13870-10-5Relevant academic research and scientific papers
Crystal structure, physical properties, and electronic and magnetic structure of the spin S = 5/2 zigzag chain compound Bi2Fe(SeO3)2OCl3
Berdonosov, Peter S.,Kuznetsova, Elena S.,Dolgikh, Valery A.,Sobolev, Alexei V.,Presniakov, Igor A.,Olenev, Andrei V.,Rahaman, Badiur,Saha-Dasgupta, Tanusri,Zakharov, Konstantin V.,Zvereva, Elena A.,Volkova, Olga S.,Vasiliev, Alexander N.
, p. 5830 - 5838 (2014)
We report the synthesis and characterization of the new bismuth iron selenite oxochloride Bi2Fe(SeO3)2OCl 3. The main feature of its crystal structure is the presence of a reasonably isolated set of spin S = 5/2 zigzag chains of corner-sharing FeO6 octahedra decorated with BiO4Cl 3, BiO3Cl3, and SeO3 groups. When the temperature is lowered, the magnetization passes through a broad maximum at Tmax ≈ 130 K, which indicates the formation of a magnetic short-range correlation regime. The same behavior is demonstrated by the integral electron spin resonance intensity. The absorption is characterized by the isotropic effective factor g ≈ 2 typical for high-spin Fe3+ ions. The broadening of ESR absorption lines at low temperatures with the critical exponent β = 7/4 is consistent with the divergence of the temperature-dependent correlation length expected for the quasi-one-dimensional antiferromagnetic spin chain upon approaching the long-range ordering transition from above. At TN = 13 K, Bi 2Fe(SeO3)2OCl3 exhibits a transition into an antiferromagnetically ordered state, evidenced in the magnetization, specific heat, and Moessbauer spectra. At T N, the 57Fe Moessbauer spectra reveal a low saturated value of the hyperfine field Hhf ≈ 44 T, which indicates a quantum spin reduction of spin-only magnetic moment δS/S ≈ 20%. The determination of exchange interaction parameters using first-principles calculations validates the quasi-one-dimensional nature of magnetism in this compound.
Process for the production of urethanes
-
, (2008/06/13)
This invention relates to an improved process for the production of urethanes (i.e. carbamic acid esters) by reacting organic nitro compounds with carbon monoxide and organic compounds containing at least one hydroxy group in the presence of a unique catalyst system. The catalyst system consists of palladium or a palladium compound and iron oxychloride or a mixture of iron compounds containing iron oxychloride.
