Revealing a masked Verwey transition in nanoparticles of coexisting Fe-oxide phases

We provide direct evidence of a Verwey transition in a nanoparticle ensemble of mixed iron-oxide phases via temperature-dependent Raman spectroscopy.

COMPUTER QUANTUM-CHEMICAL SIMULATION OF MULTICOMPONENT SIO-MEO SYSTEMS

Впервые с помощью компьютерного квантово-химического моделирования показана возможность формирования поликомпонентных систем SiO - FeO, SiO -MnO и SiO - CuO путем адсорбции на поверхности микросфер SiO металлоксидного слоя, состоящего из наночастиц диоксида марганца (IV), смешанного оксида железа или наночастиц оксида меди (II). По результатам сканирующей электронной микроскопии установлено, что формирование металлоксидного слоя в образце SiO - FeO произошло наиболее равномерно среди всех представленных образцов поликомпонентных систем. В рамках квантовохимического моделирования установлено, что наиболее энергетически выгодным и стабильным является взаимодействие SiO с наночастицами FeO . For the first time, in this work, the possibility of forming multicomponent SiO -FeO, SiO -MnO and SiO - CuO systems by adsorption of a metal oxide layer consisting of nanoparticles of manganese (IV) dioxide, mixed iron oxide or nanoparticles of copper (II) oxide on the surface of SiO microspheres has been shown by means of a computer quantum-chemical simulation. According to the results of the scanning electron microscopy, it was found that formation of a metal oxide layer in the SiO - FeO sample occurred most uniformly among all the presented samples of multicomponent systems. Within the framework of quantum-chemical simulation, it was found that the most energetically favorable and stable was the interaction of SiO with FeO nanoparticles.

Iron oxide decorated N-doped carbon derived from poly(ferrocene-urethane) interconnects for the oxygen reduction reaction

We report the synthesis of mixed iron oxide particles decorated on nitrogen-doped carbon by forming covalent polyurethane linkages between ferrocene and phloroglucinol.

The Value of Influence of Vibrations of the Chemical Composition of Technogenic Waste on Properties of Pigments

Influence of possible fluctuations of a chemical composition of waste of galvanic productions on the mixed iron oxide pigment (MIP) main pigmentary properties is established. It is shown that introduction of samples of MIP with the raised content of these or those metals in such industrial paintwork materials as alkyd PF-115 enamel and a primer GF-021, practically doesn't change physic-mechanical properties and firmness of the coverings received on their basis. It allows to apply slimes of galvanic productions as the main raw materials by industrial production of MIP and to reduce prime cost of a pigment by 15-20%.

Optical and Structural Changes of Fe Implanted Sapphire

Single crystalline colorless α-Al2O3 samples were implanted with several fluences of Fe+ ions in the range of 1×1016 to 5×1017 Fe+ cm-2 at room temperature. Optical absorption and luminescence measurements were carried out before and after annealing in reducing and oxidizing atmospheres. The structural changes were studied with RBS/channeling and x-ray diffraction. After implantation, the damage induces a brownish coloration in the samples for fluences below 2×1017 Fe+ cm-2. The optical spectra are characterized by an absorption band centered at 200 nm. This band is strongly reduced after annealing at 1100 °C in reducing atmosphere and a new well-defined band develops around 350 nm. This new band shifts to lower values with the implanted fluence, which is an indication of its correlation with the dimensions of the iron precipitates formed in the implanted region. The existence of these precipitates was confirmed by x-ray diffraction and TEM. The samples implanted with fluences above 1×1016 Fe+ cm-2 annealed in oxidizing atmosphere display different optical absorption spectra, with respect to those annealed in reducing atmosphere, characterized by an increase in the intensity of the peak at 200 nm. Luminescence measurements show the presence of F and F+ centers in the samples. The existence of these defects can be explained by the need of charge compensation and strain release due to the formation of mixed iron oxide or metallic precipitates.