Detalle Profesor

Nuestros investigadores
Rafael Sirera Bejarano
Facultad de Ciencias. Universidad de Navarra
Líneas de investigación
Método sol-gel para la preparación de materiales. Preparación de láminas delgadas ferroeléctricas por métodos de depósito químico y fotoquímico de disoluciones., Caracterización composicional, estructural, microestructural y eléctrica de óxidos mixtos multifuncionales., Caracterización química, estructural y microestructural de cementos, aditivos y conglomerantes.
Publicaciones científicas más recientes (desde 2010)
Autores: Guembe-Michel, N.; Durán Benito, Adrián; Sirera Bejarano, Rafael; et al.
ISSN   1422-0067  Vol.   23    2  2022  págs.   685
Pseudopolyrotaxanes (PPRs) are supramolecular structures consisting of macrocycles able to thread on a linear polymer chain in a reversible, non-covalent way, often referred to in the literature as "molecular necklaces". While the synthesis and reaction mechanisms of these structures in solution have been widely described, their solvent-free production has received little attention, despite the advantages that this route may offer. We propose in this work a kinetic mechanism that describes the PPR formation in the solid phase as a process occurring in two consecutive stages. This mechanism has been used to investigate the spontaneous formation of a PPR that occurs when grinding alpha-Cyclodextrin (alpha-CD) with polyethylene glycol (PEG). In the threading stage, the inclusion of the polymer and subsequent release of the water molecules lodged in the cavity of the macrocycle cause vibrational changes that are reflected in the time-dependence of the FTIR-ATR spectra, while the further assembly of PPRs to form crystals produces characteristic reflections in the XRD patterns, due to the channel-like arrangement of CDs, that can be used to track the formation of the adduct in crystalline form. The effects that working variables have on the kinetics of the reaction, such as temperature, feed ratio, molar mass of the polymer and the introduction of an amorphous block in the polymer structure, have been investigated. The rate constants of the threading step increase with the temperature and the activation energy of the process increases at lower proportions of CD to PEG. This is attributed to the lower degree of covering of the polymer chain with CDs that reduces the hydrogen-bonding driven stabilization between adjacent macrocycles. The formation of crystalline PPR, which takes place slowly at room temperature, is markedly promoted at higher temperatures, with lower proportions of CD favoring both the formation and the growth of the crystals. The molar mass of the polymer does not modify the typical channel-like arrangement of packed PPRs but the conversion into crystalline PPR diminishes when using PEG1000 instead of PEG400. At a microscopic level, the crystals arrange into lamellar structures, in the order of hundreds of nm, embedded in an amorphous-like matrix. The introduction of a polypropylene oxide block in the structure of the polymer (Pluronic L62) renders poorer yields and a considerable loss of crystallinity of the product of the reaction. The methodology here proposed can be applied to the general case of inclusion complexes of CDs with drugs in the solid phase, or to multicomponent systems that contain polymers as excipients in pharmaceutical formulations along with CDs.
Autores: Bretos, I. , (Autor de correspondencia); Jimenez, R.; Ricote, J. ; et al.
ISSN   1616-301X  Vol.   30    32  2020  págs.   2001897
The effective incorporation of (multi)functional oxides into next-generation flexible electronics systems requires novel fabrication technologies that enable the direct integration of crystalline oxide layers in them. Unfortunately, this is considerably challenging due to the thermal incompatibility between the crystallization temperatures of metal oxides (>600 degrees C) and the thermal stability of the flexible polymer substrates conventionally used (<400 degrees C). Here, it is shown that BiFeO(3)thin films can be grown on flexible plastic by solution processing involving three different but complementary strategies to induce the crystallization of the perovskite phase at a lower temperature limit of 325 degrees C. This "three-in-one" approach is based on the synthesis of tailored metal precursors i) with a molecular structure resembling the crystalline structure of the oxide phase, which additionally allows both ii) photochemical and iii) internal combustion reactions taking place in the thin films. The flexible BiFeO(3)thin films obtained from a specifically designed molecular complex withN-methyldiethanolamine yield a large remnant polarization of 17.5 mu C cm(-2), also showing photovoltaic and photocatalytic effects. This result paves the way for the direct integration of an interesting class of oxides with photoferroelectric properties in flexible devices with multiple applications in information and communication technology, and energy.
Autores: Ruiz, V. M.; Sirera Bejarano, Rafael; Martinez, J. M. ; et al.
ISSN   0014-3057  Vol.   122  2020  págs.   109397
For the first time polymer-based graded nanocomposites were prepared by solution blow spinning, SBS, looking for new materials with optimal dielectric behavior. SBS was used as the processing method to apply layer by layer multi-walled carbon nanotubes, MWCNT, filled poly(vinylidene fluoride), PVDF, nanocomposites of well controlled compositions. Different configurations in terms of the disposition of layers with distinct concentration of MWCNT were considered. The structure, morphology and thermal behavior of the materials prepared were investigated so as their broadband dielectric properties in order to find and understand possible correlations. Morphological and slight structural changes were observed as a function of MWCNT concentration; however, they do not seem to be the main factors affecting the variations observed in the dielectric behavior of the materials under study. It was demonstrated that a particular design of PVDF based dielectrics, for which there is a particular gradient of MWCNT concentration, importantly increases the permittivity without increasing dielectric losses.
Autores: Durán Benito, Adrián; González Sánchez, Jesús Fidel; Fernández Álvarez, José María; et al.
ISSN   2073-4360  Vol.   10    8  2018  págs.   824
A new range of grouts prepared by air lime and metakaolin (MK) as a pozzolanic admixture has been obtained by using as dispersing agents two polymers, namely poly-naphthalene sulfonate (PNS) and lignosulfonate (LS), with the aim of improving the fluidity of the fresh grouts. Fluidity and setting times of the grouts were assessed. Differences in the molecular architecture and in the anionic charge density explained the different adsorption of the polymers and the different performance. The higher anionic charge of PNS and its linear shape explained its better adsorption and effectiveness. The pozzolanic reaction was favoured in grouts with PNS, achieving the highest values of compressive strength (4.8 MPa after 182 curing days). The addition of PNS on lime grouts slightly decreased the frost resistance of the grouts (from 24 freeze-thaw cycles for the polymer-free samples to 19 or 20 cycles with 0.5 or 1 wt % of PNS). After the magnesium sulphate attack, grouts were altered by decalcification of hydrated phases and by formation of hexahydrite and gypsum. A protective role of portlandite against magnesium sulphate attack was clearly identified. Accordingly, the polymer LS, which preserves a significant amount of Ca(OH)2, could be an alternative for the obtaining of grouts requiring high sulphate attack resistance.
Autores: Perez-Mezcua, D.; Bretos, I.; Jimenez, R.; et al.
ISSN   0928-0707  Vol.   81    2  2017  págs.   355 - 361
The non-equilibrium beta-Bi2O3 polymorph is stabilized in thin films by a photochemical synthesis method. A strong ultraviolet-absorbing bismuth(III)-N-methyldiethanolamine complex is synthesized in solution as an ideal precursor for the beta-Bi2O3 phase. Ultraviolet-light induces the formation of an amorphous -Bi-O-Bi- continuous network in the films deposited from the former solution that easily converts into the beta-Bi2O3 polymorph at a temperature as low as 250 A degrees C. The room temperature stabilization of the beta-Bi2O3 phase is confirmed by their structural characterization using four-circle X-ray diffractometry. This study unequivocally identified the tetragonal crystal structure of the beta-Bi2O3 polymorph in the films. The high phase purity of these beta-Bi2O3 films is responsible for their exceptional visible-light photocatalytic activity, thus enabling the applications of the films of this metastable phase at room-temperature conditions.
Autores: Pérez-Mezcua, D.; Calzada, M. L.; Bretos, I.; et al.
ISSN   0955-2219  Vol.   36    1  2016  págs.   89 - 100
The preparation of (Bi0.50Na0.50)1¿xBaxTiO3 films requires a compositional/structural control, as they determine the functionality of these materials. We report a systematic compositional and structural analysis on (Bi0.50Na0.50)1¿xBaxTiO3 films fabricated by chemical solution deposition. The effects of incorporating Na(I) and Bi(III) excesses are analyzed through the comparison of the compositional depth profiles of stoichiometric films (BNBT) and films containing excesses (BNBTxs). Heterogeneous compositional profiles with larger bismuth content close to the substrate and thicker film-substrate interfaces are observed in BNBTxs, unlike stoichiometric films, which show atomic concentrations that correspond to the nominal composition of the precursor solution. Excesses induce structural differences in depth, observing a shift of the region of coexistence of rhombohedral and tetragonal phases (morphotropic phase boundary) toward higher x values and the formation of thick film-substrate interfaces. In contrast, stoichiometric films have homogeneous compositional and structural profiles with the MPB placed close to that described for bulk ceramics.
Autores: Perez-Mezcua, M. D.; Bretos-Ullivarri, I.; Jimenez, R.; et al.
ISSN   2045-2322  Vol.   6    39561  2016 
The potential of UV-light for the photochemical synthesis and stabilization of non-equilibrium crystalline phases in thin films is demonstrated for the beta-Bi2O3 polymorph. The pure beta-Bi2O3 phase is thermodynamically stable at high temperature (450-667 degrees C), which limits its applications in devices. Here, a tailored UV-absorbing bismuth(III)-N-methyldiethanolamine complex is selected as an ideal precursor for this phase, in order to induce under UV-light the formation of a -Bi-O-Bi- continuous network in the deposited layers and the further conversion into the beta-Bi2O3 polymorph at a temperature as low as 250 degrees C. The stabilization of the beta-Bi2O3 films is confirmed by their conductivity behavior and a thorough characterization of their crystal structure. This is also supported by their remarkable photocatalytic activity. Besides, this processing method has allowed us for the first time the preparation of beta-Bi2O3 films on flexible plastic substrates, which opens new opportunities for using these materials in potential applications not available until now (e.g., flexible photocatalytic reactors, self-cleaning surfaces or wearable antimicrobial fabrics). Therefore, photochemical solution deposition (PCSD) demonstrates to be not only an efficient approach for the low temperature processing of oxide films, but also an excellent alternative for the stabilization of metastable phases.
Autores: Durán Benito, Adrián; Sirera Bejarano, Rafael; Pérez Nicolás, María; et al.
ISSN   0008-8846  Vol.   81  2016  págs.   1 - 15
The effect of chlorides and nitrates of Li(I), Cr(III), Zn(II), Cu(II), Pb(II) nitrate and Cr(VI) (chromate) on the early hydration of ternary cement system of calcium aluminates (CA, CA2, C12A7) was reported. Li(I) and Cr(III) caused a strong acceleration of the hydration, while Zn(II) as well as chromate gave rise to a slight acceleration. On the contrary, Pb(II) and Cu(II) retarded the hydration. A clear formation of AFm phases during the first hydration stages was found and related to the acceleration ability. Anions (nitrate or chloride as counterions or even chromate) were able to be incorporated into the interlayer space of AFm, yielding insoluble and stable compounds. A balance between the insolubility of the metal hydroxides (dependant on the low amphoteric character of the compound) and the ability of the formation of AFm hydrates seems to be very important to lean the equilibrium towards the retarding of the hydration or towards the acceleration, respectively.
Autores: Pérez Nicolás, María; Durán Benito, Adrián; Navarro Blasco, Íñigo; et al.
ISSN   0008-8846  Vol.   82  2016  págs.   11 - 22
Polynaphtalenesulfonate (PNS) and lignosulfonate (LS) were tested as superplasticizers in pastes and mortars of pure air lime and air lime with a pozzolanic additive, nanosilica (NS). LS showed a better plasticizing effect than PNS: the flowability of the samples with LS as well as the slump retention over time was larger. LS strongly hindered carbonation due to its ability to form Ca2+ complexes. In mortars with NS, PNS was seen to interfere with the C-S-H formation, resulting in lower mechanical strengths. Adsorption isotherms and zeta potential showed that PNS was more adsorbed than LS onto lime and C-S-H particles. PNS acted mainly through electrostatic repulsion owing to its high anionic charge density and flat adsorption. However, LS was more efficient as superplasticizer in air lime media, steric hindrance being the main mechanism responsible for avoiding flocculation. Furthermore, LS yielded high compressive strengths in mortars with NS.
Autores: Navarro Blasco, Íñigo; Durán Benito, Adrián; Pérez-Nicolás, M.; et al.
ISSN   0301-4797  Vol.   159  2015  págs.   288 - 300
Phosphate coating hazardous wastes originated from the automotive industry were efficiently encapsulated by an acid¿base reaction between phosphates present in the sludge and calcium aluminate cement, yielding very inert and stable monolithic blocks of amorphous calcium phosphate (ACP). Two different compositions of industrial sludge were characterized and loaded in ratios ranging from 10 to 50 wt.%. Setting times and compressive strengths were recorded to establish the feasibility of this method to achieve a good handling and a safe landfilling of these samples. Short solidification periods were found and leaching tests showed an excellent retention for toxic metals (Zn, Ni, Cu, Cr and Mn) and for organic matter. Retentions over 99.9% for Zn and Mn were observed even for loadings as high as 50 wt.% of the wastes. The formation of ACP phase of low porosity and high stability accounted for the effective immobilization of the hazardous components of the wastes.
Autores: Pérez-Mezcua, D.; Sirera Bejarano, Rafael; Jiménez, R.; et al.
ISSN   2050-7526  Vol.   2    41  2014  págs.   8750 - 8760
Novel synthetic methods in solution that reduce the formation temperature of bismuth-based electronic oxides are essential for their successful integration with substrates of low thermal stability within micro- and flexible-electronic devices. This has become crucial for these oxides, since they appear as promising low-toxic functional materials alternative to other electronic oxides containing heavy metals. However, this is a challenge, since the crystallization of bismuth oxides occurs at high temperatures. To overcome these problems, we synthesize here a UV-absorber charge transfer metal complex in solution between the Bi(III) ion and an alkanolamine, N-methyldiethanolamine (Bi(III)-mdea). We take advantage of the photoreactivity of this complex to prepare bismuth-based oxide thin films at low temperature, which cannot be achieved by traditional thermal processing methods. Room temperature stable oxide thin films of the high-temperature delta-Bi2O3 phase are prepared from these solutions by UV-irradiation and annealing at 350 degrees C. The efficiency of this synthetic strategy is additionally proven for the low temperature preparation of thin films of much more complex bismuth based functional oxides: the multiferroic bismuth ferrite, BiFeO3, and the relaxor-ferroelectric perovskite of bismuth, sodium and barium titanate, (Bi0.5Na0.5)(0.945)Ba0.055TiO3.
Autores: Navarro Blasco, Íñigo; Pérez-Nicolás, M.; Fernández Álvarez, José María; et al.
ISSN   0950-0618  Vol.   73  2014  págs.   1 - 12
Two polycarboxylate ether copolymers were assessed as superplasticizers (SPs) for hydrated lime pastes modified with two reactive compounds, nanosilica (NS) and ceramic metakaolin (MK). Characterization of the molecular structure of the SPs by Size Exclusion Chromatography, XRD, FTIR and MALDI-TOF (Matrix Assisted Laser Desorption Ionization Time-of-Flight) mass spectrometry was performed. The structures of the polymers were seen to be star- and worm-like shapes. A close relationship was found between the molecular architecture and the flowability of the pastes, being the star-shaped plasticizer the most efficient. Zeta potential assessment allowed us to elucidate a steric hindrance as the main action mechanism for these polymers. The large specific surface area of nanosilica led to a large SPs consumption as compared with metakaolin with lower surface area. However, SPs in MK¿lime samples were attached favourably on the C¿S¿H and aluminate hydrates, so that the dispersing action was greater with respect to NS¿lime suspensions.
Autores: Sirera Bejarano, Rafael; Álvarez Galindo, José Ignacio; Durán Benito, Adrián; et al.
ISSN   2255-453X  Vol.   2    1  2014  págs.   83 - 92
Los medios audiovisuales son herramientas adecuadas hoy en día para ilustrar el desarrollo de las clases magistrales impartidas por el profesor universitario. El alumno se desenvuelve con soltura en estos soportes, y la utilización de estos medios es un óptimo complemento para una buena comprensión del tema. Particularizando esta acción en estudios experimentales, como la Química, las ventajas que aporta el empleo de estos materiales son claras, tanto en el entendimiento de los temas como en el propio acercamiento del alumno a aspectos más prácticos y relacionados con el ejercicio profesional al que se dedicarán cuando finalicen los estudios. El presente trabajo evalúa los resultados de aplicar las nuevas tecnologías en la enseñanza de la Química a estudiantes de la Universidad de Navarra. Se pretende identificar elementos propios del ejercicio profesional del químico y relacionar los contenidos teórico-prácticos de las asignaturas con el mismo, consiguiendo además con ello un mejor conocimiento de la materia objeto de estudio. La percepción de los alumnos ha sido ciertamente positiva en términos de un incremento de interés por las materias implicadas y de una mejora en la comprensión de las mismas.
Autores: Perez-Mezcua, D.; Calzada, M. L.; Bretos, I.; et al.
ISSN   0366-3175  Vol.   53    1  2014  págs.   21 - 26
(Bi05Na05)(1-x)BaxTiO3, (BNBT), which exhibits compositions for the morphotropic phase boundary (MPB) where exist an intimate coexistence of the rhombohedral and tetragonal structures, is being considered as promising lead-free alternative to the well known Pb(Zr-x,Ti1-x)O-3 (PZT). In this work, BNBT thin films were fabricated by chemical solution deposition (CSD) with a wide range of compositions (x0.050-0.150) onto Pt / TiO2/ SiO2/ (100)Si substrates. Structural studies by X-ray diffraction (gimel(cu)1.5406 angstrom) using a four-circle goniometer were carried out to determine the crystalline structure of the films. Rietveld analysis of the experimental X-ray patterns showed different volume fractions of the rhombohedral and tetragonal phases as a function of the Ba2- content and the coexistence of both phases, characteristic of a MPB region, for x0.055-0.080. Finally, Rutherford backscattering experiments (RBS) were performed to determine the compositional profile of the films. This study revealed a homogenous composition of the BNBT films with abrupt film/ substrate interfaces.
Autores: Pérez-Mezcua, D.; Sirera Bejarano, Rafael; Bretos, I.; et al.
ISSN   0002-7820  Vol.   97    4  2014  págs.   1269 - 1275
In this work, ferroelectric (Bi0.5Na0.5)(1-x)BaxTiO3 thin films were fabricated by chemical solution deposition (CSD) with compositions x=0.050-0.150. Stoichiometric thin films (hereinafter BNBT) and others containing 10mol% excesses of Bi3+ and Na+ (BNBTxs) were spin coated onto Pt/TiO2/SiO2/(100)Si substrates and crystallized by rapid thermal processing at 650 degrees C for 60s in oxygen atmosphere. Crystalline structure is studied by X-ray diffraction using Cu anode ((Cu)=1.5406) and synchrotron radiation (=0.97354). Rietveld refinement showed the coexistence of rhombohedral/tetragonal phases in the BNBT films for x values close to those reported for (Bi0.5Na0.5)(1-x)BaxTiO3 bulk ceramics. Different volume fractions of the rhombohedral/tetragonal phases are detected as a function of the Ba2+ content. An apparent shift of the position of the morphotropic phase boundary (MPB) is observed in the BNBTxs films. Here, the MPB region appears for nominal Ba2+ molar values of x similar to 0.10 and the experiments using a grazing-incidence synchrotron radiation indicate the existence of a crystalline phase with pyrochlore structure at the film surface. Rutherford backscattering experiments (RBS) revealed that the bismuth excess is not volatilized during the crystallization of the BNBTxs films which present inhomogeneous compositional depth profile and thick BixPt bottom interfaces. The MPB BNBT films with x similar to 0.055 have a homogeneous compositional depth profile without appreciable bottom interfaces. Scanning electron micrographs reveal less porosity and higher grain sizes in the stoichiometric films than in those with Bi3+ and Na+ excesses.
Autores: Fernández Álvarez, José María; Navarro Blasco, Íñigo; Durán Benito, Adrián; et al.
ISSN   0301-4797  Vol.   140  2014  págs.   1 - 13
Polyphosphate-modified calcium aluminate cement matrices were prepared by using aqueous solutions polluted with toxic metals as mixing water to obtain waste-containing solid blocks with improved management and disposal. Synthetically contaminated waters containing either Pb or Cu or Zn were incorporated into phosphoaluminate cement mortars and the effects of the metal¿s presence on setting time and mechanical performance were assessed. Sorption and leaching tests were also executed and both retention and release patterns were investigated. For all three metals, high uptake capacities as well as percentages of retention larger than 99.9% were measured. Both Pb and Cu were seen to be largely compatible with this cementitious matrix, rendering the obtained blocks suitable for landfilling or for building purposes. However, Zn spoilt the compressive strength values because of its reaction with hydrogen phosphate anions, hindering the development of the binding matrix.
Autores: Navarro Blasco, Íñigo; Fernández Álvarez, José María; Durán Benito, Adrián; et al.
ISSN   0950-0618  Vol.   48  2013  págs.   218 - 228
The recycling of WFS in calcium aluminate cement mortars at high level of replacement (50%) was studied. Consistency and setting time were measured in fresh mortars. Two different curing conditions were used, the second one with the aim of enhancing the formation of stable cubic calcium aluminate hydrates. Compressive strength, pore size distribution and SEM examination were carried out to assess the effectiveness of CAC matrix in the recycling of WFS. The effect of the incorporation of a polymeric admixture - a chitosan derivative - was also explored. Leaching studies on hardened mortars of three target pollutants of the WFS (toxic metals Pb, Cr and Zn) were also done to evaluate their immobilization. By comparison with OPC mortars, the use of CAC showed several advantages, improving the compressive strength and the toxic metal retention.
Autores: Fernández Álvarez, José María; Durán Benito, Adrián; Navarro Blasco, Íñigo; et al.
ISSN   0008-8846  Vol.   43    1  2013  págs.   12 - 24
The effect of individual and combined addition of both nanosilica (NS) and polycarboxylate-ether plasticizer (PCE) admixtures on aerial lime mortars was studied. The sole incorporation of NS increased the water demand, as proved by the mini-spread flow test. An interaction between NS and hydrated lime particles was observed in fresh mixtures by means of particle size distribution studies, zeta potential measurements and optical microscopy, giving rise to agglomerates. On the other hand, the addition of PCE to a lime mortar increased the flowability and accelerated the setting process. PCE was shown to act in lime media as a deflocculating agent, reducing the particle size of the agglomerates through a steric hindrance mechanism. Mechanical strengths were improved in the presence of either NS or PCE, the optimum being attained in the combined presence of both admixtures that involved relevant microstructural modifications, as proved by pore size distributions and SEM observations.
Autores: Álvarez Galindo, José Ignacio; Fernández Álvarez, José María; Navarro Blasco, Íñigo; et al.
ISSN   1044-5803  Vol.   80  2013  págs.   36-49
The addition of a pozzolanic nanosized material, nanosilica (NS), onto lime binding materials was carried out with the aim of assessing the microstructural modifications attained by its presence that were related to the mechanical behavior. Simultaneously, a comparative study between five different drying methods for water removal was reported, and their influence on the pore structure evaluation is discussed. Solvent-exchange with isopropanol and freeze-drying methods were shown to remove the excess of free water efficiently, allowing us to measure the gel pores (< 10 nm) of the calcium silicate hydrated (C-S-H) phases and yielding the largest surface area values. By using vacuum drying, oven drying at 60ºC or oven drying at 105ºC macro-, meso- and micropores could not be properly measured. On the other hand, the addition of NS dramatically altered the mesopore range. As a result of the intercalation of NS particles between lime particles, a drop in the population of large and medium capillary pores (in the range of 20-100 nm) was observed, leading to reduced overall porosity. The NS was clearly proven to act as nanofiller. Finally, this filling effect of NS together with the development of C-S-H gel, as a consequence of the pozzolanictype reaction proved by the increase of population in the micropore range, notably enhanced the compressive strength of the lime binding materials, yielding values more than twice those of the NS-free materials.
Autores: Navarro Blasco, Íñigo; Durán Benito, Adrián; Sirera Bejarano, Rafael; et al.
ISSN   0304-3894  Vol.   260  2013  págs.   89-103
The ability of calcium aluminate cement (CAC) to encapsulate toxic metals (Pb, Zn and Cu) was assessed under two curing conditions. Changes in the consistency and in the setting time were found upon the addition of the nitrates of the target metals. Both Pb and Cu caused a delay in CAC hydration, while Zn accelerated the stiffening of the mortar. Compressive strengths of the metal-doped mortars, when initially cured at 60ºC / 100%RH, were comparable with that of the free-metal mortar. Three different pore size distribution patterns were identified and related to the compounds identified by XRD and SEM. Sorbent capacities of CAC for the toxic metals were excellent: a total uptake was achieved for up to 3 wt.% loading of the three metals. In this way, CAC mortars were perfectly able to encapsulate the toxic metals, allowing the use of CAC for waste management as proved by the leaching tests.
Autores: Martín Arbella, Nekane; Bretos, I.; Jiménez, R.; et al.
ISSN   0959-9428  Vol.   21    25  2011  págs.   9051 - 9059
New photosensitive precursors for the low-temperature preparation of ferroelectric PbTiO(3) thin films are obtained by using a sol-gel synthetic route. The reaction of N-methyldiethanolamine (MDEA) with lead acetate and titanium bis(acetylacetonate) diisopropoxide reagents leads to the formation of metal-MDEA complexes with a significant ultraviolet (UV) absorption due to the chromophore groups arisen from the orbital splitting between the respective metal atom and the organic ligand. Processes of transference of charge between the nitrogen and the metallic centre are responsible for the UV absorption in the resulting sols: ligand to metal charge transfer (LMCT) in the case of the Ti(IV) complex, d(0) element, and metal to ligand charge transfer (MLCT) in the case of the Pb(II) one, d(10) element. The enhanced photosensitivity of the precursor solutions provided by these complexes is exploited for the fabrication of ferroelectric PbTiO(3) films at temperatures compatible with silicon microelectronics (400 degrees C).
Autores: Martín Arbella, Nekane; Bretos, I.; Jiménez, R.; et al.
ISSN   0002-7820  Vol.   94    2  2011  págs.   396 - 403
Autores: González Sánchez, Jesús Fidel; Navarro Blasco, Íñigo; Durán Benito, Adrián; et al.
Libro: Proceedings PRO 130 : 5th Historic Mortars Conference
2019  págs.   330 - 345
This work reports the obtaining of lime-based grouts as repairing materials. Microsilica was added as pozzolanic additive to enhance the compressive strength of the hardened grouts. Sodium oleate, as water repellent admixture, and different superplasticizers (SPs) were also incorporated to reduce the water absorption and to enhance the injectability of the grouts. Polycarboxylate ether (PCE), polynaphthalene sulfonate (PNS), melamine sulfonate (MMS) and polyacrylic acid (PA) were tested as SPs. Regarding the fluidity of the grouts, PCE was seen to improve the injectability, followed by PNS, MMS and PA. However, PCE addition was also accompanied by a severe delay in the setting time. The other three superplasticizers did not provoke significant delays in the hardening of the samples. The water contact angle underwent an increase pointing to an effective hydrophobization of the surface as a consequence of the water repellent admixture. The combination with PCE was the most effective in keeping the water repellency in comparison with the control sample (lime grout + oleate). MMS yielded high compressive strengths and durability of the mortars, in the face of freezing-thawing cycles, was enhanced.
Autores: Durán Benito, Adrián; González Sánchez, Jesús Fidel; Navarro Blasco, Íñigo; et al.
Libro: Tradición, versatilidad e innovación en la cal: un material de excelencia
2018  págs.   228 - 240
El presente trabajo tiene como principal objetivo estudiar las interacciones que se producen cuando se adicionan separadamente dos superplastificantes (PNS ¿sulfonato de polinaftaleno- y LS ¿lignosulfonato-) a un conglomerante aéreo (cal aérea Cl 90-S) y a uno hidráulico formado por cal aérea a la que se le ha añadido metacaolín como material puzolánico, y los efectos que dichas adiciones tienen en las propiedades de los sistemas. Para la fabricación de los morteros, se empleó árido calcáreo. Adicionalmente, se efectuaron ensayos de durabilidad en morteros con la composición citada, sometiéndolos a ciclos de hielo-deshielo y a ataque con sulfatos. Aunque se realizaron algunas medidas con las pastas en estado fresco, la mayoría de los experimentos (resistencia a compresión y a flexión, TG-ATD, DRX, FTIR-ATR, porosimetría de intrusión de mercurio) se realizaron tras períodos de fraguado del mortero de 7, 28, 91, 182 y 365 días. Se detectaron fases silicatadas y silicoaluminatadas en los morteros estudiados, a pesar de que las experiencias se realizaron a temperatura ambiente y con un bajo porcentaje de material puzolánico (¿20 %). La presencia de LS impidió el proceso de carbonatación, lo que a su vez provocó un decrecimiento en los valores de resistencia mecánica cuando se trataba de morteros hidráulicos. Se observó asimismo una mayor porosidad y un mayor tamaño medio de poro en el caso de sistemas con LS. La durabilidad (ciclos hielo-deshielo) de los morteros mejoró notable
Autores: González Sánchez, Jesús Fidel; Navarro Blasco, Íñigo; Durán Benito, Adrián; et al.
Libro: Tradición, versatilidad e innovación en la cal: un material de excelencia
2018  págs.   251 - 262
Los morteros de relleno o inyección, especialmente destinados a reparación de cavidades y defectos de albañilería, deben fluir adecuadamente en estado fresco y combinar resistencia y durabilidad. Para conseguir algunas de estas características pueden utilizarse aditivos químicos: superplastificantes, para mejorar la fluidez; adiciones puzolánicas, para conseguir resistencias adecuadas en ambientes con limitado acceso de CO2 y una mejora de la durabilidad; e hidrofugantes, de manera que, sin perjudicar la permeabilidad de estos materiales al vapor de agua, se evite la penetración de agua por capilaridad mejorando la durabilidad. Sin embargo, en la mayor parte de los casos, toda la información disponible se circunscribe al efecto de un único aditivo, sin contemplar el posible efecto conjunto o incluso sinérgico de las combinaciones más interesantes de dos o más aditivos y/o adiciones puzolánicas. El estudio de las sinergias entre estos componentes ofrece posibilidades muy interesantes de avance científico-técnico. Precisamente este es el objetivo del trabajo: diseño de nuevos morteros de inyección de cal que puedan ser utilizados para la restauración del Patrimonio Edificado mediante combinación adecuada de aditivos superplastificantes (éteres de policarboxilato, condensados de naftaleno-formaldehído, sulfonato de melamina y ácido poliacrílico), hidrofugante (oleato sódico) y adiciones minerales puzolánicas (microsílice y metacaolín).
Autores: Durán Benito, Adrián; Sirera Bejarano, Rafael; Pérez Nicolás, María; et al.
Libro: Proceedings of the 4th Historic Mortars Conference HMC 2016
2016  págs.   383 - 390
A new range of repair lime mortars were obtained by using as superplasticizer a polynaphthalene sulfonate-based polymer (PNS) and metakaolin as pozzolanic addition. Adsorption isotherms showed that PNS exhibited a high affinity for air lime particles with 52.08 mg¿g-1 as maximum sorption capacity in pure air lime media. Mathematical treatment of experimental data showed an optimal adjustment to a Freundlich model, in which interactions arising from multilayer adsorption are taken into account. The experimental results suggested a great interaction of PNS with air lime media (pure air lime or air lime with MK). Zeta potential curves of air lime systems titrated with PNS showed a larger zeta potential reduction, giving rise to a charge reversal, as a consequence of the high anionic charge density of this polymer (2.44 meq of anionic charge¿g-1). A flat adsorption was proposed as the attachment model of this admixture, owing to its higher anionic charge density and to its linear shape. The electrostatic repulsion was then the main action mechanism to explain the PNS function. In the hardened state, the combination of PNS and MK resulted sometimes in moderate mechanical strength increases and in a clear enhancement of the durability in the face of freezing-thawing cycles.
Autores: Fernández Álvarez, José María; Pérez Nicolás, María; Durán Benito, Adrián; et al.
Libro: Proceedings of the 4th Historic Mortars Conference HMC 2016
2016  págs.   721 - 728
This contribution dealt with the design of different air lime mortars and pastes by combining a nanostructured pozzolanic additive, nanosilica, and different dispersing agents, superplasticizers (two different polycarboxylate ethers (PCE), a polynaphthalene sulfonate-based polymer (PNS) and a lignosulfonate (LS)). In pure air lime systems, the highest effectiveness was shown by the PCE1, whereas the PNS was the less effective superplasticizer. In samples with nanosilica, the PCE1 was also the most effective superplasticizer. LS was seen to be effective at low dosages. In the presence of the pozzolanic additive, there was a high consumption of polycarboxylates. Nanosilica provided no ¿active¿ adsorption sites, resulting in a slight decrease of the zeta potential values. PCE1 showed low adsorbed amounts, better dispersing action and required lower dosage of plasticizing agent. There was a positive combination between lime mortars with nanosilica and polycarboxylates, which resulted in a mechanical strength improvement. Also the combined presence of nanosilica, for example, with PNS or with LS yielded better compressive strengths, being LS more effective than PNS: SEM images showed the better formation of C-S-H phases in LS-mortars.
Autores: Pérez Nicolás, María; Navarro Blasco, Íñigo; Durán Benito, Adrián; et al.
Libro: Proceedings of the 4th Historic Mortars Conference HMC2016
2016  págs.   688 - 695
The obtaining of self-cleaning mortars is very interesting to apply them in Built Heritage. Atmospheric pollutants, mainly carbonaceous particles and gases like NOx and SO2 can lead to severe aesthetic and functional damages in artworks. In the case of mortars and renders, the use of photocatalysts -usually based on TiO2- can be worthy of consideration. Photocatalysts, after being activated by light, are able to oxidize pollutants avoiding their deposition onto building materials. In this work, different air lime mortars modified upon the addition of TiO2-based photocatalysts were obtained and studied. Photocatalysts can be incorporated in bulk and the changes in fresh state properties were studied as well as the effect of the presence of the photocatalysts on the pore structure and mechanical resistance. Finally, the photocatalytic efficiency of these materials was carried out by means of a NOx abatement test. Results showed that the presence of the photocatalysts had a positive impact on the preservation of the lime mortars characteristics.
Autores: Pérez Nicolás, María; Durán Benito, Adrián; Sirera Bejarano, Rafael; et al.
Libro: Proceedings of the 4th Historic Mortars Conference HMC 2016
2016  págs.   375 - 382
A superplasticizing admixture of natural origin, lignosulfonate (LS), was incorporated to air lime mortars sometimes modified with a pozzolanic additive, metakaolin, to obtain a new range of repair mortars to be applied in Built Heritage. LS improved the flowability of the air lime samples and showed good slump retention over time: for example, after 150 minutes of the air lime pastes preparation, blends with LS lost only ca. 13% of the slump value. Experimental results showed that LS interfered with the carbonation due to its ability to form Ca2+ complexes. Adsorption isotherms and zeta potential measurements showed that LS was scarcely adsorbed onto lime and C-S-H particles. Due to its branchy structure, LS exhibited an adsorption mechanism leading to steric hindrance as the main responsible mechanism for avoiding flocculation. The presence of free LS molecules in the dispersion was seen to improve the plasticizing effect of this polymer. Flexural and compressive strengths as well as the durability in the face of freezing-thawing cycles of these mortars were also determined to assess the applicability of these repair mortars.
Autores: Navarro Blasco, Íñigo; Sirera Bejarano, Rafael; Pérez Nicolás, María; et al.
Libro: Proceedings of the 14th International Congress on the Chemistry of Cement (CD): Section 6, Alternative binders
2015  págs.   1 - 11
The rationale is that polyphosphate-CAC matrices have shown interesting potential to solidify/stabilize heavy metals, owing to the aforementioned acid-base reaction that yields a compact and low porous matrix mainly composed of ACP - amorphous calcium phosphate -, which can be able to retain hazardous compounds. We aimed to take advantage of the reactivity of one of the sludge components: the sludges with relatively large concentrations of phosphate are expected to act themselves as reactants that, interacting with the CAC, could result in a very effective retaining system of the sludge constituents. Sludge samples from two locations have been incorporated in high proportion within the mix. We discussed the effects of the sludge on the CAC mortar and a possible interaction mechanism is provided.
Autores: Pérez Nicolás, María; Navarro Blasco, Íñigo; Durán Benito, Adrián; et al.
Libro: Proceedings of the 14th International Congress on the Chemistry of Cement (CD): Section 4: Admixtures
2015  págs.   1 - 14
Although CAC is used in many building as well as industrial structures, its modification upon addition of photocatalytic additives has not yet been addressed and that is precisely the purpose of the present work. We intend to obtain for the first time depolluting CAC mortars modified with different amounts of TiO2. The effect of the TiO2 incorporation on setting time, compressive strength and mineralogical composition of the CAC mortars will be assessed. PCO efficiency of these TiO2-bearing CAC mortars will be also measured by means of the NOx abatement. The modified depolluting mortars could be then applied in different tunnels, industrial floors and urban areas in which CACs are usually applied.
Autores: Durán Benito, Adrián; Navarro Blasco, Íñigo; Pérez Nicolás, María; et al.
Libro: Proceedings of the 14th International Congress on the Chemistry of Cement (CD): Section 4, Admixtures
2015  págs.   1 - 8
The behaviour of different superplasticizers admixtures was assessed for hydrated lime pastes and mortars. Sometimes, air lime pastes and mortars were modified with two supplementary cementing materials (SCMs), namely nanosilica (NS) and metakaolin (MK). Two different polycarboxylate ethers, a lignosulfonate and a naphthalene condensed sulfonate superplasticizer were added to lime pastes and mortars and their effects on fresh-state properties as well as on the mechanical strengths were evaluated. A close relationship was found between the molecular architecture of the plasticizers and the flowability of the pastes. Zeta potential assessment allowed us to elucidate the main action mechanisms for these admixtures. In the case of polycarboxylate ethers, the large specific surface area of nanosilica led to a large SPs consumption as compared with metakaolin with lower surface area. However, polycarboxylate ethers in MK-lime samples were attached favourably to the C-S-H and aluminate hydrates, so that the dispersing action was greater with respect to NS-lime suspensions.
Autores: Navarro Blasco, Íñigo; Durán Benito, Adrián; Fernández Álvarez, José María; et al.
Libro: Proceedings of the 3rd Historic Mortars Conference HMC 13
2013  págs.   1 - 8
This work deals with the effect of the nanosilica addition on the performance of aerial lime mortars. Several lime mortars were prepared and modified upon the addition of 3, 6, 10 and 20 wt.% of nanosilica. The presence of nanosilica increased the water demand of the fresh mixtures and reduced the appearance of superficial cracks after the spreading of the mortars onto a porous stone. Setting time underwent a delay when the amount of nanosilica ranged from 3 to 10 wt.%. However, samples with 20 wt.% of nanosilica showed a shortened setting time compared to plain lime mortars. Nanosilica reacted with Ca(OH)2 particles, yielding C-S-H compounds and, acting as a nanofiller, nanosilica also caused a pore blockage in the mesoporous range. These facts resulted in an increase in both compressive strength and durability after undergoing freezing-thawing processes. Overall, the addition of nanosilica clearly improves several characteristics of the aerial lime mortars in order to prepare enhanced mixtures to be used for restoration works.
Autores: Álvarez Galindo, José Ignacio (Editor); Fernández Álvarez, José María (Editor); Navarro Blasco, Íñigo (Editor); et al.
This book collects the abstracts of the communications presented in the 5th Historic Mortars Conference (HMC 2019) organized by the Heritage, Materials & Environment (MIMED) Research Group of the Chemistry Department of the University of Navarra at the School of Sciences in Pamplona from 19 to 21 June 2019.
Autores: Álvarez Galindo, José Ignacio (Editor); Fernández Álvarez, José María (Editor); Navarro Blasco, Íñigo (Editor); et al.
Proceedings of the 5th Historic Mortars Conference (HMC 2019) held at the University of Navarra in Pamplona from the 19th to the 21st June 2019.
Autores: Álvarez Galindo, José Ignacio (Editor); Fernández Álvarez, José María (Editor); Navarro Blasco, Íñigo (Editor); et al.
El Fórum Ibérico de la Cal, FICAL, es una asociación sin ánimo de lucro cuyo objetivo es el desarrollo de la investigación, la formación y la difusión de la producción y el uso de la cal. Después de las exitosas V Jornadas celebradas en el LNEC de Lisboa, la Universidad de Navarra toma el relevo y organizará en Pamplona, en la Facultad de Ciencias, las VI Jornadas FICAL, del 28 al 30 de mayo de 2018. Estas Jornadas están abiertas a participantes de distintas procedencias e intereses: restauradores, arquitectos y arquitectos técnicos, químicos, geólogos, ingenieros civiles y de materiales, historiadores, científicos, profesionales del sector industrial, estudiantes, empresas productoras¿ con el común denominador de conocer más posibilidades de aplicación, características, comportamiento y aspectos innovadores y tecnológicos en relación con la cal. Se conocen aplicaciones de la cal desde tiempos inmemoriales, particularmente en construcción: morteros, soportes decorativos y pictóricos. La cal es un material íntimamente ligado al Patrimonio Histórico-Artístico y se sigue produciendo a partir de las mismas materias primas. Destacan, entre sus características, la plasticidad de las argamasas que utilizan cal, su capacidad higroscópica y desinfectante, sus propiedades aislantes y su durabilidad. La cal es perfectamente compatible con estructuras antiguas, es idónea para procesos de restauración y rehabilitación, pero también tiene interés en obra nueva porque aporta estabilidad,
Actividad docente

Curso 2017 - 2018

- Química de la coordinación y organometálica (F.Ciencias). Universidad de Navarra - Facultad de Ciencias.

- Caracterización de sólidos inorgánicos (F.Ciencias). Universidad de Navarra - Facultad de Ciencias.

- Química del estado sólido (F.Ciencias). Universidad de Navarra - Facultad de Ciencias.

Otros méritos relevantes
Realiza regularmente informes científico-técnicos y periciales para empresas del sector farmacéutico fundamentalmente, pero también de los sectores automovilístico y alimenticio, entre otros (hasta la fecha ha elaborado y firmado unos 150 de los mencionados informes).