L. S. Gomez-Villalba

Spanish National Research Council | CSIC · Institute of Geosciences

Nanotechnology has allowed for significant progress in architectural, artistic, archaeological, or museum heritage conservation for repairing and preventing damages produced by deterioration agents (weathering, contaminants, or biological actions). This review analyzes the current treatments using nanomaterials, including consolidants, biocides, hy...

In search of compatible materials to speed up the strength and carbonation in lime mortars, nanoparticles show significant potential. This research explores the mechanical and physical characteristics of air lime mortars with silica sand and two types of dispersions based on nanoportlandite (nP) and nanosilica (nS) used as additions according to di...

This work studies the formation of calcium silicate hydrates (C‐S‐H) in lime mortars prepared with additions of nano Ca (OH)2 and nanoSiO2 at 23.3 °C. Mineral identification was carried out by X ray diffraction after 10, 30, 90, and 120 days of curing. The nanoscale study starts from the generation of amorphous phases until the development of cryst...

This study presents the advances in the field of ZnO/Ag catalysts from the synthesis of hierarchical ZnO nanowires (NWs) decorated with Ag nanoparticles, prepared by a facile solvothermal method at 120°C. It evaluates the photocatalytic efficiency from studying the time reaction of Ag/Zn concentration ratio and the presence of cetyltrimethylammoniu...

This study refers to the application of in-situ electrochemical synthesis as an alternative method to improve the properties of porous materials against harmful external agents that deteriorate them. It is oriented to an understanding of the effects of crystallisation on the pore structure of different compounds commonly used in the restoration and...

Electroprecipitation can be considered as a novel consolidation technique that can compete with commercial consolidation treatments since, it allows to reduce its accessible porosity, both superficially and in-depth; increasing considerably its mechanical properties and precipitating a compound chemically compatible with the material to be treated....

This research presents a novel approach based on the combination of nanotechnology and Roman technology by investigating how adding nanoCa(OH)2 and nanoSiO2 modify the performance of air lime mortars containing Roman ceramics. Microstructural, physico-mechanical properties were periodically controlled until 120 days of curing. XRD and TGA analyses...

The evaluation of the antifungal activity of Mg(OH)2 and Ca(OH)2 nanoparticles (NPs), synthesized by sol–gel method and their mixtures at different concentrations, is reported. The antifungal activity of the hydroxide NPs was studied using Aspergillus niger and Penicillium oxalicum isolated from stone surfaces. These model organisms were selected d...

This study presents a correlation between microstructure, atomic scale observations and intrinsic cathodoluminescence emission from two types of brucite (Mg(OH)2) nanoparticles synthesized by hydrothermal and sol-gel methods, and a third one, commercially acquired. It is reported for the first time, the spectral cathodoluminescence (CL) in an Envir...

This study examines crystal development during the carbonation of lime mortars according to the additives used and curing conditions. Two types of samples were prepared, one with sand and the other one additionally including Roman ceramics. These mortars were cured: 1) by spraying with a carbonation accelerator product under laboratory conditions;...

The degradation of stone cultural heritage represents an irreversible loss of rich cultural heritage, and seeking ways to preserve it is urgent. Among different degradation processes, the loss of stone cohesion and biodeterioration are two of the most common issues that affect stone substrates. To solve this, the introduction of nanotechnology in t...

More recently, the biological colonization of stone heritage and consequently its biodeterioration has become the focus of numerous studies. Among all microorganisms, fungi are considered to be one of the most important colonizers and biodegraders on stone materials. This is why the development of new antifungal materials requires immediate action....

In recent times, nanomaterials have been applied in the construction and maintenance of the worldÅLs cultural heritage with the aim of improving the consolidation and protection treatments of damaged stone. These nanomaterials include important advantages that could solve many problems found in the traditional interventions. The present paper aims...

Global climate changes and the aroused environmentally-energy problems categorically moved the research efforts towards programmed processing of a novel class of hierarchical materials having well defined phase, compositional and morphological features. The synthesis based on the principles of the molecular design and integrative chemistry which in...

Micro and nanostructured brucite (Mg(OH2)) particles synthesized by hydrothermal method from solutions with high content of hydrazine (0.14 M) and nitrate (0.24 g) were compared with samples obtained from low hydrazine content (0.0002 M) and nitrate (0.12 g). The samples were heated at 180 °C for 4 h, 6 h and 12 h. XRD, TEM-HRTEM, SAED and image an...

The dehydration process from Mg 0.97Ca0.03 (OH)2 nanoparticles (brucite type hexagonal structure) to Mg0.97Ca0.03 O (periclase type cubic structure) was studied by Transmission Electron Microscopy (TEM-HRTEM), Electron Diffraction (SAED), EELS spectroscopy (EELS) and image analysis. The transformation process was monitored in function of the reacti...

Paper aging and protection are of crucial interest for improving the preservations of library collections and archives. Highly aging-resistant cellulose fiber sheets were obtained by treatment with magnesium hydroxide nanoparticles (Mg(OH)2). The procedure was tested on the sheets made of bleached (B) and refined unbleached (UB) pine cellulose fibe...

Granite is one of the most widely used building stone and is a main component in many heritage buildings for its austere appearance and its availability as a stone of the Earth's crust. When exposed at the Earth's surface, thermal changes are responsible for its decay, especially in granites exposed to weathering. Feldspars, an important component...

This paper analyses the efficacy of dispersions of nanoparticles of calcium hydroxide for consolidating lime mortars, according to three variables: the type of dispersion (3 consolidating compounds—CaLoSil�, Nanorestore� and Merck�—with different-sized calcium hydroxide particles); the concentration of the dispersion (5 and 25 g/L of Ca(OH)2 in iso...

Hierarchically assembled TiO 2 nanoparticles into larger spherical ones were obtained using aerosol-assisted processing method. Unagglomerated particles with the mean size of 440 nm were obtained from colloidal solution of TiO 2 nanoparticles (~4.5 nm) using ultrasonic spray pyrolysis at 550°C. Their morphological complexity and structural polymorp...

In this research, we report the preparation and characterization of SnO2thin films preparation by the Ultrasonic Spray Pyrolysis technique using different fluorine content dissolved in ethanol as precursor solution, for its possible application as TCO's. The structural, optical and electric properties of synthesized SnO2:F films have been character...

Controlled magnesium hydroxide particles were successfully synthesized via a simple hydrothermal method. The influence of temperature and reaction time on the hydrothermal synthesis of Mg(OH)2 was studied. The results provide new parameters to control the morphologies, particle sizes, agglomeration level and crystallographic structures of the bruci...

Sub-micronic particles are of considerable interest for a wide variety of applications, such as catalyst or optical ceramics, due to their unique properties determined by size, composition and structure. In this work, we have reported a simple, rapid, single-step aerosol processing for the continuous synthesis of nanostructured particles having hom...

In this research, we report the preparation and characterization of SnO2 thin films preparation by the Ultrasonic Spray Pyrolysis technique using different fluorine content dissolved in ethanol as precursor solution, for its possible application as TCO´s. The structural, optical and electric properties of synthesized SnO2:F films have been characte...

Mg(OH) 2 nanoparticles has been successfully synthesized by means of the hydrothermal method. The effect of the reaction time and the synthesis temperature on the nanoparticles obtained has also been studied. The physic-chemical properties of the synthesized brucite samples have been characterized by X-Ray-diffraction (XRD), scanning electron micro...

The consolidation effects of portlandite ðCaOHÞ 2 nanoparticles have been determined in carbonate stones (dolostone), typically used in historical buildings from Madrid, Spain, just after 20 days consolidation at 20°C under a dry [33% relative humidity (RH)] and a humid environment (75% RH) and after 18 months under room temperature and humidity co...

The consolidation effectiveness and changes in the petrophysical properties of dolostones, typically used in historical buildings, are studied after one year of their consolidation with a Ca(OH) 2 nanoparticles based product. Dolostone samples were subjected to different accelerated aging tests to simulate the most common outdoor heritage deteriora...

RESUMEN El Paredón de Los Mártires en la ciudad de Tunja – Colombia es una estructura de tapia pisada, declarada como Bien de Interés Cultural Nacional, por contener los vestigios del sacrificio de importantes mártires boyacenses que ofrendaron su vida por la independencia de la República de Colombia. Presenta graves problemas de deterioro que afec...

Non-desalinated and desalinated fragments of Iberian, Italic and Tarraconensian amphorae sherds, found in different underwater marine environments, were compared to determine the decay caused by salt crystallization. Polarizing light and fluorescence optical microscopy, scanning electron microscopy coupled to energy dispersive X-ray spectroscopy, X...

We present here an innovative building technique, which uses ecological, inexpensive and environmentally friendly materials. These compressed earth blocks seem to be very good for building purposes and that is why we have characterized three types of compressed earth blocks (CEB, named by their color as yellow, grey and red) mineralogically by mean...

Scanning-Transmission and Transmission Electron Microscopy techniques (STEM and TEM) have been applied to the characterization of nanostructured gadolinium oxides doped with europium synthesized by spray pyrolysis. The High Angle Annular Dark Field (HAADF) – Scanning Transmission Electron Microscopy (STEM) tools have been used to perform a tomograp...

The defects in calcium carbonate polymorphs forming when portlandite nanocrystals are exposed to high relative humidity were directly observed and analyzed under high-resolution transmission electron microscopy. The findings provided significant insight into aragonite to calcite phase transformation mechanisms. The aragonite lattice exhibited stack...

Spray Pyrolysis (SP) is performed at 700°C in dry air atmosphere using common nitrate aqueous solutions (0,1M) as precursor in order to obtain nanostructured particles with the composition Gd2-xEuxO3 (x= 0.05, 0.10 and 0.30). In this work, three samples with different atomic europium concentration (1, 2 and 6%) were studied. After, the obtained par...

El presente trabajo muestra los resultados obtenidos en el desarrollo de un nuevo método de síntesis de partículas de Gd2O3 dopadas con europio. Esta nueva línea de trabajo consiste en el calentamiento mediante microondas de los reactivos en estado sólido junto a distintos porcentajes (5 y 10% en peso) de carbono activado (añadido para aumentar la...

Calcium hydroxide (also known as lime) is one of the oldest products used in construction, mainly as a binder in mortars (joint mortars, renderings, wall fillings, etc), in mural paintings, as a consolidant product, together with other materials such as rammed-earth. . In Conservation Science it can be used to restore the cohesion loss by filling t...

Aluminum alloy 2014 is used to obtain nanostructured powders via mechanical alloying. The evolution of the diffusion processes is observed by the development of defect structures and nanoprecipitates after 10 h of milling. The characterization includes analytical and high resolution transmission electron microscopy. Dislocations associated with dif...

This article reports on a study of Iberian, Italic and Tarraconensian amphorae sherds found in different underwater marine environments. Non-desalinated fragments were compared to fragments desalinated using the procedure normally applied to underwater archaeological objects to study the efficacy of the method and determine both the state of conser...

The effect of high relative humidity (90% and 75% RH) on phase transformation and stability of CaCO3 polymorphs has been studied based on the structural and morphological changes from a colloidal solution based on Ca(OH)2 nanocrystals. Carbonation process has been confirmed indicating differences in nucleation and stability of CaCO3 polymorphs as a...

The processing of europium-doped gadolinia (Gd2O3:Eu) nanostructured particles has been realized using the bottom-up chemical approaches either by a hot-wall spray pyrolysis technique (SP), starting from the aerosol of common nitrates precursors, or a high energy ball milling (HEBM) of common acetate precursors. The former one yields high-purity na...

There is a wide range of processing methods being applied in nanosynthesis many of them relating to sophisticated chemical aerosol routes for making clusters, nanoparticles or nanostructured materials. The aerosol process involves formation of discrete droplets of precursor solution and control over their thermally induced decomposition and phase t...

In this article, the results of a treatment applied to dolomitic stones using an isopropyl colloidal solution based on calcium hydroxide nanoparticles with a concentration of 2.0g/l are presented. The consolidation process in the stone has been checked before and after 28 days of exposure to 75% relative humidity. Morphologic and structural studies...

A consolidating product based on nanoparticles of slaked lime (Ca(OH)2) dispersed in isopropyl alcohol was exposed under different relative humidities (RH), 33%, 54%, 75% and 90% during 7, 14, 21 and 28 days. The characterization of the calcium hydroxide nanoparticles and the formed calcium carbonate polymorphs have been performed by Micro Raman sp...

A study of the stability of calcium carbonate polymorphs formed as a result of the carbonation process from an alcoholic colloidal solution of nanocrystals of Ca(OH)2 in low relative humidity (RH) conditions (33% and 54% RH) is presented in this research. The crystalline behavior, the time dependence of nucleation and the phases’ transformations as...

Nanoscience deals with a large diversity of research fields and applications due to in the nanomaterials most of their properties are modified or improved by the effect of the reduction in size. One of the main aspects in conservation of cultural heritage properties is to minimize or repair the decay of stone materials as a result of their exposure...

Red emitting Y2O3:Eu3+ (5 and 10 at.%) submicronic particles were synthesized through ultrasonic spray pyrolysis method from the pure nitrate solutions at 900 °C. The employed synthesis conditions (gradual increase of temperature within triple zone reactor and extended residence time) assured formation of spherical, dense, non-agglomerated particle...

In this study, nanophase, spherical, polycrystalline (Y 1-xGdx)2O3:Eu3+phosphor particles were synthesized from aerosols of corresponding nitrate solutions, ultrasonically generated at 1.3 MHz frequency, and thermally decomposed at 900 and 1100°C. Structural and morphological analyses done by X-ray powder diffraction (XRPD) and transmission electro...

Among the methods currently used for nanophase processing, synthesis through dispersion phase (aerosol) enables generation of ultrafine powders with controlled stoichiometry. It represents a "bottom-up" chemical approach that provides control over a variety of important parameters enabling the formation of either amor-phous, nanocrystalline or meta...

Ultrafine particles or nanoparticles (ranging from a few nanometers to 100 nm) are of considerable interest for a wide variety of applications, ranking from catalyst to luminescence ceramics, due to their unique and improved properties primarily determined by size, composition and structure. This study presents the preparation and characterization...

Slaked lime (Ca(OH)2) nanoparticles were exposed at 33% and 75% relative humidity (RH) to consolidate dolostone samples used in historical buildings. Non-destructive techniques (NDT) were applied to determine the chemical, morphological, physical and hydric properties of the stone samples, before and after 20days treatment. Morphological and minera...

The development of the nanotechnology has contributed to improve the electrochemical properties in rechargeable batteries. The Spray Pyrolysis method allows to obtain nanostructured materials with spherical morphology, narrow particle size distribution and compositional homogeneity. Nanostructured particles have been prepared in this work to be use...

The development of the nanotechnology has contributed to improve the electrochemical properties in rechargeable batteries. The Spray Pyrolysis method allows to obtain nanostructured materials with spherical morphology, narrow particle size distribution and compositional homogeneity. Nanostructured particles have been prepared in this work to be use...

In the field of materials for lithium ion batteries, the lithium iron phosphate LiFePO 4 has been proven for use as a positive electrode due to its good resistance to thermal degradation and overcharge, safety and low cost. The use of nanostructured materials would improve its efficiency. This work shows the results of the synthesis of nanostructur...

Los óxidos de gadolinio y de ytrio dopados con europio (Gd2O3:Eu, Y2O3:Eu) presentan propiedades luminiscentes. Dichas propiedades mejoran con la utilización de materiales nanoestructurados, con geometría esférica y estrecha distribución de tamaño de partícula. Además, las propiedades luminiscentes son favorecidas cuando se tiene una distribución h...

Gadolinium and Ytrium oxides doped with europium (Gd2O3:Eu, Y2O3:Eu) have luminiscent properties. Such properties are improved with the use of nanostructured materials with spherical geometry and narrow particle size distribution. Besides, luminescent properties enhance with a homogeneous distribution of dopant centers in the host matrix material....

Nanometer-sized particles (1–100 nm) are of considerable interest for a wide variety of applications, ranking from catalyst to luminescence ceramics, due to their unique and improved properties primarily determined by size, composition and structure. In this study, we report a simple, rapid aerosol decomposition process for the continuous synthesis...

High purity europium-doped gadolinia (Gd2O3:Eu3+) have been prepared using spray pyrolysis technique yielding nanostructured non-agglomerated particles with spherical morphology. Comparative microstructural analysis was done for different europium concentrations. The particle homogeneity, crystallization and nanostructure development were analyzed...

Gadolinium oxide doped with europium in different atomic proportions (0.09/0.01, 0.08/0.02, 0.07/0.03, 0.06/0.04) was produced by spray pyrolysis. The stoichiometric droplets of aerosol, generated with an ultrasonic device, produced nanoparticles after dehydration, decomposition and a reaction process in a unique step at intermediate temperatures (...

In this paper, the influence of the Eu3+ center concentration on the structural and morphological properties of the Gd2O3 system obtained by Spray Pyrolysis have been studied. The processing route includes aerosol formation by means of ultrasonic device (resonant frequency ranging of 2.1MHz) from common gadolinium and europium nitrate solutions and...

Thermoluminescence signals and morphological studies are reported for a new phosphor of Gd2O3. The phosphor particle material was synthesized by an aerosol technique and it is heavily doped with Eu. Annealing at 1200 °C increases the luminescence efficiency by ~1000-fold relative to the as-prepared material. The emission spectra are primarily from...

Petrology has turned into a fundamental discipline for the step forward in research and conservation of architectural and monumental heritage, in the causes generating its decay, as well as in the most adequate conservation and protection techniques according to materials´ petrophysical characteristics and the type of environment in which materials...

El método de spray pirólisis ha sido utilizado para la obtención de nanomateriales bajo condiciones controladas. Este método ha sido aplicado en la formación de un aerosol mediante ultrasonido a partir de una disolución de los óxidos de Gadolinio y óxidos de Eu y de Oxidos de Ytrio y óxidos de Europio utilizados como materiales de partida para sint...