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Ceramic coatings are in general a kind of brittle material because they are predominantly made up of ionic crystals that avoid dislocation motion caused by lattice distortion. In this regard, a remarkable toughened ZrO2/MgO nanocomposite coating is obtained by the plasma electrolytic oxidation (PEO) process and in-situ synthesized ZrO2 with quantitative control approach. It is revealed that the toughening behavior of the ZrO2/MgO coating is related to the coordination and diversion of lattice distortion at the metallic oxide interface, which induces distinct dislocation motion at the interface. The semicoherent interface between m-ZrO2 and MgO is verified to act as a buffer to realize toughening of the nanocomposite coating through dislocation slipping induced by lattice coordinated distortion. Simultaneously, significant interfacial lattice distortion transfer and dislocation pinning are discovered at the semicoherent interface between t-ZrO2 and MgO, which are beneficial to toughness enhancement of the nanocomposite coating. The results indicate that the toughening effect occurs along with dislocation slipping and pinning caused by lattice distortion of the ZrO2/MgO semicoherent interface, which enables the toughness of novel nanocomposite coating to reach 2.7 times of the traditional PEO coating.

We propose a novel strengthening strategy that involves the introduction of a high-entropy nanoscale phase (HENP) and semicoherent refractory nanoparticle into the A2 matrix of an as-cast equimolar HfMoNbTaTi refractory high-entropy alloy (RHEA). Based on the design concept of low difference in elemental melting points, equiaxed grains with slight segregation were obtained. The HENP was characterized as a disordered near-coherent structure with a composition significantly similar to the matrix that differed from traditional coherent intermetallics. The heterogeneous nucleation was attributed to the aggregation of the largest Hf atoms and interstitial complexes in the locally distorted matrix. Moreover, the refractory nanoparticle was inferred to be hafnium nitride, possessing high thermal stability and establishing a semicoherent interface with the matrix. Notably, the interface was lined with a Ti film of one or two atomic layers. Furthermore, owing to the high melting point and precipitation strengthening, a highest yield strength (851 MPa) was obtained at 1200 °C compared with those reported cast RHEAs. At room temperature, a high yield strength (1713 MPa) was revealed mainly due to the combined effect of solid-solution strengthening and precipitation strengthening. The present study provides a new pathway for the future design of HEAs.

[Display omitted] • A toughened ZrO 2 /MgO nanocomposite coating is in-situ synthesized during the plasma electrolytic oxidation process (PEO). • The ZrO 2 /MgO toughening behavior occurs with dislocation slipping and pinning caused by semicoherent interface lattice distortion. • The toughness (K IC) of the ZrO 2 /MgO nanocomposite coating is 2.7 times that of the traditional PEO coating. Ceramic coatings are in general a kind of brittle material because they are predominantly made up of ionic crystals that avoid dislocation motion caused by lattice distortion. In this regard, a remarkable toughened ZrO 2 /MgO nanocomposite coating is obtained by the plasma electrolytic oxidation (PEO) process and in-situ synthesized ZrO 2 with quantitative control approach. It is revealed that the toughening behavior of the ZrO 2 /MgO coating is related to the coordination and diversion of lattice distortion at the metallic oxide interface, which induces distinct dislocation motion at the interface. The semicoherent interface between m-ZrO 2 and MgO is verified to act as a buffer to realize toughening of the nanocomposite coating through dislocation slipping induced by lattice coordinated distortion. Simultaneously, significant interfacial lattice distortion transfer and dislocation pinning are discovered at the semicoherent interface between t-ZrO 2 and MgO, which are beneficial to toughness enhancement of the nanocomposite coating. The results indicate that the toughening effect occurs along with dislocation slipping and pinning caused by lattice distortion of the ZrO 2 /MgO semicoherent interface, which enables the toughness of novel nanocomposite coating to reach 2.7 times of the traditional PEO coating. [ABSTRACT FROM AUTHOR]

Heterogeneous photocatalysts are extensively used to achieve interfacial electric fields for acceleration of oriented charge carrier transport and further promotion of photocatalytic redox reactions. Unfortunately, the incoherent interfaces are almost present in the heterostructures owing to large lattice mismatch accompanied by the interfacial defects and high density of gap states, acting as high energy barriers for charge migration. In this work, we report the atomic engineering of CsPbBr 3 /PbSe heterogeneous interfaces and conversion from incoherent features to semicoherent characters via methyl acetate (MeOAc) purification of CsPbBr 3 quantum dots (QDs) before composited with two-dimensional (2D)-PbSe, which is confirmed by high-resolution transmission electron microscopy. The photocatalytic performances and theoretical calculations indicate that semicoherent interfaces are favorable for improving the activity and reactivity of the heterostructure, triggering 3 times enhanced photocatalytic CO 2 reduction rate with 91% selectivity and satisfactory stability. This study proposes a facile method for photocatalytic heterojunctions to transform incoherent interfaces to photocatalytically beneficial semicoherent boundaries, accompanying with a systematic analysis of the consequent chemical dynamics to demonstrate the mechanism of the semicoherent interface for supporting photocatalysis. The understandings gained from this work are valuable for rational interfacial lattice engineering of heterogeneous photocatalysts for efficient solar fuel production.

[Display omitted] • A parameter of segregation tendency, δ T m , was proposed for designing HEAs. • A disordered high-entropy nanoscale phase with homogeneous distribution was introduced in as-cast HfMoNbTaTi RHEA. • A semicoherent refractory nanoparticle lined with a Ti film was observed. • Precipitation strengthening via dislocation shearing mode was investigated based on both observations and calculations. • An ultrahigh yield strength (851 MPa) at 1200 °C was obtained in as-cast condition. We propose a novel strengthening strategy that involves the introduction of a high-entropy nanoscale phase (HENP) and semicoherent refractory nanoparticle into the A 2 matrix of an as-cast equimolar HfMoNbTaTi refractory high-entropy alloy (RHEA). Based on the design concept of low difference in elemental melting points, equiaxed grains with slight segregation were obtained. The HENP was characterized as a disordered near-coherent structure with a composition significantly similar to the matrix that differed from traditional coherent intermetallics. The heterogeneous nucleation was attributed to the aggregation of the largest Hf atoms and interstitial complexes in the locally distorted matrix. Moreover, the refractory nanoparticle was inferred to be hafnium nitride, possessing high thermal stability and establishing a semicoherent interface with the matrix. Notably, the interface was lined with a Ti film of one or two atomic layers. Furthermore, owing to the high melting point and precipitation strengthening, a highest yield strength (851 MPa) was obtained at 1200 °C compared with those reported cast RHEAs. At room temperature, a high yield strength (1713 MPa) was revealed mainly due to the combined effect of solid-solution strengthening and precipitation strengthening. The present study provides a new pathway for the future design of HEAs. [ABSTRACT FROM AUTHOR]

Metal halide perovskites with direct band gap and strong light absorption are promising materials for harvesting solar energy; however, their relatively narrow band gap limits their redox ability when used as a photocatalyst. Adding a second semiconductor component with the appropriate band structure offsets can generate a Z-scheme photocatalytic system, taking full advantage of the perovskite's intrinsic properties. In this work, we develop a direct Z-scheme photocatalyst based on formamidinium lead bromide and bismuth tungstate (FAPbBr 3 /Bi 2 WO 6 ) with strong redox ability for artificial solar-to-chemical energy conversion. With desirable band offsets and strong joint redox potential, the dual photocatalyst is shown to form a semicoherent heterointerface. Ultrafast transient infrared absorption studies employing selective excitation reveal synergetic photocarrier dynamics and demonstrate Z-scheme charge transfer mechanisms. Under simulated solar irradiation, a large driving force photoredox reaction (∼2.57 eV) of CO 2 reduction coupled with benzyl alcohol oxidation to benzaldehyde is achieved on the Z-scheme FAPbBr 3 /Bi 2 WO 6 photocatalyst, harnessing the full synergetic potential of the combined system.

Nanoprecipitates play a significant role in the strength, ductility, and damage tolerance of metallic alloys through their interaction with crystalline defects, especially dislocations. However, the difficulty of observing the action of individual precipitates during plastic deformation has made it challenging to conclusively determine the mechanisms of the precipitate-defect interaction for a given alloy system and presents a major bottleneck in the rational design of nanostructured alloys. Here, we demonstrate the in situ compression of core-shell nanocubes as a promising platform to determine the precise role of individual precipitates. Each nanocube with a dimension of ∼85 nm contains a single spherical precipitate of ∼25 nm diameter. The Au-core/Ag-shell nanocubes show a yield strength of 495 MPa with no strain hardening. The deformation mechanism is determined to be surface nucleation of dislocations which easily traverses through the coherent Au-Ag interface. On the other hand, the Au-core/Cu-shell nanocubes show a yield strength of 829 MPa with a pronounced strain hardening rate. Molecular dynamics and dislocation dynamics simulations, in conjunction with TEM analysis, have demonstrated the yield mechanism to be the motion of threading dislocations extending from the semicoherent Au-Cu interface to the surface, and strain hardening to be caused by a single-armed Orowan looping mechanism. Nanocube compression offers an exciting opportunity to directly compare computational models of defect dynamics with in situ deformation measurements to elucidate the precise mechanisms of precipitate hardening.