CHEMISTRY OF SOLID STATE

Author: GRACIA EDO LOURDES.
Year: 2004.
University: JAUME I DE CASTELLON [www.uji.es].
Place of defense: ESCUELA SUPERIOR DE TECNOLOGÍA Y CIENCIAS EXPERIMENTALES.
Place of preparation: ESCUELA SUPERIOR DE TECNOLOGIA Y CIENCIAS EXPERIMENTALES.

Summary: This doctoral thesis can be considered a continuation in the development and progress of the various lines of work in the solid state chemistry of the group's research and Computational Chemistry, in particular covers three distinct areas: 1, - The effect of pressure in crystalline solids, which has studied the understandability and the resulting polymorphism of spinel MgAl204, CdCr2Se4 and GdGa2Se4, molecular CO2 and its solid phase transitions towards polymeric structures; crystal TiO2 comparing the behavior of its natural phases. 2-Phenomena dedifusión of certain impurities in metal surface of palladium. It also has studied the diffusion of lithium ions in WO3, with important applications in electrocromismo and batteries. 3-reactivity of clusters of transition metal oxides in which two different electronic states multiplicities of spin, have studied the reaction mechanisms of cation VO2 + with hydrocarbon ethylene, ethane and propene, the reactivity of certain clusters niobium oxide and its related oxihidróxidos, the study of several reactions catalyzed by water, acting giver and proton acceptor.

Author: ANSÓN CASAOS ALEJANDRO.
Year: 2004.
University: ZARAGOZA [www.unizar.es].
Place of defense: INSTITUTO DE CARBOQUÍMICA, CSIC.
Place of preparation: INSTITUTO DE CARBOQUÍMICA, CSIC.

Author: Parra García Vicente.
Year: 2005.
University: VALLADOLID [www.uva.es].
Place of defense: E. T. S. Ingenieros Industriales.
Place of preparation: E. T. S. Ingerieros Industriales.

Summary: Development of sensors based on materials molecular electroactivos essentially derived from metaloftalocianinas (mono and bisftalocianinas) and perilenos (imido, diimido). Its detection is the voltammetry, and are used for the creation of a new prototype electronic language, technical analysis of the latest generation, whose concept of analysis differs from the hitherto known in the study of liquid samples. These multi systems (networks of sensors), coupled with an adequate pool of data analysis techniques multivariate can obtain information environment easily achieved through the use of individual sensors, selective: show a kind of collective information of the sample, thanks to profiles of selectivity and sensitivity crusade treasure sensors members of the network compared to the multiple components of a sample. In particular, this thesis has been devoted to the study of discriminatory wine shows great interest in our country, characterized by its complex chemistry and its relationship with human sensory techniques for characterization. Here is one of the pillars of this thesis, comparing the sensory analysis with the mail.

Author: ORTIZ DE ZÁRATE DÍAZ DAVID.
Year: 2005.
University: VALENCIA [www.uv.es].
Place of defense: FACULTAT DE QUÍMICA.
Place of preparation: INSTITUT DE CIÈNCIA DELS MATERIALS DE LA UNIVERSITAT DE VALÈNCIA.

Summary: THE EFFORT FOR THIS THESIS RESEARCH HAS BEEN FOCUSING ON THE RATIONALIZATION OF THE CHEMICAL PROCESSES TO ALLOW GENERALIZACION OF METHOD OF ATRANOS FOR SYNTHESIS OF VERY DIFFERENT NANOMATERIALES: SOLID MESOPOROSOS BIMODALES (M-UVM-7 And HPNOs) MESOPOROSOS UNIMODALES ( UVM-11), NANOPARTÍCULAS THICK AND POROUS, ALL THAT LOGRANDO AN INTEGRATION OF HIGH FUNCTIONAL GROUPS (OR OTHER METALS ORGANIC) IN THE MATRIX INORGANIC SILÍCEA THAT COMPONE THE NANOMATERIAL. AT THE SAME TIME, HE HAS ACHIEVED THE PREPARATION OF THE FIRST OXIDES CAPAS DELGADAS OF MIXED METAL OF TRANSITION MULTINANOCRISTALINAS LISTED IN LITERATURE.

Author: MARQUES ARIAS MIRIAM.
Year: 2005.
University: OVIEDO [www.uniovi.es].
Place of defense: FACULTAD DE QUÍMICAS.
Place of preparation: FACULTAD DE QUÍMICAS.

Summary: This thesis contains the results of theoretical research aimed at understanding and computational properties, phenomena and processes that exhibit crystalline solids to varying conditions of pressure and temperature. It is divided into two parts. The first is devoted to the theoretical and methodological formalism. It addresses the fundamentals cristalográficos and electronic structure, not empirical algorithms for obtaining equations of state and theoretical methods for evaluating elastic constants, crystal and vibration scan the topology of the electron density. The second part presents simulations mecánico-cuánticas conducted in a collection of crystal systems that cover the entire spectrum of the types of bond traditional ion (halides), polarized (oxides and seleniuros), covalent (nitrides) cash (AI) and molecular (CO2). It identifies essentially crystalline geometries, equations of state and polymorphic sequences induced pressure in these systems and adopt criteria microscopic rationalization of the results using the local environments of its constituent atoms and the topology of the electron density. The study leads to the establishment of strategies and rigorous calculation modeling interpretation of a general nature. Highlights, including the model of parent metal anions in the generation of equations of state and atomic polyhedral and design based on arguments of symmetry of proposed mechanisms transitions gas.

Author: CASTRO COUCEIRO ADA.
Year: 2005.
University: A CORUÑA [www.udc.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: This work was performed characterization of dielectric compounds with different order of loading. In most of the materials were studied at room temperature dielectric constants that remained extraordinarily high over a wide range of frequencies. The realization of measures permitivity dielectric material in these samples with different grain sizes, using different types of contacts with pills or different thickness varied dramatically the values of their parameters dielectrics. This fact suggests that extrinsic factors to the materials were playing a role in the dielectric properties developed by them. All materials were studied by the technique of spectroscopy impedances, which showed that, indeed, the dielectric response was obtained in most cases debiada the interaction of different elements or regions with different resistivity of the material. Thus, most of the systems studied are behave in a manner similar to the so-called multilayer capacitors, which would be largely responsible for the huge values obtained for the dielectric constants. These effects extrinsic contributing so crucial to the dielectric properties of our systems are manifested mainly to low frequency and high temperatures that depend on the specific type of material. Therefore, in most cases it was impossible to observe the response of the media to the temperature at which the phenomenon was taking place in order to load. In any case, the dielectric constants obtained for these compounds are superior to those expected for conventional oxides. Moreover, in many cases, the parameters obtained dielectrics make these materials are attractive from a technological point of view.

Author: MASO CARCASES NAHUM.
Year: 2005.
University: JAUME I DE CASTELLON [www.uji.es].
Place of defense: ESC. SUP.DE TECN.A Y CIENCIAS EXPERIMENTALES.
Place of preparation: ESC. SUP.DE TECN. Y CIENCIAS EXPERIMENTALES.

Summary: In this thesis describes a sol-gel synthesis route alternative in obtaining compounds in the system BaO-TiO2, from barium acetate and isopropóxido titanium (IV), which gels obtained homogenous and transparent room temperature. The properties have been studied structural, electrical and microstructural polycrystalline ceramic samples of BaTi2O5 and Ba6Ti17O40, as well as the solutions sound BaTi1-xFexO3-, 0? X? 0.1, and BaTi1-5xNb4xO3, 0? X? 0,015. The BaTi2O5 shows behavior ferroeléctrico and their electrical properties are highly dependent on the conditions of calcination. The Ba6Ti17O40 is an excellent dielectric with a fairly high permitivity independent of temperature. The electrical properties of the samples based on the dissolution solid BaTi1-xFexO3- are sensitive to heat treatment, with a partial oxidation ions Fe3 + Fe4 + at temperatures below 700Â ° C. The loss of oxygen during the process of roasting is the most probable mechanism of the observed changes in the electrical properties of the samples based on the dissolution solid BaTi1-5xNb4xO3.

Author: LEÓN REINA LAURA.
Year: 2005.
University: MÁLAGA [www.uma.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: Fuel cells are electrochemical devices that convert chemical energy into electrical energy with an efficiency exceeding 95% theoretical and minimal emission of pollutants. In fuel cells solid oxide (SOFC), the cathode and anode are separated by a ceramic electrolyte, which must have high oxide ion conductivity, good chemical compatibility with the electrodes and low thermal expansion. One of the most promising candidates to replace the YSZ as SOFC electrolyte in batteries, is the system type apatito of general formula A10-x (MO4) 6O2 + (where A is a trivalent cation, for example The; a tetravalent and M, for example If). The oxoapatitos lanthanum have high values of oxide ion conductivity as a result of the existence of a mechanism for driving interstitial instead of the typical mechanism through vacancies in oxide ion conductors with fluorite structure or perovskita. We have determined the crystal structures of various series oxoapatitos lanthanum at room temperature and high temperatures using the method of Rietveld with neutron diffraction data, both longiitud wave as constant flight time. Some of the compositions were studied: La9.33 (SiO4) 6O2, La9.33 (Si0.5Ge0.5O4) 6O2, La9.50 (Si0.916Al0.083O4) O2, La9.50 (Ge0.916Al0.083O4) 6 O2, La8Sr2 (SiO4) 6O2 and La8Sr2 (GeO4) 6O2, all estequiométricas oxygen. The presence of Ge and / or Al gives rise to more flexible links that increase the amount of O and therefore interstitial oxygen vacancy in the axis C. Have also been studied composition with excess oxygen, as is the case with La9.55 (SiO4) 6O3.32, La9.60 (GeO4) 6O2.4 and La9Sr1 (Si5.5Al0.5O24) O2.25. Having oxygen content in excess of 26, all oxide anions present in a different position from that of O (4) because this site Crystallographic has no place so much extra oxygen. Such ion oxide takes two positions critalográficas different: 1-A when vacancies on the site of lanthanum and that is the same in which he puts the O (5) in the samples estequiométricas. 2-Other when the site is fully occupied lanthanum, a position that avoids the O (3) to be closer to the center of genetic channels and therefore O (4). The characterization using electrical impedances spectroscopy confirmed that these materials have a conductivity comparable to that of YSZ (but at lower temperature) and a smaller activation energy (range 0.6-0.8 eV). The composition KLa9.50 (Ge0.916Al0.083O4) 6O2 presents conductividades even higher than the GDC to 600Â ° C and YSZ wide range of temperatures means. The measurements made using techniques of direct current ( "ion-blocking" and fem) show that the value of electronic conductivity is negligible in the range of oxygen partial pressures from 0.21 to 10-21 atm, where the number of ion transport is from 0.99. Finally preliminary studies by FCT (Fuel Cell Test) of the composition La9.33 (SiO4) 6O2 have provided encouraging results for future studies that will enable eluso this and other oxoapatitos as electrolyte fuel cells.

Author: PALACIOS CLEMENTE PABLO.
Year: 2005.
University: POLITÉCNICA DE MADRID [www.upm.es].
Place of defense: ESCUELA TECNICA SUPERIOR DE INGENIEROS DE TELECOMUNICACIÓN.
Place of preparation: ESCUELA TÉCNICA SUPERIOR DE INGENIEROS DE TELECOMUNICACIÓN.

Summary: This thesis presents a theoretical study of quantum methods erector of different types of materials that may have application as a high-efficiency photovoltaic materials. The high efficiency of these materials would be provided by the existence of an extra electronic band, which called intermediate band, located within the forbidden band of a conventional semiconductor. This band has to meet various requirements for giving high efficiency proposal has to be partially filled, isolated within the forbidden band and show some width: The research work done in this thesis has been to the systematic study of alloys three main types of semiconductor materials, bandwidth banned near 2.1 eV: derived from III-V semiconductor type GaP derivatives chalcopyrites type CuGaS2 and derivatives of spinel type Mgln2S4. The alloys studied under investigation for the formation of the intermediate band characteristics, usually generated by partial replacement of group III atoms (Gallium for the first two types of materials, and for Indico spinel), transition metals with electrons 3 d, mainly titanium and other metals in the same series V, Cr and Mn. For the location of the calculations ab-initio, has used the theory of functional density (DFT), with the approximations of both local density (LDA), as gradients (EMG) with and without polarization spín. It has been used in addition to these corrections approaches to improving the performance as are the methods for exchanging accurate and inclusion of a term correction type Hubbard.