Crystalline Field
Mostrando 1-12 de 87 artigos, teses e dissertações.
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1. Phase transformation of kaolinite to hexagonal kalsilite using K2CO3
Abstract Hydrothermal synthesis of kalsilite was facilitated by the inclusion of potassium carbonate (K2CO3) as the source of the potassium ion. After a 24 h reaction at 220 °C, kaolin clay treated with 1.25 M K2CO3 showed the most significant peaks at 2θ of 28.5° and 34.7° by X-ray diffraction corresponding to the hexagonal kalsilite. In addition, field
Cerâmica. Publicado em: 2022
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2. IMPLEMENTAÇÃO DO CAMPO DE FORÇA CLAYFF NO GROMACS: UMA APLICAÇÃO EM ESTRUTURA DE CAULINITA
Molecular dynamics techniques are increasingly being used for material science studies, being a theoretical approach based on molecular mechanics studies. GROMACS is a free software that allows the development of simulations of various types of molecules, from biological molecules to inorganic structures associated with the area of materials, requiring the s
Quím. Nova. Publicado em: 2020-06
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3. Characterization of Nanocellulose Obtained from Cereus Forbesii (a South American cactus)
Crystalline cellulose nanofibers are obtained from the bark of Cereus Forbesii, a cactus native to the arid areas of South America. The obtaining of cellulose nanofibers was carried out in several steps: pretreatment of the raw material, elimination of hemicellulose and lignin to obtain cellulose, and an acid hydrolysis of cellulose to obtain crystalline cel
Mat. Res.. Publicado em: 20/01/2020
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4. Study of Structural and Electric Properties of the PZT 52/48 Doped With Er+3
The scientific community has shown a growing interest in relating to the ferroelectric materials and it has made an effort to develop them. Among these several ferroelectric materials, we proposed to investigated Pb(ZrTi)O3 doped with distinct Er+3 concentrations. Our aim was to investigate how the erbium affects the PZT electrical properties. To determine t
Mat. Res.. Publicado em: 25/11/2019
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5. SYNTHESIS AND THEORETICAL STUDY OF HPW CATALYSTS SUPPORTED ON NIOBIA CALCINATED AT 500 AND 600 ºC
Keggin heteropolyacids (HPW) supported on niobia have been considered for both homogeneous and heterogeneous catalysis due to its special features, like the strong Brönsted acidity, low volatility, high activity and high selectivity for various reactions in comparison with mineral acids. Literature reports many different preparation methods for these cataly
Quím. Nova. Publicado em: 26/08/2019
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6. Avaliação da eficácia de sistema de ventilação local exaustora utilizado no controle de sílica cristalina em indústria de borracha de silicone
Resumo Introdução: os sistemas de ventilação local exaustora (SVLE) podem ser utilizados para controlar a exposição ocupacional a agentes químicos. Contudo, muitas vezes são indevidamente concebidos, instalados ou operados, tornando-se ineficazes. Objetivo: avaliar a eficácia de um SVLE empregado para controle da sílica cristalina utilizada na pr
Rev. bras. saúde ocup.. Publicado em: 25/02/2019
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7. Temperature Dependence of Electrical Resistance in Ge-Sb-Te Thin Films
Nowadays, the Ge-Sb-Te system is studied extensively for use in the field of both electrical and optical non-volatile memories. The key of this application is based on the changes in the physical properties (electrical conductivity or refractive index) of these films as a result of structural transformation between amorphous and crystalline states. Both stat
Mat. Res.. Publicado em: 18/02/2019
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8. Síntesis y estudio de propiedades estructurales y magnéticas de ferritas Mg1-xZnxFe2O4 (x= 0-0,9)
ABSTRACT Nowadays, iron oxide based magnetic nanoparticles are used in several science and technology applications due to their magnetic properties. Likewise, these materials are used in biomedical applications such as contrast agents for magnetic resonance imaging, magnetic hyperthermia, targeted drug delivery, etc. In this work, the synthesis and character
Matéria (Rio J.). Publicado em: 19/07/2018
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9. Síntesis y evaluación de las propiedades magnéticas de ferritas de galio y manganeso
ABSTRACT In this work, the synthesis of MgxGa1-xFe2O4 magnetic nanoparticles (MNPs) by sol-gel method is presented. All synthesized samples were identified as a crystalline single phase and the saturation magnetization (Ms) values are within the range of 21,2 to 46,4 emu/g, while coercive field values are less than 100 Oe. The selected samples (x= 0,4 and 0,
Matéria (Rio J.). Publicado em: 19/07/2018
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10. Effect of Different Synthesis Methods on the Textural Properties of Calcium Tungstate (CaWO4) and Its Catalytic Properties in the Toluene Oxidation
Calcium tungstate (CaWO4) crystals were prepared by microwave-assisted hydrothermal (MAH) and polymeric precursor methods (PPM). These crystals were structurally characterized by X-ray diffraction (XRD), N2 adsorption, X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) measurements. The morphology and size of
Mat. Res.. Publicado em: 16/04/2018
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11. Laccase-Assisted Rapid Synthesis of Colloidal Gold Nanoparticles for the Catalytic Reduction of 4-Nitrophenol
A green method for the rapid preparation of uniform-sized colloidal gold nanoparticles under ambient conditions was presented and validated using laccase as a reduction agent in alkaline medium. UV-Vis spectrophotometry, field-emission high-resolution transmission electron microscopy, X-ray diffraction, selected area electron diffraction, energy dispersive X
J. Braz. Chem. Soc.. Publicado em: 2017-06
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12. Effect of the modification by titanium dioxide nanotubes with different structures on the fatigue response of Ti grade 2
Nanotechnology is seeing as having potential to raise benefits to several research and application areas. Recently materials with nanostructured surfaces of nanopores, nanotubes and nanowires have become an important investigation field, since their chemical and physical properties may be substantially different from those of the corresponding substrate. In
Mat. Res.. Publicado em: 18/05/2017