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- 저자 : Vasilchikova, Tatyana (검색결과 1 건)
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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>
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