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
17 results
Search Results
Now showing 1 - 10 of 17
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 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 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.Item Nanoscale observations of the epitaxial growth of hashemite on barite (001)(Surface science, 2005) Shtukenberg, Alexander G.; Astilleros García-Monge, José Manuel; Putnis, AndrewThe heteroepitaxial growth of hashemite BaCrO4 on barite BaSO4(001) from supersaturated aqueous solutions was observed in situ using an atomic force microscope (AFM). It was shown that the first hashemite layer grows via two-dimensional nucleation easily forming a complete epitaxial layer,which is likely to have a low level of intrinsic stress. Two-dimensional nucleation of the second and subsequent layers proceeds with significantly lower rates,and growth occurs with lower step velocities. These layers seem to have significant level of intrinsic stress and tend to reduce it via the formation of free surface normal to the growth layer (holes in the layer,dendrite-like shape of nuclei and steps,preferable formation of nuclei at the step edges). As a result,the initially flat surface becomes rough. The process described corresponds to the Stranski-Krastanov epitaxial growth mode, which is well known for growth of semiconductor and metal films but not previously recognised for crystals grown from aqueous solutions.Item Microscopic and spectroscopic investigation of the calcite surface interacted with Hg(II) in aqueous solutions(Mineralogical magazine, 2003) Godelitsas, Athanasios; Astilleros García-Monge, José Manuel; Hallam, K.R.; Löns, J.; Putnis, AndrewThe interaction of the {101¯4} cleavage surface of calcite with Hg(CH3COO)2 aqueous solutions with concentration of 5 mM Hg(II) (pH ≈3.5), was investigated using microscopic and spectroscopic techniques. In situ atomic force microscopy experiments showed that surface microtopography changes significantly as a result of the interaction, and that the initial rhombic etch pits induced by H2O dissolution are rapidly transformed to deeper etch pits exhibiting an unusual triangular shape. The growth of these etch pits is strongly anisotropic, moving faster along the [22¯1] direction than along the [010] direction (with step-retreat velocities of ~12 nm s –1 and ~4 nm s–1, respectively). The modified etch pits are due to Hg(II) sorption in the surface, rather than due to the effect of the acetate anion. The sorption (adsorption and probably absorption also) of Hg(II), in the first minutes of the interaction, is shown by X-ray photoelectron spectroscopy. After ~2 h, the triangular etch pits are interconnected to form larger hexagonal etch pits, while Hg(II)-bearing phases (confirmed later by SEM-EDS) grow onto the surface through a heterogeneous nucleation process. The crystal growth of orthorhombic (montroydite-type) hydrated Hg(II) oxide (HgO·nH2O) on the surface of calcite was confirmed by XRD patterns and FT-IR spectra from samples exposed for longer times to Hg(CH3COO)2 solution.Item Comment: supersaturation in binary solid solution-aqueous solution systems (Comment on “Crystallization kinetics in binary solid solution – aqueous solution systems” by Alexander G. Shtukenberg, Yurii O. Punin and Pavel Azimov, American Journal of Science, v. 306, p. 553–574.)(American Journal of Science, 2007) Prieto Rubio, Manuel; Astilleros García-Monge, José Manuel; Pina Martínez, Carlos Manuel; Fernández Díaz, María Lourdes; Putnis, AndrewItem Metastable phenomena on calcite {1014} surfaces growing from Sr2+–Ca2+–CO3 2- aqueous solutions(Chemical geology, 2003) Astilleros García-Monge, José Manuel; Pina Martínez, Carlos Manuel; Fernández Díaz, María Lourdes; Putnis, AndrewIn situ atomic force microscopy (AFM) experiments, scanning electron microscopy (SEM) imaging and composition analysis, and X-ray diffraction have provided information about the growth, dissolution and transformation processes promoted by Sr2 + –Ca2 + –CO3 2 aqueous solutions in contact with calcite {101¯4} surfaces. Experiments have shown a wide variety of surface phenomena, such as the influence of the Sr-bearing newly-formed surface on the subsequent growth (template effect), the growth and subsequent dissolution of surfaces and the nucleation of secondary three-dimensional nuclei on calcite surfaces. These phenomena reveal the metastability of the crystallisation system and are a consequence of the interplay between thermodynamics (the relative stability of the two calcite and aragonite structure solid solutions that can be formed), supersaturation of the aqueous solution with respect to the two possible solid solutions, and the crystallographic control of the surfaces on cation incorporation.Item Molecular-scale surface processes during the growth of calcite in the presence of manganese(Geochimica et cosmochimica acta, 2002) Astilleros García-Monge, José Manuel; Pina Martínez, Carlos Manuel; Fernández Díaz, María Lourdes; Putnis, AndrewAbstract—This paper deals with the growth behaviour of the Mn-Ca-CO3-H2O solid solution-aqueous solution system on calcite {1014} surfaces. This system represents a model example, which allows us to study the effect of a number of controlling factors on the crystallisation: (1) the supersaturation function, (x), and nucleation rate function, J(x), for the Mn-Ca-CO3-H2O system, (2) the relationship of such functions to the molecular scale growth mechanisms operating on growing surfaces, and (3) the surface structure of the calcite {1014} faces. In situ atomic force microscopy (AFM) growth experiments revealed a wide variety of surface phenomena, such as the transition between growth mechanisms, anisotropic changes in the step rates, and the influence of the Mn-bearing newly formed surface on subsequent growth (step stoppage followed by the formation of two-dimensional nuclei and the reproduction of the original calcite {1014} surface microtopography). These phenomena result from the interplay between the controlling parameters and are explained in those terms.Item Nanoscale phenomena during the growth of solid solutions on calcite {101¯4} surfaces(Chemical geology, 2006) Astilleros García-Monge, José Manuel; Pina Martínez, Carlos Manuel; Fernández Díaz, María Lourdes; Prieto Rubio, Manuel; Putnis, AndrewThis work deals with the growth behaviour of calcite {101¯4} surfaces in contact with multicomponent aqueous solutions containing divalent cations (Ba2+, Sr2+, Mn2+, Cd2+, or Mg2+). The result is the formation of solid solutions, with calcite or aragonite as one of the end-members. In situ atomic force microscopy has revealed a wide variety of surface phenomena occurring during the formation of these solid solutions. Among them are: (1) the thickening of growth steps and the subsequent dissolution of surfaces followed by the nucleation of secondary three-dimensional nuclei on calcite surfaces, (2) the transition between growth mechanisms, (3) the formation of an epitaxial layer that armours the substrate from further dissolution and (4) the inhibitory effect of the newly formed surface on the subsequent growth (template effect). The two last phenomena can considerably limit coprecipitation as an effective mechanism for divalent metal uptake. All the phenomena described are a consequence of the interplay between thermodynamics, supersaturation of the aqueous solution with respect to the possible solid solutions and the crystallographic control of the surfaces on the cation incorporation, and indicates that there are many differences between the crystal growth of solid solutions and phases with fixed composition.