Person: Astilleros García-Monge, José Manuel
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First Name
José Manuel
Last Name
Astilleros García-Monge
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Mineralogía y Petrología
Area
Cristalografía y Mineralogía
Identifiers
86 results
Search Results
Now showing 1 - 10 of 86
Item Estudio de la influencia del carbonato en el crecimiento de la barita a nanoescala.(Macla, 2004) Sánchez Pastor, Nuria; Pina Martínez, Carlos Manuel; Astilleros García-Monge, José Manuel; Fernández Díaz, María LourdesItem El empleo del AFM Hidrotermal (HAFM) en el estudio de la deshidratación térmica del yeso(Macla, 2004) Astilleros García-Monge, José Manuel; Jordan, G.Item Nanoscale observations of the effect of cobalt on calcite growth and dissolution(Journal of Crystal Growth, 2004) Freij, Sawsan J.; Putnis, Andrew; Astilleros García-Monge, José ManuelIn situ atomic force microscopy has been used to study the effect of dissolved cobalt on the growth and dissolution of calcite {10.4} surfaces. Growth experiments conducted in the presence of various cobalt concentrations revealed that the growth of the first layer proceeds with step growth and is faster than the growth in pure solution. The subsequent growth on the newly formed surfaces is much slower, although the solution supersaturation is kept constant. This difference in the step velocity leads to the temporary reproduction of the original surface topography (template effect). This demonstrates the role of the substrate surface structure in the crystal growth. In situ dissolution experiments conducted in the presence of cobalt revealed that cobalt is sorbed at the negative (acute) kinks leading to the formation of monomolecular semi-triangular etch pits.Item Geología de Grado en Química. Prácticas. 3. Periodicidad(Reduca. Geología, 2010) Astilleros García-Monge, José Manuel; López De Andrés, María Sol; Viedma Molero, Cristóbal; Vindel Catena, ElenaGeneralmente se define el cristal como un sólido en el que las innumerables partículas que lo constituyen están distribuidas periódicamente en las tres direcciones del espacio. Esta característica, la periodicidad, diferencia al cristal de todos los demás tipos de materiales y condiciona la existencia de otras propiedades, también exclusivas del medio cristalino, como son la simetría y la anisotropía. Esta práctica pretende que el alumno se familiarice con las herramientas básicas utilizadas en cristalografía para describir el medio periódico. La práctica presupone un conocimiento previo por parte del alumno del concepto de red cristalina y de cómo ésta se construye a partir de la traslación mediante vectores de los puntos equivalentes que la conforman. Debido a su utilidad pedagógica, gran parte de los ejercicios se realizarán sobre redes planas (bidimensionales), si bien en alguno de ellos se ha añadido una tercera dimensión, similar al mundo tridimensional del cristal real.Item Interaction of calcite with Cr(III) and evidence for direct inorganic formation of vaterite(Geochimica et cosmochimica acta, 2007) Godelitsas, Athanasios; Astilleros García-Monge, José Manuel; Hallam, K.R.; Wright, K.; Tomaschek, F.; Putnis, AndrewItem Crystallizationof ikaite and its pseudomorphic transformation into calcite: Raman spectroscopy evidence(Geochimica et cosmochimica acta, 2016) Sánchez Pastor, Nuria; Oehlerich, Markus; Astilleros García-Monge, José Manuel; Kalliwoda, Melanie; Mayr, Christoph C.; Fernández Díaz, María Lourdes; Schmahl, Wolfgang W.; Geochemical Society; ElsevierIkaite (CaCO3·6H2O) is a metastable phase that crystallizes in nature from alkaline waters with high phosphate concentrations at temperatures close to 0 °C. This mineral transforms into anhydrous calcium carbonate polymorphs when temperatures rise or when exposed to atmospheric conditions. During the transformation in some cases the shape of the original ikaite crystal is preserved as a pseudomorph. Pseudomorphs after ikaite are considered as a valuable paleoclimatic indicator. In this work we conducted ikaite crystal growth experiments at near-freezing temperatures using the single diffusion silica gel technique, prepared with a natural aqueous solution from the polymictic lake Laguna Potrok Aike (51°57′S, 70°23′W) in Patagonia, Argentina. The ikaite crystals were recovered from the gels and the transformation reactions were monitored by in situ Raman spectroscopy at two different temperatures. The first spectra collected showed the characteristic features of ikaite. In successive spectra new bands at 1072, 1081 and 1086 cm−1 and changes in the intensity of bands corresponding to the OH modes were observed. These changes in the Raman spectra were interpreted as corresponding to intermediate stages of the transformation of ikaite into calcite and/or vaterite. After a few hours, the characteristics of the Raman spectrum were consistent with those of calcite. While ikaite directly transforms into calcite at 10 °C in contact with air, at 20 °C this transformation involves the formation of intermediate, metastable vaterite. During the whole process the external shape of ikaite crystals was preserved. Therefore, this transformation showed the typical characteristics of a pseudomorphic mineral replacement, involving the generation of a large amount of porosity to account for the large difference in molar volumes between ikaite and calcite. A mechanism involving the coupled dissolution of ikaite and crystallization of calcite/vaterite is proposed for this replacement.Item Nanoscale processes during the interaction of aluminosilicate and carbonate mineral surfaces with acid mine drainage (AMD)(Geochimica et cosmochimica acta, 2009) Kollias, K.; Godelitsas, Athanasios; Astilleros García-Monge, José Manuel; Ladas, S.; Kennou, S.; Potamitis, C.; Zervou, M.; Lagoyiannis, A.; Harissopulos, S.; Mavromoustakos, Th.Item In situ HAFM study of the thermal dehydration on gypsum (010) surfaces(American Mineralogist, 2006) Jordan, Guntram; Astilleros García-Monge, José ManuelHydrothermal AFM has been used to study the thermal dehydration reaction on gypsum (010) surfaces in solutions at different saturation states, and in the absence of a bulk liquid phase. Experiments were carried out at temperatures ranging from 25 to 130 °C. Whereas supersaturated solutions (β = 1.8–5) caused gypsum growth in the entire temperature range, solutions close to equilibrium (β = 1.02) caused various responses of the gypsum surface. The most prominent was a sharp transition from fast growth to very fast dissolution at ∼120 °C suggesting a sudden nucleation of a phase more stable than gypsum. No structural relation could be found between the parental gypsum (010) surface and the crystallizing phase. In the absence of a bulk liquid phase, dehydration takes place via the nucleation and spreading of etch-pit like pattern. Laterally, the thermal etch pits spread in an unrestricted way. In the vertical direction, pit growth was limited to a few micrometers. Dehydration by monolayer pits and nucleation of the dehydration process at monolayer steps on the (010) surface were never observed. Thus, unlike growth or dissolution, surface energy related to kink sites or individual point defects seems to be insuffi cient to trigger dehydration. The temperature-dependent lateral pit growth yields an activation energy of 119 ± 11 kJ/mol. The product phase disintegrates at the parental surface into nano-size particles without any morphologically noticeable transition zone.Item Interaction of Calcium Carbonates with Lead in Aqueous Solutions(Environmental science & technology., 2003) Godelitsas, Athanasios; Astilleros García-Monge, José Manuel; Hallam, K.R.; Harissopoulos, Sotirios; Putnis, AndrewPure calcium carbonate (calcite and aragonite) solid materials of different particle size (100-200 ím fragments and millimeter-sized single crystals) were interacted with Pb in aqueous solutions at room temperature under atmosphericPCO2. In the case of the micrometer-sized samples, the macroscopic investigation using a batch-type treatment procedure (solutions between 10 and 1000 mg/L Pb) and ICP-AES, SEM-EDS, and powder-XRD showed that the metal is readily removed from the aqueous media by both materials and indicated the sorption processes (mainly surface precipitation leading to overgrowth of cerussite and hydrocerussite crystals) taking place in parallel with surface dissolution processes. The various processes occurring at the calcium carbonate solid-water interface were clearly distinguished and defined in the case of the millimeter-sized samples interacted with 1000 mg/L Pb using a combination of wet-chemical, in-situ (AFM) and exsitu (AFM, SEM) microscopic, and surface spectroscopic (XPS, 12C-RBS) techniques. The in-situ AFM data revealed the dissolution processes on the surface of the calcium carbonates and the simultaneous heterogeneous nucleation of lead carbonate phases and confirmed the secondary dissolution of lead carbonate crystals grown epitaxially from the initial nuclei. The XPS spectra confirmed that adsorption of Pb occurs simultaneously to dissolution at short interaction times (less than 10 min, prior to precipitation-nucleation/crystal growth) in the case of both CaCO3 polymorphs and that the calcite surface with adsorbed Pb may have an aragonite-type character. The 2CRBS spectra indicated that absorption (incorporation of Pb2+ ions) also takes place in parallel at the surface layers of the calcium carbonates, resulting in formation of solid solutions.Item The growth mechanisms of solid solutions crystallising from aqueous solutions(Chemical geology, 2004) Pina Martínez, Carlos Manuel; Putnis, Andrew; Astilleros García-Monge, José ManuelIn this paper, we present a generalisation of the classical growth rate equations to the case of crystallisation in solid solution–aqueous solution (SS-AS) systems. In these new equations, basic growth parameters, interfacial free energy and supersaturation are functions of the solid composition. Therefore, each equation describes, for a given aqueous solution, a growth rate distribution as a function of the solid composition. Different crystal growth models such as two-dimensional nucleation or spiral growth mechanisms provide different growth rate distributions. We have studied the general behaviour of growth rate equations in solid solution–aqueous solution (SS-AS) systems. Finally, we have applied the generalised growth rate equations to the BaxSr1xSO4–H2O SS-AS system. It allowed us to determine relationships between growth mechanisms and solid composition in such a model system. The result of our calculations were discussed and compared with previous experimental work on the BaxSr1xSO4–H2O SS-AS system.