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Structural and Magnetic Properties of Monophasic Maghemite (γ-Fe2O3) Nanocrystalline Powder

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Advances in Nanoparticles 2014年第3期3卷 114-121页

作者： Juan Adrián Ramos Guivar Arturo Isaías Martínez Ana Osorio Anaya Luis De Los Santos Valladares Lizbet León Félix angel bustamante dominguez Cavendish Laboratory Department of Physics University of Cambridge Cambridge UK Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional Cinvestav Unidad Saltillo Ciudad de México México Ciudad de México México Laboratorio de Cerámicos y Nanomateriales Facultad de Ciencias Físicas Universidad Nacional Mayor de San Marcos Lima Perú Laboratorio de Nanotecnología e Innovación Tecnológica Departamento de Química e Ingeniería Química Universidad Nacional Mayor de San Marcos Lima Perú Núcleo de Física Aplicada Instituto de Física Universidade de Brasília Brasília Brasil

Structural and magnetic studies of monophasic maghemite (γ-Fe2O3) magnetic nanocrystallites (MNCs) synthesized by the co-precipitation chemical route are reported in this paper. For the synthesis, a starting precursor of magnetite (Fe3O4) in basic medium was oxidized at room temperature by adjusting the pH = 3.5 at 80°C in an acidic medium without surfactants. X-ray diffraction (XRD) pattern shows widened peaks indicating nanometric size and Rietveld Refinement confirms only one single-phase assigned to γ-Fe2O3 MNCs. High Resolution Transmission Electron Microscopy (HR-TEM) demonstrates the formation of nanoparticles with diameter around D ≈ 6.8 ± 0.1 nm which is in good agreement with Rietveld Refinement (6.4 ± 1 nm). A selected area electron diffraction pattern was carried out to complement the study of the crystalline structure of the γ-Fe2O3 MNCs. M(H) measurements taken at different temperatures show almost zero coercivity and remanence indicating superparamagnetic domain and high magnetic saturation.

关键词： Monophasic Nanomaghemite Rietveld Refinement TEM SAED M-H Loops ZFC

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Physical and chemical characterization of sediments from an Andean river exposed to mining and agricultural activities: The Moquegua River, Peru

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International Journal of Sediment Research 2022年第6期37卷 780-793页

作者： Luis de Los Santos Valladares Juan Luis Ccamapaza Renato Arturo Valencia-Bedregal Luis Enrique Borja-Castro Jose Velazquez-Garcia Dehiwalage Harshani Nimalika Perera Adrian Ionescu David Arvidsson Eustace Peregrine Barnes Peter Newton Hugo Lepage Patrick Byrne angel Guillermo bustamante dominguez Crispin H.W.Barnes Cavendish Laboratory Department of Physics University of Cambridge Escuela Acad emico Profesional de Ingeniería Ambiental Universidad Nacional de Moquegua Provincia de Mariscal Nieto Laboratorio de Cer amicos y Nanomateriales Facultad de Ciencias Físicas Universidad Nacional Mayor de San Marcos School of Biological and Environmental Science Liverpool John Moores University

This study presents an analysis of sediments in an Andean river impacted by both natural conditions and anthropogenic activities. Fifty samples were collected from selected sites throughout the Moquegua River drainage basin, and Tambo River headwaters at Pasto Grande, in Peru, and analysed with X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy and thermogravimetric analysis. Si, Ca, Al, Fe, and O, common constituents of soils, were dominant, along with K, N, and P. The latter originating as primary macronutrients or chemical residuals from fertilizers used in agriculture. Higher concentrations of macronutrients and organic components were found in agricultural and urban areas, respectively. Arsenic minerals were also detected, which occur naturally, but possibly at levels augmented by anthropogenic activity. The application of cluster analysis revealed clustering between arsenic, arsenolite, and potassium but no significant geospatial correlation between sample sites in the drainage basin.

关键词： Andean river Moquegua river Sediments Fourier-transform infrared spectroscopy TG-DTG/DTA Clustering analysis

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Chemical Solution Deposition of YBa2Cu3O7 Films on YSZ （100） Substrates

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Journal of Chemistry and Chemical Engineering 2014年第6期8卷 547-551页

作者： Henry Elías Sanchez Comejo angel bustamante dominguez1 Ana María Osorio Luis De Los Santos Valladares José Albino Aguiar Crispin H. W. Barnes Ceramics and Nanomaterials Laboratory Department of Physics Major National University of San Marcos Lima 14-0149 Peru Department of Chemistry and Chemical Engineering Major National University of San Marcos Lima 14-0149 Peru Superconductivity and Advanced Materials Laboratory Department of Physics Federal University of Pernambuco Recife50670-901 Brazil Cavendish Laboratory Department of Physics University of Cambridge Cambridge CB3 0HE United Kingdom

We report the epitaxial growth of YBCO (YBa 2 Cu 3 O 7 ) films on YSZ (Yttria-stabilized Zirconia) (100) substrates by chemical solution deposition. The precursor solution was prepared by dissolving stoichiometric amounts of acetates of Y(OOCCH 3 ) 3 ·4H 2 O, Ba(OOCCH 3 ) 2 and Cu(OOCCH 3 )·2H 2 O in an aqueous solution of oxalic acid (H 2 C 2 O 4 ) and following the sol-gel route. This solution was directly dripped onto YSZ (100) substrates with the help of a Fisher pipette. To form the YBCO film, the sample was crystallized by annealing at 860 °C for 12 h in an oxidizing atmosphere. The characterization was performed by XRD (X-ray diffraction) analysis which revealed high intensity (001) reflections and denoted that most of the grains were c-axis oriented. Randomly oriented grains and other phases such as Y 2 BaCuO 5 and CuO were also detected. The superconducting YBCO phase is demonstrated from the susceptibility versus temperature measurements which indicate a superconducting critical temperature ≈ 90 K. In addition, a surface morphology analysis was performed by optical microscopy and atomic force microscopy which revealed an average roughness of 0.2197 μm.

关键词： YBa2Cu3O7 化学溶液沉积 YBCO薄膜 YSZ 氧化钇稳定的氧化锆超导临界温度原子力显微镜 X射线衍射

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The role of power-to-gas in the European Union

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Green Chemical Engineering 2020年第1期1卷 6-8页

作者： Antonio dominguez-Ramos angel Irabien Department of Chemical and Biomolecular Engineering Avda.Los CastrosSnETSIIyTSantander39005Sp

The primary energy panorama in the European Union is still dominated by a significant share of fossil fuels in the form of coal,natural gas and oil.As a result,an ecological transition is encouraged in order to curb the related CO_(2)emissions from fossil fuels thus providing an alignment with the Paris Agreement.In the light of a renewable dominated future in the EU,Power-to-Gas technologies can play a major role not only to curb the current CO_(2)emissions but add extra flexibility to the power network.Great challenges remain ahead,due to the difficulties to couple all the elements needed in such a complex value chain,from technical to financial.

关键词： alignment power emissions

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Genetic Stability of Cryopreserved Grapevine （Wtis vinifera L.） Genome by Vitrification Method

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Journal of Agricultural Science and Technology(B) 2016年第6期6卷 380-386页

作者： Maria Femanda Lazo Javalera Martin Ernesto Tiznado Hemandez Irasema Vargas Arispuro Miguel angel Martinez Tellez Maria Auxiliadora Islas Osuna Miguel angel Hemandez Ofiate Marisela Rivera dominguez Food Science Coordination Research Center for Food and Development Hermosillo Sonora 83000 Mexico Food Technology of Plant Origin Coordination Research Center for Food and Development Hermosillo Sonora 83000 Mexico

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