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Russia’s View on the International Security in Northeast Asia
Dmitry Streltsov,Anna Kireeva,Ilya Dyachkov 한국국방연구원 2018 The Korean Journal of Defense Analysis Vol.30 No.1
The article focuses on Russia’s approach to international security in Northeast Asia. It argues that Russia’s unique position is that it is not a party of any major security–political conflict, takes a neutral position on territorial conflicts as best suiting its interests of promoting cooperation with all East Asian states and objects to the involvement of third parties. Russia is involved only in a dispute with Japan where it demonstrates a flexible position. As a comparatively weak regional player, Russia is interested in maintaining peace, stability and the status quo, in particular on the Korean Peninsula, and has no revisionist agenda in East Asia. Major elements of Russia’s approach include creating an inclusive, open, transparent and equitable regional security architecture, support for polycentric regional order with Russia as one of the major centers of power, criticism of the U.S.–sponsored MBD as well as focus on a strategic partnership with China. Intensifying its Asian pivot, Moscow is increasingly concerned with the tensions on the Korean Peninsula where it promotes denuclearization, dialogue between the two Koreas, resumption of the Six–Party Talks and opposes to the dangerous actions of all parties. Russia and China advocate a “moratorium for a moratorium” proposal as the only way to mitigate tensions and create a common security mechanism.
Park, Jae-Sang,Jo, Jae Hyeon,Aniskevich, Yauhen,Bakavets, Aliaksei,Ragoisha, Genady,Streltsov, Eugene,Kim, Jongsoon,Myung, Seung-Taek American Chemical Society 2018 Chemistry of materials Vol.30 No.19
<P>Zinc-ion batteries are emerging as next-generation rechargeable batteries that can operate in aqueous electrolytes. We first examine the feasibility of open-structured VO<SUB>2</SUB>(B) as a Zn<SUP>2+</SUP> intercalation host. A bond-valence sum energy map predicts that four Zn<SUP>2+</SUP>-ion sites (Zn<SUB>C</SUB>, Zn<SUB>A1</SUB>, Zn<SUB>A2</SUB>, and Zn<SUB>C′</SUB>) can exist in the structure. Using first-principles calculations, we verified that 0.5 mol of Zn<SUP>2+</SUP> ions can be reversibly (de)intercalated with an average voltage of ∼0.61 V (vs Zn<SUP>2+</SUP>/Zn), which is comparable with the experimental results. The specific capacity of VO<SUB>2</SUB>(B) at 50 mA g<SUP>-1</SUP> is maintained up to ∼365 mAh g<SUP>-1</SUP> corresponding to the storage capacity of ∼0.57 mol of Zn<SUP>2+</SUP> ions in the framework of VO<SUB>2</SUB>(B), and its redox reaction occurs at ∼0.61 V. The high capacity is maintained for 200 cycles, with capacity retention of 80% (288 mAh g<SUP>-1</SUP>). Moreover, the capacity delivered by the VO<SUB>2</SUB>(B) electrode is stable even with cycling at a rate of 5C (1750 mA g<SUP>-1</SUP>) at approximately 110 mAh g<SUP>-1</SUP>. This high-power capability of VO<SUB>2</SUB> is supported by the theoretical approach based on first-principles calculation, which shows the activation barrier for Zn<SUP>2+</SUP> diffusion in the VO<SUB>2</SUB>(B) structure. These findings demonstrate the potential of open-structured VO<SUB>2</SUB>(B) as a new candidate material.</P> [FIG OMISSION]</BR>
Spectral and magnetic properties of Na<sub>2</sub>RuO<sub>3</sub>
Gapontsev, Vladimir V,Kurmaev, Ernst Z,Sathish, Clastin I,Yun, Seokhwan,Park, Je-Geun,Streltsov, Sergey V IOP 2017 Journal of physics, an Institute of Physics journa Vol.29 No.40
<P>We present measurements of resistivity, x-ray absorption (XAS) and emission (XES) spectroscopy together with <I>ab initio</I> band structure calculations for quasi two dimensional ruthenate Na<SUB>2</SUB>RuO<SUB>3</SUB>. Density function calculations (DFT) and XAS and XES spectra both show that Na<SUB>2</SUB>RuO<SUB>3</SUB> is a semiconductor with an activation energy of ∼80 meV. Our DFT calculations reveal large magneto-elastic coupling in Na<SUB>2</SUB>RuO<SUB>3</SUB> and predict that the ground state of Na<SUB>2</SUB>RuO<SUB>3</SUB> should be antiferromagnetic zig–zag.</P>
Nirmala, R,Jang, Kwang-Hyun,Sim, Hasung,Cho, Hwanbeom,Lee, Junghwan,Yang, Nam-Geun,Lee, Seongsu,Ibberson, R M,Kakurai, K,Matsuda, M,Cheong, S-W,Gapontsev, V V,Streltsov, S V,Park, Je-Geun Institute of Physics 2017 Journal of Physics, Condensed Matter Vol.29 No.13
<P>CuAl<SUB>2</SUB>O<SUB>4</SUB> is a normal spinel oxide having quantum spin, <I>S</I> = 1/2 for Cu<SUP>2+</SUP>. It is a rather unique feature that the Cu<SUP>2+</SUP> ions of CuAl<SUB>2</SUB>O<SUB>4</SUB> sit at a tetrahedral position, not like the usual octahedral position for many oxides. At low temperatures, it exhibits all the thermodynamic evidence of a quantum spin glass. For example, the polycrystalline CuAl<SUB>2</SUB>O<SUB>4</SUB> shows a cusp centered at ~2 K in the low-field dc magnetization data and a clear frequency dependence in the ac magnetic susceptibility while it displays logarithmic relaxation behavior in a time dependence of the magnetization. At the same time, there is a peak at ~2.3 K in the heat capacity, which shifts towards a higher temperature with magnetic fields. On the other hand, there is no evidence of new superlattice peaks in the high-resolution neutron powder diffraction data when cooled from 40 to 0.4 K. This implies that there is no long-ranged magnetic order down to 0.4 K, thus confirming a spin glass-like ground state for CuAl<SUB>2</SUB>O<SUB>4</SUB>. Interestingly, there is no sign of structural distortion either although Cu<SUP>2+</SUP> is a Jahn–Teller active ion. Thus, we claim that an orbital liquid state is the most likely ground state in CuAl<SUB>2</SUB>O<SUB>4</SUB>. Of further interest, it also exhibits a large frustration parameter, <I>f</I> = |<I>θ</I> <SUB>CW</SUB>/<I>T</I> <SUB>m</SUB>| ~ 67, one of the largest values reported for spinel oxides. Our observations suggest that CuAl<SUB>2</SUB>O<SUB>4</SUB> should be a rare example of a frustrated quantum spin glass with a good candidate for an orbital liquid state.</P>
Uma, Sitharaman,Vasilchikova, Tatyana,Sobolev, Alexey,Raganyan, Grigory,Sethi, Aanchal,Koo, Hyun-Joo,Whangbo, Myung-Hwan,Presniakov, Igor,Glazkova, Iana,Vasiliev, Alexander,Streltsov, Sergey,Zvereva, American Chemical Society 2019 Inorganic chemistry Vol.58 No.17
<P>A new oxide, sodium-iron antimonate, Na<SUB>2</SUB>FeSbO<SUB>5</SUB>, was synthesized and structurally characterized, and its static and dynamic magnetic properties were comprehensively studied both experimentally by <I>dc</I> and <I>ac</I> magnetic susceptibility, magnetization, specific heat, electron spin resonance (ESR) and Mössbauer measurements, and theoretically by density functional calculations. The resulting single-crystal structure (<I>a</I> = 15.6991(9) Å; <I>b</I> = 5.3323 (4) Å; <I>c</I> = 10.8875(6) Å; S.G. <I>Pbna</I>) consists of edge-shared SbO<SUB>6</SUB> octahedral chains, which alternate with vertex-linked, magnetically active FeO<SUB>4</SUB> tetrahedral chains. The <SUP>57</SUP>Fe Mössbauer spectra confirmed the presence of high-spin Fe<SUP>3+</SUP> (3d<SUP><I>5</I></SUP>) ions in a distorted tetrahedral oxygen coordination. The magnetic susceptibility and specific heat data show the absence of a long-range magnetic ordering in Na<SUB>2</SUB>FeSbO<SUB>5</SUB> down to 2 K, but <I>ac</I> magnetic susceptibility unambigously demonstrates spin-glass-type behavior with a unique two-step freezing at <I>T</I><SUB>f1</SUB> ≈ 80 K and <I>T</I><SUB>f2</SUB> ≈ 35 K. Magnetic hyperfine splitting of <SUP>57</SUP>Fe Mössbauer spectra was observed below <I>T</I>* ≈ 104 K (<I>T</I><SUB>f1</SUB> < <I>T</I>*). The spectra just below <I>T</I>* (<I>T</I><SUB>f1</SUB> < <I>T</I> < <I>T</I>*) exhibit a relaxation behavior caused by critical spin fluctuations, indicating the existence of short-range correlations. The stochastic model of ionic spin relaxation was used to account for the shape of the Mössbauer spectra below the freezing temperature. A complex slow dynamics is further supported by ESR data revealing two different absorption modes presumably related to ordered and disordered segments of spin chains. The data imply a spin-cluster ground state for Na<SUB>2</SUB>FeSbO<SUB>5</SUB>.</P><P>A new oxide, sodium−iron antimonate, Na<SUB>2</SUB>FeSbO<SUB>5</SUB>, was synthesized, and its structural and magnetic properties were studied. The system does not undergo a long-range magnetic order in agreement with the fact that it is a one-dimensional magnetic chain system. The mapping analysis based on density functional theory calculations shows a strong one-dimensional, antiferromagnetic intrachain exchange coupling of ∼200 K.</P> [FIG OMISSION]</BR>