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• Nb5+-doped γ - Fe 2 O 3 were synthesized by sol–gel method. • As the Nb doping increases (≥3.8 at.%), the transformation from γ - Fe 2 O 3 to α-Fe 2 O 3 was suppressed up to 600 °C. • At elevated temperature of 700 °C, γ - Fe 2 O 3 went through full transformation to α-Fe 2 O 3 by expelling large amount of Nb to the surface of α-Fe 2 O 3 forming FeNbO 4. Nb5+-doped γ - Fe 2 O 3 was synthesized by sol–gel method followed by calcination at various temperatures from 200 to 700 °C, analyzed using Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS) and Mössbauer Spectroscopy. PXRD results show the formation of γ - Fe 2 O 3 at 300 °C and it begins to transform to α-Fe 2 O 3 at 350 °C for pure and 2 at.% Nb-doped samples. As the Nb doping increases (≥3.8 at.%), the transformation was suppressed up to 600 °C. TEM EDS confirms the incorporation of Nb to γ - Fe 2 O 3 lattice in 9.1 at.% Nb sample calcined at 500 °C. At elevated temperature of 700 °C, γ - Fe 2 O 3 went through full transformation to α-Fe 2 O 3 by expelling large amount of Nb to the surface forming FeNbO 4. TEM EDS confirms the compositional change during this process with reduced Nb content in α-Fe 2 O 3 and Nb-rich nanoparticle on the surface of α-Fe 2 O 3. Superparamagnetic properties were observed for Mössbauer spectra when the Nb doping increased, which is caused by decreased particle size. The slight increase in internal magnetic field also indicated the transformation from γ - Fe 2 O 3 to α-Fe 2 O 3. High Nb doping with 20 and 40 at.% shows the formation of FeNbO 4 at lower temperature where limited or almost no Nb substitution in α-Fe 2 O 3 was detected by EDS. [ABSTRACT FROM AUTHOR]

Mixed-valence state of binuclear metallocene derivatives and spin-crossover (SCO) phenomena of the assembled Fe(II) complexes have been studied by using Mössbauer spectroscopy. The understanding of the results obtained by Mössbauer spectra is well supported by means of X-ray structural analysis and density functional theory (DFT) calculation. Benchmark study of relativisitic DFT calculation by using Mössbauer isomer shifts of Eu, Np complexes reveals the validity of the calculation. Such study sheds light on the bonding character of 4f and 5f electron. These results are reviewed. [ABSTRACT FROM AUTHOR]

One of the four neighboring fields tended to show slightly higher contamination of radioactive cesium in rice grain soon after Fukushima Daiichi Nuclear Power Plant accident. In order to understand the reason, the oxidative/reductive atmosphere in the paddy field was investigated using 57Fe Mӧssbauer spectroscopy. The iron concentration variation was also investigated based on soil size distribution. It was suggested that the oxidative/reductive condition of iron state may reflect the features of the soils and then affect the solubility of potassium and radioactive cesium in the field. Oxidative atmosphere and in particular more abundant iron in larger size soil may affect the transfer of radioactive cesium from soil to rice grain. [ABSTRACT FROM AUTHOR]

The article discusses the synthesis of iodine-bridged iodo(pentamethylcyclopentadienyl)iron dicarbonyl complex. The study used single crystal X-ray diffraction, infrared spectroscopy and iron Mössbauer spectroscopy to characterize the crystal structure and electronic state of the complex. It was discovered that iodine-bridged complex affected the CO ligand bond via iron atom.

[Display omitted] • Heterojunction structure of Nb-doped α-Fe 2 O 3 and FeNbO 4 was obtained. • This heterojunction sample showed a good catalytic activity for Photo-Fenton reaction to decompose methylene blue. • The catalyst can be collected using magnet due to ferrimagnetic interaction. Photocatalytic activity of α-Fe 2 O 3 under visible light had been studied intensively. Rapid electron-hole recombination is the main drawback of α-Fe 2 O 3 and the photocatalytic activity can be enhanced by transition metal doping and heterojunction structure. In the present study, α-Fe 2 O 3 doped with various amounts of Nb were synthesized using a simple sol–gel method, and further characterization and catalytic activity were investigated. PXRD, TEM-EDS and Mössbauer measurement showed the formation of weak-ferromagnetic Nb-doped α-Fe 2 O 3 and FeNbO 4 , where heterojunction structure was suggested. UV–vis spectrum showed a broad absorption in visible-light regions with a narrow band gap between 2.27 and 2.97 eV. Photo-Fenton reaction using α-Fe 2 O 3 to decompose methylene blue (MB) was conducted to evaluate the catalytic activity. Nb-doped sample showed a significant improvement compared with pure α-Fe 2 O 3. PXRD and Mössbauer spectroscopy revealed the α-Fe 2 O 3 and FeNbO 4 phases, which were attached to a magnet due to the ferrimagentic character of Nb-doped α-Fe 2 O 3. The high catalytic activity with k value 7.1 * 10−2/min was obtained for 7.4Nb600. Higher catalytic activity was also observed for 20Nb600 and 40Nb600, which were driven by higher surface area, Nb substitution and heterojunction structure. Mechanistic analysis revealed that the primary reaction of MB decomposition is the Photo-Fenton process. [ABSTRACT FROM AUTHOR]

Abstract: Assembled iron complex Fe(NCS)2(bpp)2·2(benzene) (bpp=1,3-bis(4-pyridyl)propane), enclathrating benzene molecules, has been synthesized and its host framework was 1D chain structure. By releasing benzene molecules, the host framework changed to 2D interpenetrated structure. The desorbed complex enclathrated benzene molecules again and the host framework returned to 1D structure. Although the spin state remained in the high spin upon the desorption and adsorption of the benzene molecules, 57Fe Mössbauer spectra revealed that the symmetry around iron atom changed depending on the sorption. The reversible structural change of host framework was tried to explain by two factors: the crystal stability by making up the interstitial space and the conformer stability in coordinated bridging ligand bpp. [Copyright &y& Elsevier]