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In as-grown bulk crystals of Fe1+yTe1-xSex with x≲0.3, excess Fe (y>0) is inevitable and correlates with a suppression of superconductivity. At the same time, there remains the question as to whether the character of the antiferromagnetic correlations associated with the enhanced anion height above the Fe planes in Te-rich samples is compatible with superconductivity. To test this, we have annealed as-grown crystals with x=0.1 and 0.2 in Te vapor, effectively reducing the excess Fe and inducing bulk superconductivity. Inelastic neutron scattering measurements reveal low-energy magnetic excitations consistent with short-range correlations of the double-stripe type; nevertheless, cooling into the superconducting state results in a spin gap and a spin resonance, with the extra signal in the resonance being short range with a mixed single-stripe/double-stripe character, which is different than other iron-based superconductors. The mixed magnetic character of these superconducting samples does not appear to be trivially explainable by inhomogeneity.

We report inelastic neutron scattering measurements of low-energy (ω10 meV) magnetic excitations in the "11" system Fe1+yTe1-xSex. The spin correlations are two-dimensional (2D) in the superconducting samples at low temperature, but appear much more three-dimensional (3D) when the temperature rises well above Tc∼15 K, with a clear increase of the (dynamic) spin correlation length perpendicular to the Fe planes. This behavior is extremely unusual; typically, the suppression of thermal fluctuations at low temperature would favor the enhancement of 3D correlations, or even ordering, and the reversion to 2D cannot be naturally explained when only the spin degree of freedom is considered. Our results suggest that the low temperature physics in the 11 system, in particular the evolution of low-energy spin excitations towards superconducting pairing, intrinsically involves changes in orbital correlations.

We have combined elastic and inelastic neutron scattering techniques, magnetic susceptibility, and resistivity measurements to study single-crystal samples of KxFe2-ySe2, which contain the superconducting phase that has a transition temperature of ∼31 K. In the inelastic neutron scattering measurements, we observe both the spin-wave excitations resulting from the block antiferromagnetic ordered phase and the resonance that is associated with the superconductivity in the superconducting phase, demonstrating the coexistence of these two orders. From the temperature dependence of the intensity of the magnetic Bragg peaks, we find that well before entering the superconducting state, the development of the magnetic order is interrupted, at ∼42 K. We consider this result to be evidence for the physical separation of the antiferromagnetic and superconducting phases; the suppression is possibly due to the proximity effect of the superconducting fluctuations on the antiferromagnetic order.

The integration of inorganic materials with biological machinery to convert plastics into fuels offers a promising strategy to alleviate environmental pollution and energy crisis. Herein, we develop a type of hybrid living material via biomineralization of CdS onto Shewanella oneidensis‐based biofilm, which is capable of sustainable hydrogen production from poly(lactic acid) (PLA) wastes under daylight. We reveal that the formed biofilm microstructure provides an independent anaerobic microenvironment that simultaneously supports cellular viability, maintains hydrogenase activity, and preserves the functional stability of CdS, giving rise to the efficient plastic‐to‐hydrogen conversion efficiency as high as 3751 μmol H2 g‐1 PLA. Besides, by genetically engineering transmembrane pili conduit and incorporating conductive nanomaterials to strengthen the electron transfer across cellular interface and biofilm matrices, we show that the conversion efficiency is further enhanced to 5862 μmol H2 g‐1 PLA. Significantly, we exhibit that a long‐term sustainable plastic‐to‐hydrogen conversion of 63 d could be achieved by periodically replenishing PLA wastes. Overall, by the synergistic integration of biotic‐abiotic characteristics the developed biofilm‐based biomineralized hybrid living material is anticipated to provide a new platform toward the efficient conversion of plastic wastes into valuable fuels, and bridge the gap between environmental contamination and green energy production. [ABSTRACT FROM AUTHOR]

In this work, (1 − x) Bi2.8La1.2Ti3O12−xBaSnO3 (x = 0.04–0.07, denoted as (1 − x)BLT–xBSN) ceramics were prepared using traditional solid-phase sintering technology at 1150 °C for 2 h. The introduction of BSN into BLT ceramics not only refines the grain, but also increases the Curie temperature (Tc), in addition to enhancing the dielectric temperature stability. In 0.95BLT–0.05BSN lead-free ceramics, the breakdown field strength reaches 210 kV/cm, and a recoverable energy storage density (Wrec) of 0.73 J/cm3 and an energy storage efficiency (η) of 86.7% are obtained. Furthermore, the 0.95 BLT–0.05 BSN ceramics showed good fatigue properties, with a 3.8% Wrec change over 106 cycles at 20 °C, and, in particular, only a 3.6% Wrec change over 106 cycles at 50 °C, demonstrating insensitivity to temperature changes. In addition, the reduction in ferroelectric polarization is attributed to the significant orbital hybridization between Bi/Ti and O atoms, along with the disorder in A/B site ionic displacements, as inferred from first-principles calculations. [ABSTRACT FROM AUTHOR]

The out‐of‐plane response of prefabricated (precast) concrete shear walls (PWs) are usually neglected in the structural designs. However, because of the relatively low stiffness and inevitable deformation of slabs, the out‐of‐plane behavior of PWs could influence the in‐plane response by causing premature failure or stability problems and affect the overall structural performance. This issue becomes significant when single‐row connections are employed because the neutral axial is shifted toward the compression side and the out‐of‐plane capacity is altered accordingly. In this study, PWs with grouted steel sleeve splices were tested under reciprocating cyclic loading. Both single‐row and paired connections were considered in test program. It was shown that all PWs suffered bending failure dominated by yielding of reinforcement at the bottom, and their load‐carrying capacity, stiffness degeneration trends were similar to the monolithic (cast‐in‐place) reference walls. Under the normalized compression of 0.12, the ductility of the prefabricated walls was 2.62 and 3.07, which was comparable to that of the reference cast‐in‐place wall (2.72). For the case that axial compression was not applied, the hysteresis curve of the PW with single‐row connection exhibited significant pinching. Nonetheless, the load‐carrying capacity of these walls did not exhibit significant drop at the end of the tests due to the lower axial compression, exhibiting high level of deformability. For both load cases, PWs with paired connection exhibited higher energy dissipation than the single‐row connected specimens. [ABSTRACT FROM AUTHOR]

Lead-free 0.96(K0.48Na0.52)(Nb0.965Sb0.035−xErx)O3-0.04(Bi0.5Na0.5)ZrO3 (KNNS0.035−xEx-BNZ) multifunctional ceramics were prepared by the conventional solid-state reaction method combined with the two-step sintering method. The results show that the ceramics doped with a moderate amount of Er3+ show good piezoelectric properties and excellent temperature stability, while displaying bright up-conversion photoluminescence. Er3+-doping shifts the orthorhombic–tetragonal phase transition temperature (TO-T) down to below room temperature and enhances the temperature stability of the ceramics. For a 0.2 mol%Er3+-doped sample, the room-temperature piezoelectric constant d33 reached 343 pC/N. The sample shows good resistance to thermal depoling as noted that the d33 value remaining at more than 95% of that at room temperature when the temperature was increased to 230 °C. Relying on the luminescence behavior of rare earth Er3+ ions, Er3+-doped samples exhibit a strong photoluminescence with a bright green up-conversion emission under excitation at 980 nm. Two green emissions, at 525 nm and 550 nm, corresponded to the transitions from 2H11/2 → 4I15/2 to 4S3/2 → 4I15/2, and a weak red emission at 660 nm was assigned to the 4F9/2 → 4I15/2 transition obtained under the excitation of a 980-nm laser. The multifunctional properties in the Er-doped samples make them promising for multifunctional device applications. [ABSTRACT FROM AUTHOR]

It has recently been demonstrated that dynamical magnetic correlations measured by neutron scattering in iron chalcogenides can be described with models of short-range correlations characterized by particular choices of four-spin plaquettes, where the appropriate choice changes as the parent material is doped towards superconductivity. Here we apply such models to describe measured maps of magnetic scattering as a function of two-dimensional wave vectors obtained for optimally superconducting crystals of FeTe1-xSex. We show that the characteristic antiferromagnetic wave vector evolves from that of the bicollinear structure found in underdoped chalcogenides (at high temperature) to that associated with the stripe structure of antiferromagnetic iron arsenides (at low temperature); these can both be described with the same local plaquette, but with different interplaquette correlations. While the magnitude of the low-energy magnetic spectral weight is substantial at all temperatures, it actually weakens somewhat at low temperature, where the charge carriers become more itinerant. The observed change in spin correlations is correlated with the dramatic drop in the electronic scattering rate and the growth of the bulk nematic response upon cooling. Finally, we also present powder neutron diffraction results for lattice parameters in FeTe1-xSex indicating that the tetrahedral bond angle tends to increase towards the ideal value upon cooling, in agreement with the increased screening of the crystal field by more itinerant electrons and the correspondingly smaller splitting of the Fe 3d orbitals.