Orthorhombic C3a
Mostrando 1-12 de 46 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. Estudo de obtenção da membrana cerâmica densa BaCeO3
RESUMO Nos últimos anos, pós cerâmicos à base de óxidos de estrutura do tipo perovskita ganharam atenção considerável devido às suas aplicações tecnológicas na área de membranas permeáveis de oxigênio. O óxido misto BaCeO3 apesenta-se como um material amplamente estudado em uma grande diversidade de aplicações, seja como materiais eletrolí
Matéria (Rio J.). Publicado em: 20/05/2019
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3. Dielectric and electrical properties of a mullite/glass composite from a kaolinite clay/mica-rich kaolin waste mixture
Resumo Um compósito mulita/fase vítrea foi preparado por sinterização reativa de uma mistura argila caulinítica/resíduo de caulim rico em mica com 25% em massa de resíduo. A composição de fase, microestrutura, propriedades dielétricas e elétricas do compósito sinterizado a 1400 °C foram avaliadas por difração de raios X, microscopia eletrônic
Cerâmica. Publicado em: 2019-01
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4. Influence of Pellet Compaction Pressure on the Physical Properties of La0.7Ba0.3MnO3 Manganite
Perovskite manganite La0.7Ba0.3MnO3, synthesized by ionic coordination reaction method (ICR) was compacted into pellets under different compaction pressures (Pc) and sintered at a temperature of 1150°C for 10h under a flow of O2. X-ray diffraction (XRD) data reveal that the samples can present simultaneously two phases - a rhombohedral structure with space
Mat. Res.. Publicado em: 11/12/2017
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5. Kinetics of Formation and Crystal Structure Determination of Sr4Al6O12SO4
The sulphoaluminate of strontium, Sr4Al6O12SO4, was synthesized by solid state reaction from mixture of SrCO3, Al2O3 and SrSO4 (3:3:1 molar ratio) as pellets. The kinetics of formation has been studied in the range of temperature between 850ºC and 1100ºC using quantitative X-ray powder diffraction data (XRD) analysis. Likewise, at room temperature, the cry
Mat. Res.. Publicado em: 09/02/2017
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6. Synthesis and Structural Properties of Niobium Pentoxide Powders: A Comparative Study of the Growth Process
Powders Nb2 O5 were prepared by two different synthesis method, Sol-Gel and polymeric precursors (Pechini). In the Pechini method before adding the citric acid in the process, four different solutions were used to get the samples. For Sol-gel method, two different processes were also used in obtaining powders. The precursor was completely solubilized in etha
Mat. Res.. Publicado em: 10/10/2016
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7. Crescimento e propriedades vibracionais de cristais a base de Ãxidos / Growth and Vibrational Properties of Oxide Crystals
In this work we used different experimental techniques to study four different series of inorganic oxide crystals, namely: (i) congruent lithium isotope niobate (C7LN), (ii) rare-earth doped mixed vanadates ((Nd,Yb):YxGd1-x(VO4)); (iii) alkali metal doped and pure calcium barium niobates (CaxBa1-xNb2O6); and (iv) potassium tantalite niobate (KTa1-xNbxO3). Be
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 16/03/2012
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8. Síntese, caracterização microestrutural e elétrica de compostos cerâmicos à base de soluções sólidas de titanato de estrôncio, titanato de cálcio e óxido de ferro / Synthesis, microstructural and electrical characterization of ceramic compounds based on strontium and calcium titanates and iron-oxide
CaxSr1-xTi1-yFeyO3-δ, x = 0, 0.5 and 1.0, y = 0 and 0.35, ceramic compounds were synthesized by reactive solid state synthesis of CaCO3, SrCO3, TiO2 and Fe2O3, and by the polymeric precursor technique. The ceramic powders were evaluated by thermogravimetry and differential thermal analysis, X-ray diffraction and scanning electron microscopy. Sintered c
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 19/09/2011
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9. Simulações Monte Carlo de integrais de trajetória : propriedades elásticas do 4He sólido / Path integrals Monte Carlo simulations : elastic properties of 4He
The path-integral Monte Carlo (PIMC) method is a sophisticated approach for the simulation of many-body quantum systems. In particular, it has been extensively used for the study of manybody bosonic systems such as 4He. The main objective of the present dissertation is to apply the PIMC method to determine the elastic constants of solid 4He in its hcp phase.
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 30/11/2010
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10. Cerium-doped SrHfO3 sol-gel films
SrHfO3 presents high density, which makes it interesting for host lattice when it is doped with rare earths for luminescent materials. The optical and structural studies of Ce3+-doped strontium hafnate films prepared by the sol-gel process are presented in this work. Crack-free films with waveguiding performances were obtained with heat-treatments between 40
Matéria (Rio de Janeiro). Publicado em: 2010
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11. Estudo das transiÃÃes de fase do RbBi0,31 3Nd0,02 W8/3O9, submetido a variaÃÃes de pressÃo hidrostÃtica e temperatura. / Studies of phase transitions of RbBi0,313Nd0,02W8/3O9 submit variation of hydrostatic pressure en temperature
Tungsten bronzes has attracted great attention owing to it is interesting physical properties. Hexagonal tungsten of the form AxWO3 (with A = K, Rb, Cs), are well know superconductors. The RbBi1/3W8/3O9 (RBW) material, belongs to the valence balanced hexagonal tungsten materials with ABxW3-xO9 stoichiometry (with A = Cs, K, Rb, Tl, and B = Bi, Nd, Ta, Zr, Sc
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 16/02/2009
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12. Aluminatos tricálcico cúbico e ortorrômbico : análise da hidratação in situ e produtos formados / Cubic and orthorhombic tricalcium aluminate : analysis of in situ hydration and products
A composição do clínquer controla a cinética da hidratação do cimento, devido às fases potencialmente mais reativas. O aluminato tricálcico (C3A) é a fase que reage mais rápido quando em contato com a água, formando rapidamente os aluminatos de cálcio hidratado (C3AH6, C4AH19 e C2AH8), com a liberação de elevada quantidade de calor. Para casos
Publicado em: 2008