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[en] Complete text of publication follows. 1-D global inversions of observatory and satellite data reveal radial conductivity profiles in the Earth's mantle. Traditionally, these have been interpreted as average values at given depth. However, the predominant P10 geometry of the magnetospheric ring current, and the P21 local-time related geometry of the ionospheric currents represent strong biases in 1-D interpretation of responses of fully 3-D heterogeneous Earth. We present a series of synthetic checks, applying 1-D time-domain inversion technique on 3-D simulated data for conductivity models ranging from simple configurations based on low-degree spherical harmonics to complicated structures derived from temperature, chemical and phase composition based on geodynamical modelling. We show that it is the presence or lack of lateral interconnection of highly conductive phases in the direction of prevailing external currents that determines the results of 1-D inversion. In particular, this effect can explain the recently shown invisibility of highly conductive postperovskite in the D'' layer to induction studies excited by strong transient signals - the geomagnetic storms.
[en] Inorganic lead halide perovskite nanocrystals (NCs) with superior photoelectric properties are expected to have excellent performance in many fields. However, the anion exchange changes their features and is unfavorable for their applications in many fields. Hence, impeding anion exchange is important for improving the composition stability of inorganic lead halide perovskite NCs. Herein, CsPbX 3 (X = Cl, Br) NCs are coated with Cs4PbX 6 shell to impede anion exchange and reduce anion mobility. The Cs4PbX 6 shell is facily fabricated on CsPbX 3 NCs through high temperature injection method. Anion exchange experiments demonstrate that the Cs4PbX 6 shell completely encapsulates CsPbX 3 NCs and greatly improves the composition stability of CsPbX 3 NCs. Moreover, our work also sheds light on the potential design approaches of various heterostructures to expand the application of CsPbM3 (M = Cl, Br, I) NCs. (paper)
[en] The bond-valence sum approach to spontaneous valence polarization in perovskite-like nanocrystallites ABO3 is presented. As the bond-valence method allows estimating the amount of valence charge distributed within the given bond according to bond length, the microscopic polarization in the ABO3 structure may be directly derived from the valence deviation in two conjunctive bonding spheres A-O12 and B-O6. The concept was demonstrated on examples and a comparable agreement with data taken either from experiments or first principle calculation was seen. The bond-valence polarization appeared as one of the possible sources contributing to the final macroscopic polarization of the bulk materials.
[en] Atomistic simulations show that there are long-ranged ferroelectric interactions between the ferroelectric layers in ferroelectric/paraelectric superlattices mediated by continuous chains of polarization running through the intervening paraelectric layers. The resulting behavior of the superlattice is strongly dependent on the modulation length. At short modulation lengths the superlattice acts as a single-component system; at long modulation lengths the individual ferroelectric layers act almost independently
[en] In this work, a high performance vertical-type photodetector based on two-dimensional (2D) CH3NH3PbI3 perovskite nanosheets was fabricated. The low trap density of the perovskite nanosheets and their short carrier diffusion distance result in a significant performance enhancement of the perovskite-based photodetector. The photoresponsivity of this vertical-type photodetector is as high as 36 mA W−1 at visible wavelength, which is much better than traditional perovskite photodetectors (0.34 mA W−1). Compared with traditional planar-type perovskite-based photodetectors, this vertical-type photodetector also shows the advantages of low-voltage operation and large responsivity. These results may pave the way for exploiting high performance perovskite-based photodetectors with an ingenious device design. (paper)
[en] Reports the main dosimetric properties of a new Perovskite LiMgF3 doped by Ce, E r and Dy impurities. Sensitivity, T L dose response, fading and t raping parameters are some of the properties carried out
[en] We use high-pressure Raman-scattering spectroscopy to study LaFeO3 synthesized by using the sol-gel method. The structural evolution of the samples under high pressure and at room temperature is monitored via the Raman-scattering spectrum in the pressure range of 0.50 to 22.1 GPa. When the pressure surpasses 12 GPa, the Raman spectra change significantly around 180 cm−1, which indicates a structural phase transition. However, the Raman spectrum remains constant under 5.0 GPa, which indicates that the LaFeO3 structure is preserved at these pressures. (paper)
[en] In our paper, we reported a previously unobserved Raman-like band centered at around 550 cm-1 and found that it diminished after the material degraded. This erratatum provides a more accurate interpretation; the wrong interpretation does not affect the primary conclusion.
[en] In a combined theoretical and experimental work, we investigate X-ray absorption near-edge structure spectroscopy of the I L3 and the Pb M5 edges of the methylammonium lead iodide (MAPbI3) hybrid inorganic-organic perovskite and its binary phase PbI2. The absorption onsets are dominated by bound excitons with sizable binding energies of a few hundred millielectronvolts and pronounced anisotropy. The spectra of both materials exhibit remarkable similarities, suggesting that the fingerprints of core excitations in MAPbI3 are essentially given by its inorganic component, with negligible influence from the organic groups. Furthermore, the theoretical analysis complementing experimental observations provides the conceptual insights required for a full characterization of this complex material.