Person: Astilleros García-Monge, José Manuel
Loading...
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
15 results
Search Results
Now showing 1 - 10 of 15
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 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 El arte y la ciencia de los cristales(2014) López-Acevedo, Victoria; López Andrés, Sol; Sánchez Pastor, Nuria; Viedma Molero, Cristóbal; Martín-Vivaldi Caballero, Juan Luis; Astilleros García-Monge, José Manuel; Arroyo Rey, Xabier; Perles, Josefina; López Valero, Isabel- Project number: 62
Item La Cristalografía como plataforma para actividades de Aprendizaje-Servicio(2015) López Andrés, Sol; López-Acevedo Cornejo, Victoria; Astilleros García-Monge, José Manuel; Sánchez Pastor, Nuria; Gómez Sal, Pilar; Martín Alonso, Avelino; Perles, JosefinaCon motivo del Año Internacional de la Cristalografía en 2014, colectivos de cristalógrafos de todo el mundo, se han unido para desarrollar actividades de divulgación de éste área de conocimiento, basadas en la metodología Aprendizaje-Servicio (ApS) que fomenta el servicio comunitario y los valores participativos en centros de enseñanza. En este Proyecto, los colectivos de cristalógrafos implicados pertenecen a tres universidades de la Comunidad de Madrid: Universidad Complutense, Universidad de Alcalá y Universidad Autónoma. Una de las actividades llevadas a cabo ha sido el “Concurso de Cristalización en la Escuela”, que comenzó a realizarse en Andalucía hace ya 4 años y en 2014 se ha extendido a nivel nacional. Item Crecimiento epitaxial de celestina sobre la superficie (001) de la barita(Macla, 2004) Sánchez Pastor, Nuria; Pina Martínez, Carlos Manuel; Astilleros García-Monge, José Manuel; Fernández Díaz, María LourdesItem Estudio del Efecto del Ca en el Crecimiento y Hábito de la Barita(Macla, 2011) Ibáñez de Aldecoa, Juan; Astilleros García-Monge, José Manuel; Sánchez Pastor, Nuria; Fernández Díaz, María LourdesItem Agregados biomiméticos de calcita crecidos en hidrogel de gelatina: efecto combinado del Mg y la concentración de sólido en el gel(Macla, 2015) Nindiyasari, Fitriana; Griesshaber, Erika; Fernández Díaz, María Lourdes; Astilleros García-Monge, José Manuel; Sánchez Pastor, Nuria; Ziegler, Andreas; Schmahl, Wolfgang W.Item Influence of Gelatin Hydrogel Porosity on the Crystallization of CaCO3(Crystal growth and design, 2014) Nindiyasary, F.; Fernández Díaz, María Lourdes; Griesshaber, Erika; Astilleros García-Monge, José Manuel; Sánchez Pastor, Nuria; Schmahl, Wolfgang W.We investigated the influence of the porosity of the growth medium on the crystallization of calcium carbonate in hydrogels with different gelatin solid contents (2.5, 5, and 10 wt %). In all experiments, the precipitate consisted of calcite with occasional occurrences of some vaterite and aragonite. The calcite grew as compact radial intergrowths of crystals that show rhombohedral external faces. The crystal surfaces consist of identical 1−10 μm sized rhombohedral sub-blocks. Electron backscatter diffraction (EBSD) uncovered the radial intergrowth structure of the aggregates. EBSD also documented the internal microscale mosaicity and mesocrystal-like constitution of the gel-grown calcite. Raman spectroscopy and thermogravimetric analysis confirmed the presence of gelatin within the crystals. It reached up to ∼2 mass % in the calcite-gelatin composites that formed in hydrogels with 10 wt % gelatin content. Calcite morphology and mosaicity varied with the gelatin content of the hydrogel, such that an increase in gelatin content initiated the growth of smaller crystal aggregates having progressively rougher surfaces, increasing amounts of incorporated gel, and increasing degrees of misorientation in the internal mosaic structure. Apart from biospecific morphology, the gel growth experiment successfully mimics many characteristics of calcite biomineralization such as formation of a hierarchical hybrid composite, crystal mosaicity, and mesocrystal-like constitution.Item In Situ Nanoscale Observations of Metatorbernite Surfaces Interacted with Aqueous Solutions(Environmental science & technology, 2013) Astilleros García-Monge, José Manuel; Pinto, André Jorge; Gonçalves, Mario A.; Sánchez Pastor, Nuria; Fernández Díaz, María LourdesMetatorbernite (Cu(UO2)2(PO4)2·8H2O) has been identified in contaminated sediments as a phase controlling the fate of U. Here, we applied atomic force microscopy (AFM) to observe in situ the interaction between metatorbernite cleavage surfaces and flowing aqueous solutions (residence time = 1 min) with different pHs. In contact with deionized water the features of (001) surfaces barely modify. However, changes are remarkable both under acidic and basic conditions. In acidic solutions (pH = 2.5) metatorbernite surface develops a rough altered layer and large pits nucleate on it. The altered layer shows a low adhesion and is removed by the AFM tip during the scanning. The large pits spread rapidly, at few tens of nm/s, indicating a collapse of the structure. The combination of dissolution and the presence of defects in the metatorbernite structure can explain both the collapse process and the alteration of the surfaces under acidic conditions. Other mechanisms such as ion exchange reactions remain speculative. In NaOH solutions (pH = 11.5) metatorbernite dissolves by formation of etch pits bounded by steps parallel to ⟨100⟩, the direction of the most straight periodic bond chains (PBCs) in metatorbernite structure. These steps retreat at ∼0.15 nm/s. Under these conditions dissolution is promoted by the formation of stable uranyl carbonate complexes in solution.Item Influencia del Grupo Fosfato en la Morfología de los Cristales de Calcita (CaCO3)(Macla, 2011) Buey, Pablo del; Sánchez Pastor, Nuria; Astilleros García-Monge, José Manuel; Fernández Díaz, María Lourdes