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Recent realizations of ultrathin freestanding perovskite oxides offer a unique platform to probe novel properties in two-dimensional oxides. Here, we observe a giant flexoelectric response in freestanding BiFeO3 and SrTiO3 in their bent state arising from strain gradients up to 3.5 × 107 m-1, suggesting a promising approach for realizing ultra-large polarizations. Additionally, a substantial change in membrane thickness is discovered in bent freestanding BiFeO3, which implies an unusual bending-expansion/shrinkage effect in the ferroelectric membrane that has never been seen before in crystalline materials. Our theoretical model reveals that this unprecedented flexural deformation within the membrane is attributable to a flexoelectricity-piezoelectricity interplay. The finding unveils intriguing nanoscale electromechanical properties and provides guidance for their practical applications in flexible nanoelectromechanical systems.

Perovskite‐oxide‐based ferroelectric tunnel junctions (FTJs) hold great potential for applications in non‐volatile memory and neuromorphic computing due to their unique properties. However, the challenges in synthesizing high crystalline quality perovskite oxides directly on silicon wafer limit the applications of these FTJs in conventional Si‐based integrated circuits, let alone the neural networks. Herein, perovskite oxide FTJs with an ON/OFF ratio up to 1.2×106, writing/erasing speed down to 1 nanosecond, and cycling endurance (>106) are achieved by integrating ultrathin freestanding ferroelectric perovskite oxide membranes directly on silicon wafers using a wet‐transfer method. Moreover, synapses based on these FTJs exhibit long‐term plasticity. For handwritten digits recognition task, the convolutional neural network (CNN) simulation is implemented achieving a recognition accuracy up to 98.9% based on the experimental performance, close to the result of 99.2% by software‐floating‐point‐based CNN. This work sheds light on the integration of ferroelectric perovskite oxides directly on silicon for high‐performance FTJ‐based non‐volatile memory and synaptic devices. [ABSTRACT FROM AUTHOR]

Cathodic CO2 adsorption and activation is essential for high‐temperature CO2 electrolysis in solid oxide electrolysis cells (SOECs). However, the component of oxygen ionic conductor in the cathode displays limited electrocatalytic activity. Herein, stable single Ruthenium (Ru) atoms are anchored on the surface of oxygen ionic conductor (Ce0.8Sm0.2O2‐δ, SDC) via the strong covalent metal‐support interaction, which evidently modifies the electronic structure of SDC surface for favorable oxygen vacancy formation and enhanced CO2 adsorption and activation, finally evoking the electrocatalytic activity of SDC for high‐temperature CO2 electrolysis. Experimentally, SOEC with the Ru1/SDC‐La0.6Sr0.4Co0.2Fe0.8O3‐δ cathode exhibits a current density as high as 2.39 A cm−2 at 1.6 V and 800 °C. This work expands the application of single atom catalyst to the high‐temperature electrocatalytic reaction in SOEC and provides an efficient strategy to tailor the electronic structure and electrocatalytic activity of SOEC cathode at the atomic scale. [ABSTRACT FROM AUTHOR]

Redox reaction of the monovalent Rh2(CO)4Cl2 and Binn− (n = 2, 3) from K5Bi4 in ethylenediamine (en) solution produced the decabismuthide-hexarhodium dianion [Rh@Bi10(RhCO)5]2− (1a) wherein a novel Bi10-bowl was constructed from oxidized 2Bi3/2Bi2 open triangles/dimers, which was stabilized by strong bonding to a reduced Rh@(RhCO)5 square pyramid. Two 1a dianons are held together by weak interactions (van der Waals forces and spatial resistance) to form a dimer [Rh@Bi10(RhCO)5]24− (1). The structure and bonding of the novel polybismuthide heteroanion 1 are discussed. [ABSTRACT FROM AUTHOR]

Redox reaction of the monovalent Rh2(CO)4Cl2 and Binn− (n = 2, 3) from K5Bi4 in ethylenediamine (en) solution produced the decabismuthide-hexarhodium dianion [Rh@Bi10(RhCO)5]2− (1a) wherein a novel Bi10-bowl was constructed from oxidized 2Bi3/2Bi2 open triangles/dimers, which was stabilized by strong bonding to a reduced Rh@(RhCO)5 square pyramid. Two 1a dianons are held together by weak interactions (van der Waals forces and spatial resistance) to form a dimer [Rh@Bi10(RhCO)5]24− (1). The structure and bonding of the novel polybismuthide heteroanion 1 are discussed. [ABSTRACT FROM AUTHOR]

Bismuth ferrite (BiFeO3) possesses a non‐collinear spin order while the ferroelectric order breaks space inversion symmetry. This allows efficient electric‐field control of magnetism and makes it a promising candidate for applications in low‐power spintronic devices. Epitaxial strain effects have been intensively studied and exhibit significant modulation of the magnetic order in bismuthBiFeO3, but tuning its spin structure with continuously varied uniaxial strain is still lacking at this moment. Herein, in situ uniaxial tensile strain is applied to a freestanding BiFeO3 film by mechanically stretching an organic substrate. A scanning nitrogen‐vacancy (NV) microscopy is applied to image the nanoscale magnetic order in real space. The strain is continuously increased from 0% to 1.5% and four images under different strains are acquired during this period. The images show that the spin cycloid tilts by ≈12.6° when strain approaches 1.5%. A first principle calculation is processed to show that the tilting is energetically favorable under such strain. The in situ strain applying method in combination with scanning NV microscope real‐space imaging ability paves a new way in studying the coupling between magnetic order and strain in BiFeO3 films. [ABSTRACT FROM AUTHOR]

This paper analyzes how housing prices affect innovation and entrepreneurship. We construct a city-level panel dataset including 281 cities between 2009 and 2019 by merging housing price data from China Statistical Yearbook for Regional Economy with innovation and entrepreneurship data from Peking University Open Research Data Platform. Our results suggest that housing prices are positively associated with the vitality of innovation and entrepreneurship (VIE). The results remain consistent with a series of robustness checks. We also find that rising house prices promote VIE through the wealth effect and the siphon effect. Spatial effect analysis further shows that housing prices not only positively affect the VIE of local cities, but also positively affect the VIE of neighboring cities. These findings imply the necessity of curbing the excessive rise of housing prices and decoupling public services and benefits related to homeownership. [ABSTRACT FROM AUTHOR]