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With the development of consumer electronic devices and electric vehicles, lithium-ion batteries (LIBs) are vital components for high energy storage with great impact on our modern life. However, LIBs still cannot meet all the essential demands of rapidly growing new industries. In pursuance of higher energy requirement, metal batteries (MBs) are the next-generation high-energy-density devices. Li/Na metals are considered as an ideal anode for high-energy batteries due to extremely high theoretical specific capacity (3860 and 1165 mAh g-1 for Li and Na, respectively) and low electrochemical potential (-3.04 V for Li and -2.71 V for Na vs. standard hydrogen electrode). Unfortunately, uncontrolled dendrite growth, high reactivity, and infinite volume change induce severe safety concerns and poor cycle efficiency during their application. Consequently, MBs are far from commercialization stage. This Review represents a comprehensive overview of failure mechanism of lithium/sodium metal anode and its progress for rechargeable batteries through (i) electrolyte optimization, (ii) artificial solid-electrolyte interphase (SEI) layer formation, and (iii) nanoengineering at materials level in current collector, anode, and host. The challenges in current MBs research and potential applications of lithium/sodium metal anodes are also outlined and summarized.

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We investigated implications of nanostructure formation on structural and magnetotransport properties of La0.7Sr0.3MnO3 compound. The polycrystalline nanomaterials of variable grain sizes were synthesized by using sol-gel method. The structural parameters obtained by Rietveld refinement of the X-ray diffraction data indicated that the samples possess perovskite structure with orthorhombic Pnma symmetry. The X-ray Photoemission Spectra showed chemical shift in the lowest particle size sample due to oxygen deficiency. The average particle size observed through transmission electron microscopy varied from 22 nm to 34 nm. The particle size induced metal-insulator transition and substantial increase in electrical resistivity observed in these nanomaterials are in contrast with the bulk material phase diagram. We also observed temperature and magnetic field dependent colossal magnetoresistance. The low-field magnetoresistance is substantially enhanced in nanomaterials samples, making it more promising for device applications. A divergence in field cooled and zero field cooled magnetization indicated possibility of magnetic spin-glass behavior.

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We have investigated the nanoscale switching properties of strain-engineered BiFeO(3) thin films deposited on LaAlO(3) substrates using a combination of scanning probe techniques. Polarized Raman spectral analysis indicates that the nearly tetragonal films have monoclinic (Cc) rather than P4mm tetragonal symmetry. Through local switching-spectroscopy measurements and piezoresponse force microscopy, we provide clear evidence of ferroelectric switching of the tetragonal phase, but the polarization direction, and therefore its switching, deviates strongly from the expected (001) tetragonal axis. We also demonstrate a large and reversible, electrically driven structural phase transition from the tetragonal to the rhombohedral polymorph in this material, which is promising for a plethora of applications.