Person:
García Baonza, Valentín

First Name

Valentín

Last Name

García Baonza

URI

https://hdl.handle.net/20.500.14352/76144

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Químicas

Area

Química Física

Identifiers

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Now showing 1 - 10 of 18

Computational Modeling of Tensile Stress Effects on the Structure and Stability of Prototypical Covalent and Layered Materials
(Nanomaterials, 2019) Chorfi, Hocine; Lobato Fernández, Álvaro; Boudjada, Fahima; Salvadó, Miguel A.; Franco, Ruth; García Baonza, Valentín; Recio, J. Manuel
Understanding the stability limit of crystalline materials under variable tensile stress conditions is of capital interest for technological applications. In this study, we present results from first-principles density functional theory calculations that quantitatively account for the response of selected covalent and layered materials to general stress conditions. In particular, we have evaluated the ideal strength along the main crystallographic directions of 3C and 2H polytypes of SiC, hexagonal ABA stacking of graphite and 2H-MoS 2 . Transverse superimposed stress on the tensile stress was taken into account in order to evaluate how the critical strength is affected by these multi-load conditions. In general, increasing transverse stress from negative to positive values leads to the expected decreasing of the critical strength. Few exceptions found in the compressive stress region correlate with the trends in the density of bonds along the directions with the unexpected behavior. In addition, we propose a modified spinodal equation of state able to accurately describe the calculated stress–strain curves. This analytical function is of general use and can also be applied to experimental data anticipating critical strengths and strain values, and for providing information on the energy stored in tensile stress processes.
Linear, Non-Conjugated Cyclic and Conjugated Cyclic Paraphenylene under Pressure
(Molecules, 2019) Peña-Álvarez, Miriam; Fanetti, Samuele; Falsini, Naomi; Novelli, Giulia; Casado, Juan; García Baonza, Valentín; Taravillo Corralo, Mercedes; Parsons, Simon; Bini, Roberto; Citroni, Margherita
The n-paraphenylene family comprises chains of phenylene units linked together by C-C bonds that are between single- and double-bonded, and where n corresponds to the number of phenylene units. In this work, we compare the response of the optical properties of different phenylene arrangements. We study linear chains (LPP), cyclic systems (CPPs), and non-conjugated cyclic systems with two hydrogenated phenylenes (H4[n]CPP). Particularly, the systems of interest in this work are [6]LPP, [12]- and [6]CPP and H4[6]CPP. This work combines Raman and infrared spectroscopies with absorption and fluorescence (one- and two-photon excitations) measured as a function of pressure up to maximum of about 25 GPa. Unprecedented crystallographic pressure-dependent results are shown on H4[n]CPP, revealing intramolecular π-π interactions upon compression. These intramolecular interactions justify the H4[n]CPP singular optical properties with increasing fluorescence lifetime as a function of pressure.
Charge analysis in (RE)CrO4 scheelites by combined Raman spectroscopy and computer simulations
(Journal of solid state chemistry, 2022) García Baonza, Valentín; Lobato Fernández, Álvaro; Recio, J. Manuel; Taravillo Corralo, Mercedes
The quest for structure-property relationships in scheelite-type (RE)CrO4 compounds (where RE is a rare earth element) is a difficult task due to the number of exceptions found in RE empirical trends and the uncommon Cr(V) oxidation state. In this work, we experimentally and computationally analyse how the stretching vibrational frequencies ν1(Ag) and ν3(Eg) associated with the [CrO4] tetrahedral units evolve in the (RE)CrO4 crystal family (RE ¼ Nd, Gd, Dy, Ho, and Lu). Since previously reported Cr–O distances and volume changes along with the RE series are not sufficiently accurate to explain the monotonic decrease observed for the ν1(Ag) and ν3(Eg) frequencies, a deeper analysis was performed involving the well-known fact that the bond strength (force constant) decreases as the interatomic distance increases. Our results demonstrates that structural and spectroscopic parameters can be reconciled with classical solid state chemistry ideas when charge effects are considered. This analysis provides a new method for predicting chromium oxidation states from Raman spectroscopy that can be generalised to the study of other crystal families.
Project number: PIMCD175/23-24
Tutoriales y videotutoriales de software de utilidad para Informática Aplicada a la Química
(2024) González Prieto, Rodrigo; Caceres Gianni, Jorge Omar; Cembellín Santos, Sara; Fernández López, Israel; García Baonza, Valentín; Rodríguez Bencomo, Juan José
Project number: 242
Laboratorio integrado de prácticas de simulación de fundamentos y procesos químicos con fluidos supercríticos
(2019) Calvo Garrido, Lourdes; Cabañas Poveda, Albertina; Pando García-Pumarino, Concepción; García Baonza, Valentín; González Mac-Dowell, Luis; Tirado Armesto, Diego Felipe; Cuadra Mendoza, Isaac Alfonso; Menéndez Carbajosa, Alicia Marta; Calvo Garrido, María Lourdes
El objetivo del proyecto ha sido crear un laboratorio integrado de prácticas de simulación relacionadas con fundamentos termodinámicos y procesos con fluidos supercríticos, destinado a los alumnos de Química e Ingeniería Química.
LZS-1, Lanzarote (Canary Island, Spain) lunar (Apollo 14) basaltic soil simulant
(Scientific reports, 2022) Alberquilla, Fernando; Martínez Frías, Jesús; García Baonza, Valentín; Lunar Hernández, María Del Rosario
The search for Terrestrial Analogues is essential for the development of future permanent or semi-permanent lunar bases. Terrestrial Analogues are zones where it is possible to probe not only scientific instruments, but also other astronaut capabilities in an environment that is similar to the geological context, geomorphology, mineralogy, geochemistry, etc. that we can find on Mars, the Moon and even asteroids. This work has focused on a multi-analytical characterization of Peñas de Tao geosite basalts in Lanzarote (Canary Islands, Spain). This characterization starts from a field campaign in which 3000 g of basalt rocks were selected. Subsequently, they were analysed by different techniques to determine their composition at a mineralogical and geochemical level, and the results were compared with data from other lunar simulants and from the Apollo 14 mission. After that, a set of petrophysical tests was carried out in order to determine its physical properties and evaluate its capacity as an analogous material for use in situ as a resource for further geological and astrobiological (future lunar habitability) essays.
Caracterización multianalítica (SEM-EDX, microsonda electrónica y espectroscopía Raman) de los cóndrulos y de la matriz de la condrita carbonácea de Allende
(Geogaceta, 2018) López Acosta, David; Martínez Frías, Jesús; García Baonza, Valentín; Lunar Hernández, María Del Rosario
Allende es un ejemplo emblemático de condrita carbonácea caída en Pueblito de Allende (México) en 1969. Este meteorito es especialmente importante debido a su composición primitiva, como uno de los principales representantes de los primeros estadios del Sistema Solar. En este estudio se ha llevado a cabo una nueva caracterización multianalítica de esta condrita, centrada en la mineralogía y la geoquímica de los cóndrulos y la matriz empleando varias técnicas: microscopía óptica, SEM-EDX, microsonda electrónica y espectroscopía Raman, siendo especialmente relevante estaúltima, que ha demostrado ser de gran utilidad aportando información sobre el mineral y su estructura.
Análisis de la condrita ordinaria Dalgety Downs (L4): Mineralogía, geoquímica y espectroscopía Raman
(Geogaceta, 2021) Caño Blanes, Andrés; Lunar Hernández, María Del Rosario; García Baonza, Valentín; Martínez Frías, Jesús
El meteorito de Dalgety Downs, hallado en el Desierto de Australia Occidental, es una condrita ordinaria muy poco estudiada, que sin embargo contiene una valiosa información acerca de la evolución de la materia primitiva del Sistema Solar y los procesos que le afectan. Este ejemplar presenta unas características texturales, mineralógicas y geoquímicas en la matriz y cóndrulos que revelan procesos metamórficos de temperaturas intermedias y eventos de impacto moderados, además de una intensa alteración desarrollada durante su entrada en la atmósfera terrestre y su posterior exposición al clima, en lo que se define como la costra de fusión. Entre los métodos empleados en este estudio destaca la espectroscopía Raman como herramienta de identificación mineralógica, técnica que ha demostrado una gran precisión en materiales geológicos y que será empleada en próximas misiones espaciales.
Caracterización multianalítica de basaltos de Lanzarote como simulante regolítico y recurso de habitabilidad lunar
(Geogaceta, 2022) Alberquilla, Fernando; Martínez Frías, Jesús; Lunar Hernández, María Del Rosario; García Baonza, Valentín
La búsqueda de análogos terrestres es crucial para el desarrollode futuras bases lunares permanentes o semipermanentes. Los análogos terrestres son regiones donde es posible probar no solo instrumental científico, sino también las capacidades de los astronautas en un entorno que, por su contexto geológico, geomorfológico, mineralógico, geoquímico, etc es similar al que podemos encontrar en Marte, la Luna e incluso asteroides. Este trabajo se ha centrado en la realización de una caracterización multianalítica de tres regiones de Lanzarote (Maciot, Tao y Lavas de Timanfaya) a través del empleo de diferentes técnicas geoquímicas y petrofísicas. Los resultados han sido comparados con los datos aportados por otros autores sobre muestras traídas de las misiones Apolo. Esto ha permitido determinar la analogía existente entre las regiones de estudio y la región de alunizaje del Apolo 14 conocida como Fra-Mauro. Además, se ha podido concluir qué recursos son potencialmente extraíbles del regolito lunar y su función en una futura base semipermanente. Por último, se propone la posibilidad de elaborar el primer simulante regolítico lunar usando basalto de Lanzarote.
Infrared spectroscopic study of the formation of fossil resin analogs with temperature using trans-communic acid as precursor
(Microchemical Journal, 2018) Rodríguez Montoro, Óscar; Lobato Fernández, Álvaro; García Baonza, Valentín; Taravillo Corralo, Mercedes
For million years resin exudates have undergone chemical alterations by heat, pressure, radiation, water, oxygen, microorganisms, and have suffered processes of sedimentation and diagenesis. These agents have affected the organic functional groups present in the terpenes of the resins, giving rise to what we nowadays know as fossil resins. In this work, we try to get further insight in the chemical formation of fossil resins. As the simulation of the natural process is quite complex, we have focused on the temperature induced reactivity of the trans-communic acid, the main component of the Class I resins. Using this terpene derivate as a very basic model of a resin exudate, we have monitored their thermal changes by infrared spectroscopy, Differential Scanning Calorimetry and Thermogravimetric Analysis within the range of 25 to 340 °C. The temperature-induced transformation, both in presence and absence of inert atmosphere, is discussed on the basis of the reactivity of the conjugated double-bond, the exocyclic bond and the carboxylic acid group present in the trans-communic acid. The results obtained in these series of experiments agree with the maturation scheme accepted in the literature for natural resins, i.e. an initial cross-linked polymerization and a subsequent maturation reaction. From combined DSC/TGA and infrared spectroscopy results, we conclude that chemical changes produced in the trans-communic acid in the range 130–175 °C may mimic the initial polymerization-like process in the natural resins, whereas those produced between 180 and 340 °C seem to correspond to the maturation pathways described in the literature for fossil resins Class Ib. Spectral assignment of the most relevant infrared-active modes of the trans-communic acid at 25 °C is also provided with the aid of Density Functional Theory calculations.