Yanfeng Guo

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Metals cannot exhibit ferroelectricity because static internal electric fields are screened by conduction electrons, but in 1965, Anderson and Blount predicted the possibility of a ferroelectric metal, in which a ferroelectric-like structural transition occurs in the metallic state. Up to now, no clear example of such a material has been identified. Here we(More)
5d and 3d hybrid solid-state oxide Ca2FeOsO6 crystallizes into an ordered double-perovskite structure with a space group of P2₁/n with high-pressures and temperatures. Ca2FeOsO6 presents a long-range ferrimagnetic transition at a temperature of ~320 K (T(c)) and is not a band insulator, but is electrically insulating like the recently discovered Sr2CrOsO6(More)
In continuation of the series of perovskite oxides that includes 3d(4) cubic BaFeO3 and 4d(4) cubic BaRuO3, 5d(4) cubic BaOsO3 was synthesized by a solid-state reaction at a pressure of 17 GPa, and its crystal structure was investigated by synchrotron powder X-ray diffraction measurements. In addition, its magnetic susceptibility, electrical resistivity,(More)
The polycrystalline MO2's (HP-PdF2-type MO2, M = Rh, Os, Pt) with high-pressure PdF2 compounds were successfully synthesized under high-pressure conditions for the first time, to the best of our knowledge. The crystal structures and electromagnetic properties were studied. Previously unreported electronic properties of the polycrystalline HP-PdF2-type RuO2(More)
The crystal structure of the layered cobalt oxyfluoride Sr(2)CoO(3)F synthesized under high-pressure and high-temperature conditions has been determined from neutron powder diffraction and synchrotron powder diffraction data collected at temperatures ranging from 320 to 3 K. This material adopts the tetragonal space group I4/mmm over the measured(More)
Perovskite materials provide a large variety of interesting physical properties and applications. Here, we report on unique properties of a fully ordered magnetodielectric double-perovskite, Sc2NiMnO6 (space group P21/n, a = 4.99860 Å, b = 5.35281 Å, c = 7.34496 Å, and β = 90.7915°), exhibiting sequential magnetic transitions at T1 = 35 K and T2 = 17 K. The(More)
Crystals of the newly synthesized compound Ca(3)LiOsO(6) were grown by a flux method using LiCl and KCl, followed by single-crystal X-ray diffraction (XRD), low-temperature powder XRD, and measurements of ac and dc magnetic susceptibility and specific heat. The data indicate that Ca(3)LiOsO(6) has a fully opened electronic gap with an antiferromagnetic(More)
The antiperovskite Mn(3)ZnN is studied by neutron diffraction at temperatures between 50 and 295 K. Mn(3)ZnN crystallizes to form a cubic structure at room temperature (C1 phase). Upon cooling, another cubic structure (C2 phase) appears at around 177 K. Interestingly, the C2 phase disappears below 140 K. The maximum mass concentration of the C2 phase is(More)
Data mining for data stream becomes important in academic areas. Due to large-scale data, people utilize incremental learning approach to handle the data. In this paper, a modified Support Vector Machine (SVM) incremental learning model is proposed. Through experiments of selecting kernel function for the SVM method, we optimize several parameters. Real(More)