Microstructural evolution of mullites produced from single-phase gels

The crystalline microstructure of mullites obtained by heating monophasic gels has been investigated. Gels with alumina to silica molar ratio of 3:2 (as in secondary mullite) and 2:1 (as in primary mullite) were prepared by gelling mixtures of aluminium nitrate and tetraethylorthosilicate. Phase transformations were induced by heating the gel precursors, with different final treatment temperatures between 1173 and 1873 K. The mullites formed as a result of thermal treatment were studied by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The crystalline structure (unit-cell parameters) and microstructure were determined from X-ray diffraction pa…

Study of Synthesis Methods to Obtain the Ceramic Pigment Pink Coral, Fe-ZrSiO<sub>4</sub>

X-ray diffraction microstructure analysis of mullite, quartz and corundum in porcelain insulators

Abstract The X-ray diffraction microstructure analysis has been performed on commercial samples of the silica and alumina porcelain insulators obtained at 1300 °C, with the same time of firing. The study was carried out on mullite, corundum and quartz by applying several integral breadth methods (i.e. the Williamson–Hall analysis, the Langford method and the Halder–Wagner approximation) and the Fourier analysis (Warren–Averbach method). The apparent crystallite sizes determined for the mullite are direction-dependent (anisotropic) and within each group of samples, on average, the greatest values are obtained along the direction [0 0 1]. With regard to the microstructure of the corundum and …

Automated Calculation Method to Determine the Output Power Based on the Frequency for Induction Heating IGBT Parallel Inverter

The fact that some inverter topologies used in induction heating applications allow the soft switching working operation lets the progressive replacement of the MOSFET with the IGBT in high power inverters. This is due to two main reasons, the former is the IGBT reliability and the latter is the ratio defined as the price of the component per output power. In this article an automated method to determine the output power based on the frequency of an inverter build with different IGBT is described. To carry out this method is necessary to define the power cycle and to develop the calculation process which determines the energy losses in the working conditions of the resonant parallel inverte…

Quantitative X-ray diffraction phase analysis of airborne particulate collected by a cascade impactor sampler using the Rietveld full-pattern fitting method

Samples of airborne particulate were collected at the “El Ingenio” site in Castellón (Spain) using a cascade impactor sampler. Quantitative analysis of present phases in the aerosol was performed using the full-pattern fitting Rietveld method. Quantitative information was obtained from refined individual scale factors and unit-cell volumes, obtained with a Rietveld refinement program. Quartz, calcite, and gypsum were encountered as major phases, and their size distribution and concentration in the atmosphere were calculated.

Optimized Topology for High Efficiency Battery Discharge Regulator

In the following years power levels of 20 kW to 50 kW will be demanded by the telecommunication satellites. It is not possible to keep 0.5 kW modules with up to 100 modules in parallel and, therefore, higher power modules must be used. A higher bus voltage seems also necessary and any voltage below 150 V and above 100 V could meet the needs. In addition, new optimized topologies that process only a part of the total power delivery can be employed to improve the efficiency. In this article, design guidelines and experimental results of a high efficiency battery discharge regulator (BDR) module based on parallel power processing are given.

Quantitative X-Ray Powder Diffraction Analysis of Some Feldspars Used as Raw Material in Ceramics

Bidirectional High-Efficiency Nonisolated Step-Up Battery Regulator

The design and results of a high-efficiency high-power (5 kW) nonisolated bidirectional dc-dc converter is presented. High stability due to minimum phase behavior is an additional benefit of the topology. The converter is a new boost with output filter where input and output inductors are coupled. This converter is useful with any system that needs to charge and discharge backup batteries and can be applied in space, automotive, and telecom power systems.

Copper(II) complexes with the N,N,O-tridentate ligand 6-amino-5-formyl-1,3-dimethyluracilato-(N6)-benzoylhydrazone: synthesis, spectral and XRD studies

Abstract From reactions between different Cu(II) salts and the Schiff base 6-amino-5-formyl-1,3-dimethyluracil-benzoylhydrazone (H2BEZDO) in alcohol, six new copper complexes with simplified formulas [Cu(HBEZDO)(H2O)(MeOH)]NO3 (1), [CuCl(HBEZDO)(DMF)] (2), [CuBr(HBEZDO)]·2H2O (3), CuBr(HBEZDO) (4), Cu(ClO4)(HBEZDO)·H2O (5), and Cu(SO4)1/2(HBEZDO)·1 1 2 H2O (6) were isolated. The structures of compounds 1, 2 and 3 have been established by means of XRD diffraction methods. In the three compounds, the Schiff base acts as a tridentate monodeprotonated ligand through the N(6), N(51) and O(52) atoms, making two five- and six-membered chelate rings. In the structure of 1 and 2, the solvent molecul…

X-ray powder diffraction phase analysis and thermomechanical properties of silica and alumina porcelains

Chemical and mineralogical characterization, using the Rietveld method, of some silica and alumina rich porcelains and its relationship with thermomechanical properties have been studied in this work. X-ray powder diffraction analysis allows to differ clearly between silica and alumina porcelains. X-ray study shows that both porcelains have a content of vitreous phase. This vitreous phase is higher in the silica than in the alumina porcelain. Dilatometric studies combined with powder diffraction methods shows a strong relationship between silica content and a lower expansion coefficients and between alumina content and a higher crash resistance. Lower contents in vitreous phase in porcelain…

A rietveld study of the cation substitution between uvarovite and yttrium-aluminum synthetic garnets, obtained by sol-gel method

A series of synthetic garnets solid solutions with compositions between Y 3 Al 2 Al 3 O 12 (Y-Al garnet) (YAG) and Ca 3 Cr 2 Si 3 O 12 (uvarovite) was synthesized using the sol-gel method. The expected general formula is (Ca x Y 1-x ) 3 (Cr x Al 1-x ) 2 (Si x Al 1-x ) 3 O 12 where x=0 to x=1. The cation distribution in dodecahedral, octahedral and tetrahedral sites and bond distances in these synthetic garnets were determined using the Rietveld method. It shows the incomplete substitution in small sites. The smaller site the smaller substitution there is

Quantitative Phase Analysis of Mixtures of Three Components using Rietveld and Rius Standardless Methods. Comparative Results

Eight samples, supplied by the Commission on Powder Diffraction of the International Union of Crystallography, through the Round Robin on quantitative phase analysis, were analized using standardless methods. Samples were mixtures of corundum, zincite and fluorite in different ratios. The Rietveld method, using the DBW 3.2 and FULLPROF software, and the Rius method, using MENGE-PC software, were used. Results obtained agree well with the real composition supplied (a posteriori) by the IUCr.

Synthesis and spectral studies on metal complexes with the neutral O,N,O-tridentate Schiff base 6-amino-5-formyl-1,3-dimethyluracil-benzoylhydrazone

Abstract From the reaction between different Co(II), Cu(II), Zn(II) and Pd(II) salts and the Schiff base 6-amino-5-formyl-1,3-dimethyluracil-benzoylhydrazone (H 2 BEZDO), in ethanol and acetone media, five complexes with M/L stoichiometry 1/1, containing the neutral organic ligand, have been obtained. These compounds have been studied by IR, 13 C and 1 H-NMR, UV-VIS-NIR and EPR spectroscopies and magnetic measurements. A single crystal X-ray diffraction study has been carried out on the compound [Cu(ClO 4 )(H 2 BEZDO)(H 2 O)]ClO 4 . The structure consists of mononuclear cations [Cu(ClO 4 )(H 2 BEZDO)(H 2 O)] + and uncoordinated perchlorate anions. The coordination environment around the Cu(…

An X-ray powder diffraction study of the microstructural evolution on heating 3:2 and 2:1 mullite single-phase gels

Single-phase gels with compositions 3Al2O3·2SiO2 and 2Al2O3·SiO2 were prepared by gelling mixtures of aluminium nitrate and tetraethylorthosilicate. Gels were fast heated at different temperatures between 900°C and 1600°C. The phase transformation and microstructural changes of both mullite precursor gels over the temperature range were followed by X-ray powder diffraction (XRD), lattice parameter determination (LP), and scanning and transmission electron microscopies (SEM and TEM). The distribution of crystallite sizes and strains were determined by linewidth refinements of X-ray diffraction patterns using the integral breadth method of Langford and the Warren-Averbach analysis. XRD of bot…

Caracterización mineralógica de materias primas cerámicas por métodos cuantitativos de difracción de rayos x

[ES] El objetivo de este trabajo es la caracterización de fases minerales presentes en materias primas utilizadas en la industria cerámica. Para ello se utilizan dos métodos cuantitativos basados en la difracción de rayos X, el método de Rietveld y un método sin estándar. Los resultados obtenidos por difracción rayos X de estos materiales policristalinos se comparan con los correspondientes análisis químicos y la composición normativa calculada. La precisión y reproducibilidad de los resultados obtenidos, en concordancia con los del análisis químico, son una de las más importantes ventajas de la difractometría cuantitativa que facilitan su utilización en la industria cerámica en el control …

X-Ray Diffraction Analysis of Airborne Particulates Collected by a Cascade Impactor Sampler. Phase Distribution Versus Particle Size

A Comparative Performance Study of a 1200 V Si and SiC MOSFET Intrinsic Diode on an Induction Heating Inverter

This paper presents a comparison of the behavior of the intrinsic diode of silicon (Si) and silicon carbide (SiC) MOSFETs. The study was done for 1200 V Si and SiC MOSFETs. The data sheet from manufacturers shows the characteristics of MOSFET' intrinsic diode when gate source voltage (VGS) is 0 V. There are applications where the MOSFET' intrinsic diode is used while VGS is different than 0 V. One of these applications is induction heating, where depending on the load and the regulation system, the diode can conduct a significant part of the inverter current. In most applications which use the MOSFET' intrinsic diode, the turn ON of the intrinsic diode happens at VGS = 0 V. After a blanking…

Quantitative x-ray diffraction phase analysis of coarse airborne particulate collected by cascade impactor sampling

Mineralogical composition of Castellon (Spanish Mediterranean coast) atmospheric aerosol was studied by X-ray diffraction by sampling with a cascade impactor without filters. Quantitative phase analysis of natural phases present in the atmospheric coarse aerosol was performed using a modified version of the computer program MENGE, that uses the standardless X-ray method developed by Rius for the quantitative analysis of multiphase mixtures, adapted for PC running. Presence of quartz, calcite and gypsum was identified in the atmospheric aerosol and we have quantified their amounts using the standardless method.

CCDC 119847: Experimental Crystal Structure Determination

Related Article: F.Hueso-Urena, M.N.Moreno-Carretero, A.L.Penas-Chamorro, J.M.Amigo, V.Esteve, T.Debaerdemaeker|1999|Polyhedron|18|3629|doi:10.1016/S0277-5387(99)00292-2

CCDC 121426: Experimental Crystal Structure Determination

Related Article: F.Hueso-Urena, M.N.Moreno-Carretero, A.L.Penas-Chamorro, J.M.Amigo, V.Esteve, T.Debaerdemaeker|1999|Polyhedron|18|3629|doi:10.1016/S0277-5387(99)00292-2

CCDC 120949: Experimental Crystal Structure Determination

Related Article: F.Hueso-Urena, M.N.Moreno-Carretero, A.L.Penas-Chamorro, J.M.Amigo, V.Esteve, T.Debaerdemaeker|1999|Polyhedron|18|3629|doi:10.1016/S0277-5387(99)00292-2

CCDC 113469: Experimental Crystal Structure Determination

Related Article: F.Hueso-Urena, A.L.Penas-Chamorro, M.N.Moreno-Carretero, J.M.Amigo, V.Esteve, T.Debaerdemaeker|1999|Polyhedron|18|2205|doi:10.1016/S0277-5387(99)00108-4