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Topotactic phase transition obtains extensive research attention due to its associated rich physics as well as a promising potential application. Particularly, the oxygen incorporation into brownmillerite oxides leads to the structural transition into perovskite oxides with distinct magnetic and electronic properties. Using brownmillerite SrCoO2.5 (BM‐SCO), two novel pathways are revealed to achieve the topotactic phase transition into its corresponding perovskite SrCoO3 (P‐SCO). It is demonstrated that by using aqueous alkali as the electrolyte during gating, the negative biased voltage triggers a rapid transition into P‐SCO, which is attributed to the presence of strong oxidizing hydroxyl radicals. While surprisingly, it is observed that the acid solution with rich protons can also trigger an unexpected phase transition from BM‐SCO into P‐SCO in a much faster manner. With density functional theory calculations, this transition is elucidated as a proton‐assist ionic disproportionation, in which the Co ions are simultaneously oxidized and reduced, while the latter one is dissolved within the solution. These case studies not only achieve a deep understanding of the structural phase transition in BM‐SCO but also shed new light on the topotactic phase transition of complex oxides. [ABSTRACT FROM AUTHOR]

Efficient wound repair with skin appendage regeneration following severe trauma poses a challenge due to the scarcity of skin grafts and decreased drug effectiveness in protease‐rich wound microenvironments. Here, a multifunctional artificial skin (NIR‐mFAS) with photothermal‐triggered drug delivery capabilities is designed to actively and comprehensively improve the regenerative potential of full‐thickness wounds. The antibacterial chitosan/silk fibroin hydrogel matrix of artificial skin, cross‐linked by electrostatic interactions, effectively encapsulates and sustains the release of epidermal growth factor (EGF) to accelerate re‐epithelialization and neovascularization by promoting the migration and proliferation of repair cells. Subsequently, the photothermal responsive polydopamine nanoparticles (PDA‐NPs) dispersed in the matrix enable precise control over the release of BMP4 under the irradiation of 1064 nm NIR, thereby inhibiting scarring by reducing myofibroblasts during the proliferative stage. Importantly, the concurrent controlled release of CHIR99021 can modulate cell fate by inducing the conversion of myofibroblasts into dermal papilla‐like cells, leading to hair follicle and sebaceous gland regeneration. The NIR‐mFAS functions as an advanced delivery system for achieving high‐quality wound healing with appendage regeneration and offers a smart therapeutic approach that can be applied to other treatments requiring coordinated delivery of multiple pharmacological agents. [ABSTRACT FROM AUTHOR]

Optical manometry is a highly promising method for measuring pressure. However, its wider application is limited by the lower sensitivity and influenced by environmental factors. Herein, multi‐mode optical pressure sensors based on Eu2+‐doped Li4SrCa(SiO4)2 phosphors suitable for a variety of complex pressure‐measuring environments are designed. The phosphors contain two separate luminescence centers at 443 nm (EuSr) and 584 nm (EuCa), respectively. In the lower pressure range, the emission peak undergoes a massive redshift of 5.19 nm GPa−1 of EuCa, which is 14× better than commercially available ruby sensors. In order to improve the pressure response range and the accuracy of pressure measurement, for the first time, a new approach in the pressure readout method in which single Eu2+ ions doping based on fluorescence intensity ratio (FIR) pressure measurement is realized in designed materials. Meanwhile, the measured full width at half maximum (FWHM) as an indicator of pressure sensor performance also reveals that the sensing performance is d FWHM/d P ≈ 1.23 nm GPa−1 and d FWHM/d P ≈ 0.84 nm GPa−1 for EuSr and EuCa positions, respectively. Additionally, the structural stability of the phosphor is confirmed by in situ Raman spectrum. The above results indicate that the Li4SrCa(SiO4)2:0.04Eu2+ phosphor is a good candidate for multi‐mode optical pressure sensors. [ABSTRACT FROM AUTHOR]

Magnetic spinel oxides have attracted extensive research interest due to their rich physics and wide range of applications. However, these materials invariably suffer suppressed magnetization, due to structural imperfections (e.g., disorder, anti‐site defects, etc.). Herein, a dramatic enhanced magnetization is obtained with an increasement of 5 µB/u.c in CoFe2O4 (CFO) through ionic liquid gating induced hydrogen doping. The intercalated hydrogen ions lead to both distinct lattice expansion of ≈0.7% and notable Fe valence state reduction through electron doping, in which ≈17% Fe3+ is reduced into Fe2+. These facts collectively trigger a site‐specific spin‐flip on tetrahedrally coordinated Co2+ sites that enhances the net ferrimagnetic moment nearly to its theoretical maximum for perfect CFO. [ABSTRACT FROM AUTHOR]

[111]‐Oriented perovskite oxide films exhibit unique interfacial and symmetry breaking effects, which are promising for novel quantum materials as topological insulators and polar metals. However, due to strong polar mismatch and complex structural reconstructions on (111) surfaces/interfaces, it is still challenging to grow high quality [111] perovskite heterostructures, let alone explore the as‐resultant physical properties. Here, the fabrication of ultrathin PbTiO3 films grown on a SrTiO3(111) substrate with atomically defined surfaces, by pulsed laser deposition, is reported. High‐resolution scanning transmission electron microscopy and X‐ray diffraction reveal that the as‐grown [111]PbTiO3 films are coherent with the substrate and compressively strained along all in‐plane directions. In contrast, the out‐of‐plane lattices are almost unchanged compared with that of bulk PbTiO3, resulting in a 4% contraction in unit cell volume and a nearly zero Poisson's ratio. Ferroelectric displacement mapping reveals a monoclinic distortion within the compressed [111]PbTiO3, with a polarization larger than 50 µC cm−2. The present findings, as further corroborated by phase field simulations and first principle calculations, differ significantly from the common [001]‐oriented films. Fabricating oxide films through [111] epitaxy may facilitate the formation of new phase components and exploration of novel physical properties for future electronic nanodevices. [ABSTRACT FROM AUTHOR]