achieved in a CuInTe2/graphene composite with a mass ratio of 80 : 1. [ABSTRACT FROM AUTHOR]

An intermediate-band (IB) semiconductor CuGa1− xCr xS2 was investigated by the self-consistent many-body GW approach (sc GW) and further confirmed by the experimental results. The Cr dopant introduced a partially occupied IB, and the density-of-states analysis indicates the electron transfer between the impurities and host lattice would suppress the non-radiative recombination. The CuGa1− xCr xS2 was synthesized by a high-temperature solid-state reaction and the X-ray photoelectron spectroscopy (XPS) indicated the presence of Cr3+. Due to the Cr dopant, two additional absorption responses were directly observed in the UV-Vis-NIR absorption spectrum. The further photocatalytic investigations verified the IB absorptions could produce highly mobile electrons and holes to degrade dyes. This material leads to lower-energy photon absorption, which could be a promising candidate for the high-efficiency solar cells. [ABSTRACT FROM AUTHOR]

Abstract: Sm1−x/3Sc x/3FeAsO1−x F x (x=0.09–0.27) were synthesized by the mechanical alloying and subsequent low temperature rapid sintering (2h at 950°C). The superconducting transition temperature (T c) increased with the doping level of x. The optimal doping achieved a T c up to 53.5K in Sm0.93Sc0.07FeAsO0.79F0.21. The higher T c value was attributed to the increased chemical inner pressure from local lattice distortion induced by smaller-size dopants, which was further confirmed by Sm1−x Sc x FeAsO0.88F0.12 (x=0.04, 0.08, 0.12). Accordingly, larger lattice distortion can enhance the superconductivity below the doping limit. Similar phenomenon was also observed in the La1−x Y x FeAsO0.8F0.2 (x=0.4, 0.5, 0.6). [Copyright &y& Elsevier]

The article focuses on a study which examined the synthesis of novel pseudo-Fre´chet-type dendrons and their fluorescent enhancement to Eu3+ ion. Using elementary analysis, infrared (IR) spectrum, proton nuclear magnetic resonance 1H-NMR, and FAB-MS, the structure of the dendrons was characterized. It was found that the dendrons had good thermo stability and solubility.

A facile and economical MoSe2/Mo structure was in situ prepared to replace the currently preferred expensive Pt and FTO counter electrode (CE) in dye-sensitized solar cells. A power conversion efficiency of 8.13% was achieved, which is comparable to that with Pt-sputtered FTO electrode (8.06%). [ABSTRACT FROM AUTHOR]

In this study, an improved tribology test rig has been applied to conduct the study on transformation mechanism between the frictional interface under the lubrication of DOS with steel/steel contacts. The results indicated that the nature of wear debris was nano-sized Fe 3 O 4 particles coated by a great deal of carbonaceous matter, which could act as a solid lubricant on the friction interface. The wear debris filled the grooves in steel surfaces and a bright black tribofilm was generated during test. The analysis results of GC-MS showed that C–C chemical bonds of DOS molecules at the tertiary carbon were easier to break during the tribochemical reaction process, and the possible tribochemical reaction mechanism of DOS molecules in this experiment was proposed. • An improved tribology test rig has been applied to conduct the study on transformation mechanism between the frictional interface under the lubrication of DOS with steel/steel contacts. • The C–C chemical bonds of DOS molecules at the tertiary carbon were easier to break and initiate radical polymerization during the tribochemical reaction process. • The nature of wear debris was nano-sized Fe 3 O 4 particles coated by a great deal of carbonaceous matter, which showed D and G bands that were similar to graphite or DLC in the Raman spectrum. • The wear debris filled the grooves in steel surfaces and generated a bright black tribofilm, which was interpreted as the crucial reason for the excellent lubrication performance of DOS. [ABSTRACT FROM AUTHOR]

A series of graphene oxide composite lubricating films were fabricated in virtue of self-assembly technique driven by chemical bonds, which could strongly enhance interfacial interaction. The composite lubricating film Si-APS-GO-HOAF composed of GO and HFPO oligomer acid fluorides (HOAF) exhibited excellent tribological properties even immersed in 0.15 M NaCl solution for one month, attributing to strong interfacial interaction of chemical bonds and the synergistic effect of GO and HOAF. Furthermore, the outermost layer HOAF was partly adsorbed on the surface of the friction pair during the friction process and gradually formed a layer of transferred lubricating film. Surface analysis demonstrated that the formation of carbon oxide fragments and silicon oxides led to the damage of assembled layers, causing lubrication failure. • The composite lubricating film was fabricated in virtue of self-assembly technique driven by chemical bonds. • Si-APS-GO-HOAF film possesses excellent tribological property even after being immersed in NaCl solution for one month. • The synergistic effect of GO and HOAF can significantly improve the tribological performance of Si-APS-GO-HOAF film. • The synergy comes from strong interfacial interaction of chemical bonding between GO and HOAF. [ABSTRACT FROM AUTHOR]

Integrating and patterning metal halides into fibers extends their applications toward novel flexible and wearable optoelectronics, where the current relevant studies still focus on the toxic Pb halides. The Sb halides have the intrinsic merits of high stability and environmental friendliness yet remain an inclusive challenge in exploration to progress. Here, based on an idea of the selection of organic cations with large rigid and electron donor characteristics to optimize the lattice distortion and electronic environment of Sb halides, a series of novel Sb halides with different Sb‐X polyhedral configurations (seesaw dimers, square‐pyramidal, and octahedrons) are successfully obtained, achieving a maximal photoluminescence quantum yield (PLQY) of 99.3%. Due to the high solution compatibility of the as‐synthesized Sb halides, they are further assembled into solution‐processable inks, which are later processed into stable luminescent fibers by the electrospinning and facile direct ink writing (DIW) in 3D printing, respectively. The luminescent fibers are successfully used for advanced anti‐counterfeiting and information encryption. This work has developed a predictable design strategy for unknown Sb halides with efficient emissions and extended the Sb halides toward the applications in flexible optoelectronics fields. [ABSTRACT FROM AUTHOR]

Safety concerns associated with lithium batteries suggest the development of solid-state batteries as a promising variant. In this work, we doped a lithium boracite (Li4B7O12Cl) with Mg2+ to modify the Li+ sites and observed significant improvement in ionic conductivity by two orders of magnitude (from 3.03 × 10−7 S cm−1 to 2.81 × 10−5 S cm−1 at room temperature). We attribute the enhanced ion conductivity to the artificially induced Li vacancies resulting from Mg doping. The as-fabricated symmetrical battery (Li‖Li3.6Mg0.2B7O12Cl‖Li) exhibited good cycling performance with a stable voltage output even after 60 hours of cycling. The battery showed a coulombic efficiency retention of ∼99.7% after the cycling test. Our work demonstrates that Li4B7O12Cl is a superior solid electrolyte for solid-state batteries and the introduction of Li vacancies can be an efficient approach to greatly improve the ionic conductivity of other electrolytes. [ABSTRACT FROM AUTHOR]