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Dive into the research topics where Francisco Javier Serrano is active.

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Featured researches published by Francisco Javier Serrano.


Journal of The European Ceramic Society | 2000

XRD microstructural analysis of mullites obtained from kaolinite–alumina mixtures

M.A. Sainz; Francisco Javier Serrano; J. M. Amigo; J. Bastida; A. C. Caballero

Abstract A microstructural study of mullite obtained by the reaction sintering of kaolinite–α–alumina mixtures in the range 1150–1700°C has been performed by using X-ray line profile analyses together with scanning and transmission electron microscopy equipped with microanalysis by energy dispersion (SEM-EDS, TEM-AEM). Two kinds of morphology corresponding to primary (elongated grains) and secondary (equiaxed grains) mullite have been observed. A bimodal crystallite size distribution has been detected through XRD microstructural analysis from 1300°C. The results obtained by this method are compared with SEM/TEM data.


Journal of The European Ceramic Society | 1997

Microstructural evolution and growth of crystallite size of mullite during thermal transformation of kyanite

M.A. Sainz; Francisco Javier Serrano; J. Bastida; A. C. Caballero

Abstract The microstructural evolution of mullite during the thermal transformation of kyanite has been studied in the temperature range 1200–1600 °C. The shape and size of the grains were analysed by means of SEM-EDS while crystallite size evolution was studied by X-ray line profile analyses. The results obtained showed that total transformation of kyanite to mullite takes place between 1350 and 1400 °C. At temperatures below 1350 °C needle-like mullite grains are always produced. At higher temperatures the mullite grains reveal rounded end platelet morphology. Evolution from needle-like to platelet shape was correlated with the X-ray data.


Clays and Clay Minerals | 2009

X-RAY DIFFRACTION LINE-BROADENING STUDY ON TWO VIBRATING, DRY-MILLING PROCEDURES IN KAOLINITES

Pablo Pardo; J. Bastida; Francisco Javier Serrano; Rafael Ibáñez; Marek Andrzej Kojdecki

Due to the great technological importance of the microstructure of kaolinite, characterizing its evolution during dry milling of kaolin and analyzing the microstructural information obtained from different methods were the main aims of this work. The microstructural alteration of kaolinite is evaluated by X-ray diffraction and electron microscopy methods, comparing the results obtained and analyzing the correlations between them. The Warren-Averbach and Voigt-function methods of X-ray diffraction microstructural analysis have been applied successfully to the study of the effects of two different, vibrating-cup dry-milling configurations in the microstructure of kaolinite from the reflections corresponding to (001) diffracting planes. The crystallite-size estimates obtained from the two methods correlate well. Field emission scanning electron microscopy measurements of kaolinite particle thickness are in good agreement with the crystallite size estimated by the two methods. The Warren-Averbach method also provided estimates of the contribution to line broadening. Vibrating-cup milling has been proved to be a more efficient method of strain comminution of kaolinites than other milling techniques, reaching extensive microstructural degradation within seconds.


Journal of Applied Crystallography | 2007

Microstructural evolution of mullites produced from single-phase gels

Marek Andrzej Kojdecki; Esther Ruiz de Sola; Francisco Javier Serrano; Estefanía Delgado-Pinar; M.M. Reventós; Vicente Esteve; J. M. Amigo; Javier Alarcón

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 patterns. The formation of mullites of homogeneous chemical composition and with unit-cell parameters depending almost linearly on the treatment temperature was found. Their compositions, expressed as alumina to silica molar ratio, were determined from the unit-cell parameters and were in the range of those characterizing primary and secondary mullites. Mullites processed at lower temperatures were accompanied by small amounts of vitreous phase. The crystalline microstructure of the obtained mullites was interpreted by means of a mathematical model of polycrystalline material, involving prevalent crystallite shape, volume-weighted crystallite size distribution and second-order crystalline lattice strain distribution as model parameters. The model parameters were determined for each sample by modelling its X-ray diffraction pattern and fitting it to a measured pattern. Bimodality of the size distribution was observed and explained as a consequence of two crystallite nucleation and growth processes, which started from small alumina-rich and alumina-poor domains, spontaneously formed in a precursor gel at early stages of heating. Images produced by scanning and transmission electron microscopy agreed well with the characteristics obtained from the analysis of the X-ray diffraction patterns.


Journal of Applied Crystallography | 2009

Comparative X-ray diffraction study of the crystalline microstructure of tetragonal and monoclinic vanadium-zirconium dioxide solid solutions produced from gel precursors

Marek Andrzej Kojdecki; Esther Ruiz de Sola; Francisco Javier Serrano; J. M. Amigo; Javier Alarcón

The microstructural characteristics of solid solutions, prepared by heating dried gel precursors with nominal compositions VxZr1−xO2 (0 ≤ x ≤ 0.1) at 723 and 1573 K, were determined from X-ray diffraction patterns. The crystalline microstructure of the resulting specimens, characterized by a prevalent crystallite shape, a volume-weighted crystallite size distribution and a second-order lattice strain distribution, was found to depend on the vanadium content. A characteristic feature of all size distributions was their bimodality, explained as a result of transformations between tetragonal and monoclinic phases during thermal treatment. A comparative study of the microstructure of both zirconia phases has been carried out, enabling reconstruction of a probable course of crystallization of both pure and vanadium-doped zirconias: on heating a sample, nucleation and the early growth stages involve crystallites of both phases; then on annealing and cooling, the crystallites of one phase transform into the other, depending on the thermal treatment temperature. Each logarithmic normal component of the crystallite size distribution of the resulting phase can be attributed to one of these processes. The limit of solubility of vanadium in tetragonal and monoclinic zirconia is estimated from the microstructural characteristics.


Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry | 2013

Crystal structure and microstructure of synthetic hexagonal magnesium–cobalt cordierite solid solutions (Mg2−2xCo2xAl4Si5O18)

Francisco Javier Serrano; Noemí Montoya; José L. Pizarro; M.M. Reventós; Marek Andrzej Kojdecki; J. M. Amigo; Javier Alarcón

Co(2+)-containing cordierite glasses, of nominal compositions (Mg(1-x)Co(x))2Al4Si5O18 (with x = 0, 0.2, 0.4, 0.6, 0.8 and 1), were prepared by melting colloidal gel precursors. After isothermal heating at 1273 K for around 28 h, a single-phase α-cordierite (high-temperature hexagonal polymorph) was synthesized. All materials were investigated using X-ray powder diffraction and field-emission scanning electron microscopy. The crystal structure and microstructure were determined from X-ray diffraction patterns. Rietveld refinement confirmed the formation of magnesium-cobalt cordierite solid solutions. The unit-cell volume increased with the increase of cobalt content in the starting glass. The crystalline microstructure of the cordierites was interpreted using a mathematical model of a polycrystalline material and characterized by prevalent crystallite shape, volume-weighted crystallite size distribution and second-order crystalline lattice-strain distribution. Hexagonal prismatic was the prevalent shape of α-cordierite crystallites. Bimodality in the size distribution was observed and interpreted as a consequence of two paths of the crystallization: the nucleation from glass of μ-cordierite, which transformed into α-cordierite with annealing, or the nucleation of α-cordierite directly from glass at high temperatures. Scanning electron microscopy images agreed well with crystalline microstructure characteristics determined from the X-ray diffraction line-profile analysis.


Journal of The European Ceramic Society | 2005

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

J. M. Amigo; Francisco Javier Serrano; Marek Andrzej Kojdecki; J. Bastida; Vicente Esteve; M.M. Reventós; Francisco Martı́


Journal of The European Ceramic Society | 2007

Solubility and microstructural development of TiO2-containing 3Al2O3·2SiO2 and 2Al2O3·SiO2 mullites obtained from single-phase gels

Esther Ruiz de Sola; Francisco Javier Serrano; Estefanía Delgado-Pinar; M.M. Reventós; Ana Isabel Pardo; Marek Andrzej Kojdecki; J. M. Amigo; Javier Alarcón


Journal of The European Ceramic Society | 2010

Effect of TiO2 on the mullite formation and mechanical properties of alumina porcelain

Noemí Montoya; Francisco Javier Serrano; M.M. Reventós; J. M. Amigo; Javier Alarcón


Crystal Research and Technology | 2006

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

E. Ruiz de Sola; Francisco Javier Serrano; Francisco Jose Torres; M.M. Reventós; Vicente Esteve; Marek Andrzej Kojdecki; J. M. Amigo; J. Alarcón

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J. M. Amigo

University of Valencia

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Marek Andrzej Kojdecki

Military University of Technology in Warsaw

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J. Bastida

University of Valencia

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A. C. Caballero

Spanish National Research Council

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M.A. Sainz

Spanish National Research Council

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