Javier Garcia-Guinea

The National Museum of Natural Sciences · Geologia

The historical Madrid meteorite chondrite fell in 1896 showing thin melt veins with a 65% of brecciated forsterite fragments surrounded by a fine grained matrix formed by troilite, chromite and Fe-Ni blebs. It exhibits a delicate iron infill, neo-formation of troilite in pockets and shock veins and neo-formation of Na-feldspar formed at high temper...

Fluid inclusions and stable isotopes of giant transparent gypsum crystals in a huge geode recently discovered in Pulpi (SE Spain) are useful tools for explaining its geological formation. Fluid inclusions suggest a mixture of fluids, starting with freshwater and including seawater in more advanced stages of the gypsum crystal growth. The isotopic c...

Arthropod eyes are built of repeating units named ommatidia. Each single ommatidium unit contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The insect Copium eye ommatidia include additional calcium-phosphate deposits, not described in insects to date, which can be examined today using a combined set of modern...

GdAl3(BO3)4:Dy3+, Sm3+, Eu3+, and Tb3+ samples were successfully achieved via a sol-gel combustion method. The observed XRD analysis confirms the formation of the desired GAB host, indicating rhombohedral structures that agree well with JPCD card number 72–1985. The FTIR analyses show the detection of B O stretching and B O B bending modes as we...

GdAl3(BO3)4:Dy3+, Sm3+, Eu3+, and Tb3+ samples were successfully achieved via a sol-gel combustion method. The observed XRD analysis confirms the formation of the desired GAB host, indicating rhombohedral structures that agree well with JPCD card number 72–1985. The FTIR analyses show the detection of B − O stretching and B − O − B bending modes as...

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Fire is a major destructive agent for dimension stone. Practically all historic buildings have suffered one or more fires over the course of their lifespan. There are numerous studies on the effect of fire on stone. Generally speaking, these effects can be divided into aesthetic and structural. Aesthetic effects involve a color shift to reddish hue...

This paper reports on the luminescence characterization of TLD-100 (LiF: Ti, Mg), TLD-200 (CaF2: Dy), TLD-400 (CaF2: Mn) and GR-200 (LiF: Mg, Cu, P) dosimeters exposed to electro beam, beta and ultraviolet C radiation -UVC-. All of them show high sensitivity to radiation regardless of whether it is ionizing or partially ionizing radiation based on...

La Geoda gigante de Pulpí es uno de los hallazgos mineralógicos internacionales más importantes de las últimas décadas. Sus cristales pinacoidales y prismas de yeso de excepcional pureza de hasta dos metros de longitud han despertado el interés tanto de la comunidad científica como del público general. En este trabajo se hace una revisión bibliográ...

The Traspena meteorite fell on 18 January 2021 about 20 km southeast of the city of Lugo (Galiza, Spain), shortly after a huge and bright fireball crossed the sky for 4.84 seconds. Astrometric measurements obtained from the fireball cameras of the Universidade de Santiago de Compostela (USC) as well as from many casual videos were used to determine...

This study reports cathodoluminescence (CL) and photoluminescence (PL) properties of undoped borate Ca3Y2B4O12 and Ca3Y2B4O12:x Dy3+ (x = 0.5, 1, 2, 3, 5, and 7) synthesized by gel combustion method. Micro-X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), CL and PL under electron beam and 359 nm pulse laser excitation, respec...

A series of Y1-xAl3(BO3)4:x Tb³⁺ (x = 0.5 to 7 wt%) phosphors synthesized by a gel combustion method have been systemically investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), energy dispersive spectroscopy (EDS), and photoluminescence (PL) as a function of temperature from 300 K to 10 K and 300 K–550 K. An XRD analysis conf...

Thermoluminescence (TL) emission of tridymite, a quartz-like mineral, could be used for a variety purposes, including basic research, ceramic technology, traditional/medical industry, and dating. The current study focused on the investigation of the thermal effects on both the luminescence emission and structural properties of natural tridymite. Th...

We herein report on the radiation effect on the red thermoluminescence (TL) emission of synthetic Al 2 O 3 :C (commercial TLD-500 supplied by Harshaw) and Al 2 O 3 :Cr,Ni (grown by the Verneuil method). The materials were previously characterized by cathodoluminescence (CL), displaying significant differences in the UV-IR spectral emission range re...

Preparation and synthesis of luminescent materials has a special interest in medicine, industry and research due to the wide variety of applications offered by phosphors. In this study, pellets of a mixture of CaF2 and Tm2O3 which were pressed and thermally treated up to 600 ºC were prepared in air. Combined SEM (scanning electron microscopy), EDX...

RESUMEN.‐ El presente catálogo recoge imágenes en color escaneadas directamente de 329 placas de tamaños iguales de 21x21 cm de la colección de mármoles históricos de España patrocinada por los reyes de España desde 1700 a 1808 perteneciente a la Colección de Geología del Museo Nacional de Ciencias Naturales de Madrid (MNCN, CSIC). Se incluyen las...

In this study, we report a detailed analysis of the photoluminescence (PL) and cathodoluminescence (CL) properties of La2CaB10O19 (LCB) doped with Dy ion.. Dy doped LCB materials were successfully synthesized using a sol-gel combustion method. Dy doped LCB has the monoclinic structure with lattice parameters a = 11.02067 Å, b = 6.55755 Å, c = 9.105...

Here we report a detailed structural analysis, and properties of the cathodoluminescence (CL), photoluminescence (PL) and 3D thermoluminescence spectra of the Tm³⁺ incorporated ZnB2O4 phosphor successfully synthesized through wet-chemical synthesis. The formation of a single-phase compound is verified through X-ray diffraction (XRD) studies. The ph...

La2MoO6 orange-red phosphors with high efficiency incorporated with Eu, Dy and Sm have been synthesized through a gel combustion method. The influences of rare earth doping in synthesized samples were analysed by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and cathodoluminescence. Rare earth doped...

It is widely accepted that metamorphism induces a remobilization of iron sulfides, sweeping away original ones while creating new ones. This paper analyzes size distributions of iron sulfides in several samples from the Caples and Torlesse terranes from the Otago Schist (New Zealand) using high-resolution X-ray computed tomography, which allows all...

We report narrow-band green-red emitting Mg2SiO4 phosphors successfully synthesized through solid-state reaction method, and the cathodoluminescence (CL) and photoluminescence (PL) properties of the samples were investigated in detail. Under electron beam and 275 nm excitation, Mg2SiO4 phosphors doped with various Eu3+ and Tb3+ concentrations in th...

Thallium (Tl) is a hazardous trace metal that can harm human and environmental health. Tl pollution can result from the mining and smelting of Tl-bearing minerals, but also the natural weathering of Tl-bearing sulfide minerals may induce Tl release to the environment. In this study, hydrothermal deposits hosted in dolostone rocks sited along fossil...

A platina sample brought to Spain in the last quarter of the 18th century is nowadays exhibited at the National Museum of Natural Sciences in Madrid. It originated from the ancient Mineralogical Museum of the School of Applied Chemistry at El Turco Street in Madrid and most probably corresponds to the material used by François Chabaneau for his exp...

This paper reports on the cathodoluminescence (CL) emission of kamphaugite-(Y) (CaY(CO3)2(OH)·H2O) and kristiansenite [Ca2ScSn(Si2O7)(Si2O6OH)] that display very complex spectra. The carbonate sample, growing in spheres no longer than 3 mm, contains signiicant concentrations of REE giving rise to sharp and narrow wavebands peaked at 312, 486, 546,...

The 400 nm-thermoluminescence (TL) emission of UV (254.7 nm) irradiated Ca-rich carbonates of inorganic (aragonite) and biogenic (mollusc exoskeleton) origin is here reported. The samples exhibit complex glow curves, but (i) acceptable TL sensitivity when exposed to ultraviolet C (UVC) irradiation and (ii) stability of the UV-induced TL signal with...

The Cangas de Onís regolith breccia is an H5-H6 ordinary chondrite that fell to Earth in 1866. It is constituted by 60% H6-H5 clasts within an H5 clastic matrix. All clasts are affected by intense fissuration, with an intricate pattern filled by kamacite and troilite, shock metamorphism of plagioclase into maskelynite. The chondrite is composed of...

This paper reports on the thermoluminescence (TL) emission (from 250 to 500 nm) of a 10 Gy irradiated natural Na-rich aluminosilicate from Minas Gerais (Brazil), previously characterized by Raman spectroscopy and differential thermal analysis techniques. 3D-TL spectrum of the analyzed sample displays a complex glow curves with five different emissi...

The Lesvos Petrified Forest was formed by silicification process of plants during the Lower Miocene era, when intense volcanic activity occurred in that region. It is situated in the western part of Lesvos island (NE Greece) and consists of hundreds of standing and lying fossilized tree trunks, covering an area of 150 km 2. It is one of the most im...

The Lesvos Petrified Forest was formed by silicification process of plants during the Lower Miocene era, when intense volcanic activity occurred in that region. It is situated in the western part of Lesvos Island (NE Greece) and consists of hundreds of standing and lying fossilized tree trunks, covering an area of 150 km 2. It is one of the most im...

This work reports on the cathodoluminescence (CL) and thermoluminescence (TL) properties of gem-quality diaspore samples from Milas/Muğla (Turkey) after 100 h of ultraviolet-C (UVC) exposure. The UVC exposure induces significant changes in the intensity of the CL emission in the range of 400–800 nm that would be mainly associated with photo-oxidati...

In present work, a series of Eu doped zinc borate, ZnB2O4, phosphors prepared via wet chemical synthesis and their structural, surface morphology, cathodoluminescence (CL) and thermoluminescence (TL) properties have been studied. Phase purity and crystal structure of as-prepared samples are confirmed by X-ray diffraction measurements (XRD) and they...

The radiation effect of the luminescence emission of Ca-rich oxalate biogenic materials (gallbladder and renal calculi) and a commercial standard sample (CaC2O4·H2O) is here reported. The samples, previously characterized by means of environmental scanning electron microscope, energy dispersive X-Ray spectroscopy, thermogravimetric and differential...

Spectral emission of a natural layered double hydroxide (LDH) studied by cathodo-and photoluminescence (PL), displays complex glow curves with wavebands that could be attributable to (i) the paramagnetic Non-bridging Oxygen Hole Center defects (peaked at 330 nm), (ii) F o centers (oxygen vacancies trapping two electrons) associated with O vacancy-h...

Tridymite exhibits a complex 400 nm-induced thermoluminescence spectra consisting of five groups of components at (i) 90 and 130 oC (due mainly to oxygen vacancies, substitution and interstitial atoms and/or impurities that create localized charge losses), (ii) 200 oC (linked to a partial phase transition), (iii) 230 oC (associated probably with al...

Modern cathodoluminescence detectors coupled to Environmental Scanning Electron Microscopes (ESEM) with X-ray microanalysis are increasingly sensitive and, nowadays, low intense luminescence spectra may be recorded from nominally non-luminescent solid materials. Structural or attached hydroxyl groups are universally present in solid samples kept in...

Undoped and Pr, Sm and Tb activated BaAl2O4 phosphors have been synthesized by solid state reaction method and combustion method. The structure and morphological observation of the phosphor samples were monitored by X-ray powder diffraction (XRD) and environmental scanning electron microscope (ESEM) coupled to an energy dispersive X-ray spectromete...

Layered double hydroxides (LDHs) and many of the related hydrotalcite-like minerals have been well studied from the chemical and structural point of view; however, their luminescence properties have been scarcely studied. We herein report on the thermoluminescence (TL) behaviour of a natural LDH (Mg6Cr2CO3(OH)16·4H2O), previously characterized by X...

This paper presents an experiment on lampenflora removal in show caves located in a tropical monsoon climate in southeast Asia. Lampenflora thrive in wet conditions on surfaces directly illuminated by white light. They colonize different levels in show caves, from the cave ceiling, with a biota characterized of mainly cyanobacteria (Oscillatoria, S...

In this study, ZnB2O4:xSm3+ (0.01 ≤ x ≤ 0.05 mol) powder phosphors have been synthesized by low temperature chemical synthesis method. The structure and morphological observation of the phosphor samples were systematically monitored by X-ray powder diffraction (XRD) and environmental scanning electron microscope (ESEM) coupled to an energy dispersi...

INFORMACIÓN DEL VÍDEO Canal: GEOLOGIA EN EL CAMPO Hora de la subida: 4 de February de 2018, 12:48 Duración:7:29 Archivo sin procesar: ROCAS. Tipos de Rocas.mp4 URL del vídeo: https://youtu.be/DPR2nC6Feas RESUMEN. Las ROCAS son los materiales que forman la Geosfera. Están constituidas por minerales. Pueden estar formadas por un único tipo de minera...

Cathodo- and thermoluminescence emission of calcium phosphates, synthetized by chemical precipitation and characterized by X-ray diffraction, environmental scanning electronic microscopy and energy dispersive spectroscopy have been studied. Thermal treatment at 1100°C increases the crystallinity, a phase transition (hydroxylapatite + β-tricalcium p...

En los DESIERTOS las precipitaciones son reducidas. Tienen vida escasa dependiendo del tipo de desierto. La vegetación se adapta a la humedad existente y la fauna usualmente se esconde durante el día. Forman la zona más extensa de la superficie terrestre: con más de 50 millones de kilómetros cuadrados, ocupan casi un tercio de esta. De este total,...

Hydrothermal pyrite is an important source of thallium (Tl) but this rare element can be also detected in the secondary iron goethite-lepidocrocite and jarosite ores, associated to hydrothermal kerogen, manganese oxides, accessorial potassium minerals and tiny Tl-bearing clusters shielded in quartz masses. We studied Tl-bearing samples collected fr...

In this study, air, water, and host rock in show caves in a Vietnam’s karst region was monitored and analyzed to identify the ventilation regime and track the cave air CO2 sources. In general, the studied caves are well ventilated. In dynamic – multiple entrance caves, air ventilation is described with the use of U shape model. In static – single e...

Tridymite (one of the important form of silica) is usually employed for (i) industrial purposes such as refractory products as roof construction, lining in equipment, hot stove utilities and coke ovens etc. due to its chemical resistance to high-temperature environments, (ii) in basic research, for the detection of structural changes in different m...

Manganese (Mn) doping of ZnS phosphors was achieved by precipitation method using different ultrasound (US) maturation times. The structural and luminescence properties of the samples were carried out by means of X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), photoluminescence (PL), and cathodolum...

The aim of this study is to calculate the thermoluminescence kinetic parameters of beta irradiated natural tridymite mineral which has a complex multitrap system. The glow curve corresponding to 2.4 Gy shows five maxima peaked respectively at 90, 126 oC, and three less intense overlapped maxima at higher temperatures, which are 187, 225 and 320 oC....

A series of novel apatite-based Ca2Y8(SiO4)6O2 phosphors doped with Ce(3+) and Tb(3+) were synthesized by a solid-state reaction method at different calcination temperatures and times. The comparative results of thermal analysis (TG-DTA), FTIR, X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) reveal that the firing temp...

This paper reports on the cathodoluminescence (CL) emission of both natural and synthetic lanthanide-rich phosphates (Ln³⁺: Ce, Nd) previously characterized by X-ray Diffraction (XRD), Environmental Scanning Electronic Microscopy (ESEM) and Energy Dispersive Spectroscopy. The thermal treatment at 700 °C performed on the synthetic sample obtained by...

As known, the luminescence emission of mineral phases could be potentially employed for dosimetric purposes in the case of radiological terrorism or radiation accident where conventional monitoring is not available. In this sense, this paper reports on the thermo- (TL) and cathodoluminescence (CL) emission of both biogenic (common periwinkle – litt...

Several ZnB2O4 powder samples having dopants concentrations of 0.1, 0.01, 0.04 wt% Ce and La were prepared using the nitric acid method via the starting oxides. Several complementary methods such as powder X-ray diffraction (XRD), thermal analyses environmental scanning electron microscopy (ESEM), Radioluminescence (RL) and Cathodoluminescence (CL)...

Abstract We have synthesized powder samples of Dy3+ doped zinc borates by nitric acid method. X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) techniques were utilized to examine the structure and morphological observation of the samples. Luminescence characteristics of the samples were investigated using room temperatu...

Optical measurements of microscale crystals suggest a new model for the luminescence centers associated with classic spectral cathodoluminescence emissions, which has implications for their material and photonic properties. In particular, manganese impurities in aluminosilicate lattices are commonly associated with ultraviolet and green (UV&G) spec...

In the frame of a research project on microscopic distribution and speciation of geogenic thallium (Tl) from contaminated mine soils, Tl-bearing pyrite ore samples from Riotinto mining district (Huelva, SW Spain) were experimentally fired to simulate a roasting process. Concentration and volatility behavior of Tl and other toxic heavy metals was de...

s Ce doped Yttrium aluminate modified by replacing different molar part of aluminium or gallium (Y3Al5−xGaxO12) and Yttrium silicate phosphors activated with Ce and Tb (Y2SiO5:Ce³⁺,Tb³⁺) were synthesized by solid state reaction and a gel combustion method, respectively. X-ray diffraction and Scanning electron microscope (SEM) techniques are used to...

Knowledge of the precise human biomineral composition may allow physicians to recommend an appropriate prophylactic therapy for the patient and thus prevent or delay the stone recurrence. The present study focuses on the application of complementary analytical techniques to the characterization of human urinary stones. Several gallbladder and renal...

The inclusion of Zn in insect mandibles affects their hardness and is functional to their use during feeding or reproducing. However, little is known on the chemical/structural base of Zn enrichment. Here, we found that cathodoluminescence (CL) technique revealed two different types of CL spectra in the mandibles of Hymenoptera, depending on the Zn...

Un gran ópalo noble de 33 gramos engastado en montura de plata dorada está expuesto al público en el Museo Nacional de Ciencias Naturales (MNCN). Esta pieza histórica está documentada en su propia montura (año 1772), en el legajo 775 del Archivo del Museo y en la muestra 395 del Catálogo de muestras de Pedro Franco Dávila. Su patrón de difracción d...

The thermoluminescence behavior of long-range ordered crystals is usually explained by the band structure model, using first- and second-order kinetics. However, feldspars have order-disorder phenomena and twinning, and consequently these mathematical descriptions are not helpful in most cases. In this work, the thermally stimulated intrinsic blue...

Pumiceis a natural Si-rich material displaying a complex cathodo- (CL) and thermoluminescence (TL) glow curves. The UV-IR CL emission consists of (i) a UV waveband in the range of 340-420 nm,(ii) blue band at 450-480 nmand (iii) a broad emission in the green-red region (at 550-650 nm)that could be respectively linked to (Non Bridging Oxygen Hole Ce...

Mn-doped CaB4O7 is prepared from aqueous solutions of CaCl2, boric acid, and MnCl2 (20 °C, 3 h).

One hundred and sixty five years ago, Henry Clifton Sorby developed a revolutionary technique to prepare thin and polished sections of rocks and minerals to be observed by transmission and reflectance in the optical polarized light microscopes. Nowadays, Sorby’s methods are still employed for near all inorganic materials with scarce modifications....