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The bulk photovoltaic (BPV) effect of conventional ferroelectric (FE) materials has sparked a great deal of interest due to anomalous above-bandgap photovoltage. However, large bandgaps and weak photocurrents remain longstanding challenges for FE PV materials in practical applications. To address these issues, we propose a new defect-engineering strategy and demonstrate it on a narrow bandgap centrosymmetric material, BiNbO4 (BNO): the BPV effect is introduced into BNO by tuning the defect amounts, then a defect-modified homojunction structure is constructed to enhance the BPV effect. This defect engineering strategy enables synergetic effects, e.g., enhanced light absorption, FE-like depolarization field and interfacial polarization. This homojunction structure results in two-fold promotion of photovoltage and ten-fold promotion of photocurrent, compared to the defect-modified BNO sample. We believe this new strategy will break through limitations in traditional material design and pave a novel route to future multifunctional materials, especially high performance BPV materials. [ABSTRACT FROM AUTHOR]

Compounds across the Sr3Ti1−xZrxNb4O15, (0 ≤ x ≤ 1), composition range were synthesised. Structure refinements were performed against synchrotron X-ray powder diffraction data and constant wavelength and time-of-flight neutron powder diffraction data. All members of the composition range were found to form tungsten bronze type structures with orthorhombic Pna21 symmetry at RT. Variable temperature diffraction data revealed that all compositions underwent a transition to a high temperature tetragonal structure on heating, with the transition temperature increasing with the zirconium content of the sample. Variable temperature dielectric measurements were performed for both end members showing maxima in the dielectric constant coinciding with the observed phase transition temperatures. [ABSTRACT FROM AUTHOR]

Background: Interlaminar stabilization and interspinous stabilization are two newer minimally invasive methods for lumbar spine stabilization, used frequently in conjunction with lumbar decompression to treat lumbar stenosis. The two methods share certain similarities, therefore, frequently being categorized together. However, the two methods offer distinct biomechanical properties, which affect their respective effectiveness and surgical success. Objective: To compare the biomechanical characteristics of interlaminar stabilization after lumbar decompression (ILS) and interspinous stabilization after lumbar decompression (ISS). For comparison, lumbar decompression alone (DA) and decompression with instrumented fusion (DF) were also included in the biomechanical analysis. Methods: Four finite element models were constructed, i.e., DA, DF, ISS, and ILS. To minimize device influence and focus on the biomechanical properties of different methods, Coflex device as a model system was placed at different position for the comparison of ISS and ILS. The range of motion (ROM) and disc stress peak at the surgical and adjacent levels were compared among the four surgical constructs. The stress peak of the spinous process, whole device, and device wing was compared between ISS and ILS. Results: Compared with DA, the ROM and disc stress at the surgical level in ILS or ISS were much lower in extension. The ROM and disc stress at the surgical level in ILS were 1.27° and 0.36 MPa, respectively, and in ISS 1.51°and 0.55 MPa, respectively in extension. This is compared with 4.71° and 1.44 MPa, respectively in DA. ILS (2.06–4.85° and 0.37–0.98 MPa, respectively) or ISS (2.07–4.78° and 0.37–0.98 MPa, respectively) also induced much lower ROM and disc stress at the adjacent levels compared with DF (2.50–7.20° and 0.37–1.20 MPa, respectively). ILS further reduced the ROM and disc stress at the surgical level by 8% and 25%, respectively, compared to ISS. The stress peak of the spinous process in ILS was significantly lower than that in ISS (13.93–101 MPa vs. 31.08–172.5 MPa). In rotation, ILS yielded a much lower stress peak in the instrumentation wing than ISS (128.7 MPa vs. 222.1 MPa). Conclusion: ILS and ISS partly address the issues of segmental instability in DA and hypermobility and overload at the adjacent levels in DF. ILS achieves greater segmental stability and results in a lower disc stress, compared to ISS. In addition, ILS reduces the risk of spinous process fracture and device failure. [ABSTRACT FROM AUTHOR]

Reversible structural transformations of porous coordination frameworks in response to external stimuli such as light, electrical potential, guest inclusion or pressure, amongst others, have been the subject of intense interest for applications in sensing, switching and molecular separations. Here we report a coordination framework based on an electroactive tetrathiafulvalene exhibiting a reversible single crystal-to-single crystal double [2 + 2] photocyclisation, leading to profound differences in the electrochemical, optical and mechanical properties of the material upon light irradiation. Electrochemical and in situ spectroelectrochemical measurements, in combination with in situ light-irradiated Raman spectroscopy and atomic force microscopy, revealed the variable mechanical properties of the framework that were supported using Density Functional Theory calculations. The reversible structural transformation points towards a plethora of potential applications for coordination frameworks in photo-mechanical and photoelectrochemical devices, such as light-driven actuators and photo-valves for targeted drug delivery. Porous coordination frameworks that undergo reversible structural transformations are promising for sensing, switching and separations. Here, the authors report an electroactive framework that exhibits a reversible single crystal-to-single crystal double [2+2] photocyclisation, leading to property changes. [ABSTRACT FROM AUTHOR]

The argument of phase coexistence in the lead-free piezoelectric perovskite K0.5Na0.5NbO3 (KNN) has led to significant discrepancies in the interpretation of its exact crystalline structure in the literature. In this work, the structural details of hydrothermally prepared KNN nanofibres and microcubes were investigated by a combination of high resolution transmission electron microscopy (TEM), solid-state 23Na and 93Nb nuclear magnetic resonance (NMR) spectroscopy and two-dimensional 23Na 3QMAS NMR. Although powder X-ray diffraction yielded an average orthorhombic structure for both morphologies, high resolution TEM revealed mixed phases of orthorhombic (O) and monoclinic (M) symmetry with a growth direction of [001] and [110], respectively, in individual KNN nanofibres. Consistent with the TEM analysis, solid-state 23Na NMR indicated a distribution of multiple Na sites in the KNN nanofibers, which were not observed in the KNN microcubes. This study provided microscopic evidence of phase coexistence in KNN nanofibers and suggested that a two-phase concomitant state might be highly dependent on the size and morphologies of the KNN nanostructures. [ABSTRACT FROM AUTHOR]

Local strain engineering is an exciting approach to tune optoelectronic properties of materials. Two‐dimensional (2D) materials such as 2D transition metal dichalcogenides (TMDs) are particularly well‐suited for this purpose due to their high flexibility and deformability. Local strain engineering in 2D TMDs is typically achieved via strained wrinkles. Wrinkles on thick TMD layers have been reported to show interesting photoluminescence enhancement due to bandgap modulation and funneling effect. However, the wrinkles in ultrathin TMDs are not investigated because they can easily fall down to form folds. Both wrinkles and folds are achieved simultaneously in 1–3L tungsten disulfide (WS2) using a new fabrication technique. A layer‐dependent reduction in surface potential is found for both folded layers and perfect packed layers due to the dominant interlayer screening effect. The strain produced from the wrinkles modulates the semiconductive junction properties significantly. Thermoionic modeling suggests that strained (1.6%) wrinkles can lower the Schottky barrier height (SBH) by 20%. Upon illumination, SBH reduces significantly due to photogenerated carriers. This is an important advance toward controlling the optoelectronic properties of 2D TMDs via strain engineering, with applications for electronics and optoelectronics devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • H 2 foam more stable than CO 2 foam due to uniform surfactant distribution preventing H 2 aqueous entry. • H 2 foam reduces hydrogen mobility through bubble deformation and pore flow resistance. • Co-injection of H 2 and SDS solution generates stable hydrogen foam to enhance trapping in porous media. Inherent obstacles of hydrogen injection encompass preferential channeling through larger pathways, hampering microscopic sweep efficiency within porous media. This work pioneers hydrogen foam generation via co-injection with aqueous sodium dodecyl sulfate (SDS) to enhance subsurface hydrogen trapping capacity. SDS addition substantially reduces hydrogen-water interfacial tension and enhances viscoelasticity. In contrast to robust hydrogen foam stability, CO 2 foams display compromised integrity, stemming from surfactant aggregation and ensuing infiltration channels that permit aqueous phase CO 2 dissolution. Hydrogen foams conversely sustain uniform surfactant films, forestalling hydrogen ingress into water. Synergetic microfluidic and pore-scale simulations visualise mechanisms underlying intensified hydrogen capture and mobility reduction attributed to deformation and flow resistance when traversing constricted pores. Introducing the amphiphilic SDS surfactant considerably promotes hydrogen adsorption through its hydrophobic tail. Core flooding experiments quantify over 2 times hydrogen storage ratio amplification with SDS relative to sole hydrogen injection. The framework contributes pragmatic strategies to harness high-efficiency hydrogen foam for scalable clean energy storage. [ABSTRACT FROM AUTHOR]

• Aerogel nanoparticles effectively lower interfacial tension between CO 2 and crude oil. • Aerogel nanoparticles stabilize CO 2 in oil foam and reduce its mobility. • Aerogel exhibits a higher adsorption capacity for asphaltene compared to quartz sand. • Aerogel nanoparticles' pores adsorb and prevent asphaltene deposition in reservoirs. Carbon capture, utilization, and storage (CCUS) is critical for reducing CO 2 emissions and mitigating climate change. However, two major technical hurdles must be addressed for efficient implementation of CCUS. Sandpack experiments were conducted to examine the efficacy of silica aerogel nanoparticles in enhancing oil recovery and inhibiting asphaltene deposition. The nanoparticle co-injection increases oil recovery from 49.39% to 73.21% compared to sole CO 2 flooding. Meanwhile, the CO 2 sequestration rate within sandpacks rises remarkably from 45.35% to 83.37% with added nanoparticles. Additionally, produced oil asphaltene content increases from 4.33 wt% to 7.25 wt%. Experimental results show aerogel undergo flow diffusion from aqueous to oil phases, modifying interfacial properties. Aerogel-stabilized CO 2 -in-oil foams exhibit reduced interfacial tension and enhanced stability, impeding CO 2 mobility. Molecular dynamics simulations reveal aerogel pores adsorb asphaltene molecules, preventing deposition. Overall, the multifunctional capabilities of aerogel nanoparticles to modify interfaces, stabilize foams, and inhibit asphaltene deposition provide pathways for optimizing CCUS efficiency. [ABSTRACT FROM AUTHOR]