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We herein report on the radiation effect on the red thermoluminescence (TL) emission of synthetic Al2O3:C (commercial TLD-500 supplied by Harshaw) and Al2O3: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 related to the presence of dopants. Whilst the CL curve of C-doped alumina exhibits four wavebands peaked at 325 (due to F+ centers) 411 (F centers), 648 (Fe3+) and 785 nm (Ti3+), the Al2O3:Cr,Ni sample shows a narrow, sharp, high intensity maximum at 692 nm with two vibronic side bands of lower intensity at 679 nm and 713 nm attributed to the R-lines of Cr3+. The red TL emission at 650 nm of both materials indicates that they could potentially be used as dosimeters since (i) are sensitive to ionizing radiation at doses over 10 mGy; (ii) show a linear dose response in the range of 10–100 mGy with regression coefficients of 0.999 and (iii) can be reusable with negligible variation in the intensity (never higher than±0.8%) and no observed changes in the shape of the TL curves. The red glow emission intensity corresponding to the C-doped sample hardly changes with the storage time, however Al2O3:Cr,Ni fades significantly (ca 70%), up to ~700 h of storage following a behavior that can be fitted to a decreasing exponential function. Tmax-Tstop test suggests the coexistence of continuous and discrete trap systems in both compounds., This work has been partially funded by CIEMAT, SPAIN (internal project 273-Dosimetria Retrospectiva), Spain.

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 °C were prepared in air. Combined SEM (scanning electron microscopy), EDX (energy dispersive X-ray analysis) and CL-RGB (cathodoluminescence red-green-blue) microanalysis and, complementarily spectral CL analysis of this phosphor were performed. EDX analysis showed that the activator was homogeneously distributed in the prepared specimens. The additional CL emission can be attributed to the properties of some luminescent centers that were apparently created during the annealing. In addition, it seems that other trapping centers were created by new structural defects during the preparation process in the CaF2 lattice. The combined techniques SEM/EDX/CL-RGB have confirmed their capabilities in the characterization of the prepared materials. This contribution provides a process and characterization methods used in the fabrication and characterization of a phosphor that can also be used to optimize the luminescent emission of other similar synthetic materials with rare earth oxides as activators., This work has been partially supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under Grant FIS2015-64793-C02.

This contribution describes a kinetic model attempting to reproduce the response of the thermoluminescent material LiF:Mg,Cu,P when it is irradiated to absorbed dose values in the kGy range. The modelling is based on the hypothesis of a relationship between the irradiation time (i.e. the absorbed dose) and the density of trapping/recombination centres. X-ray diffraction and thermal X-ray diffraction measurements have been performed to investigate the potential radiation and thermal damage on the structure of the material, including the possibility of partial phases. The proposed kinetic model qualitatively reproduces the observed changes in the TL glow curve for temperatures above the main peak as well as the two observed regions of absorbed dose response: linear and sub-linear.

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 initial rapid decay (ca. 70% for the aragonite and 40% for the biogenic carbonate) while maintaining the stability from 75 and 150 h onwards. The dose response shows a signifi cant scattered behavior up to 8 h of UVC exposure, which may be associated with a combination of the phototransfer TL mechanism, the bleaching process, and the partially ionizing effect of the UVC irradiation., Cecilia Boronat thanks the "Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid" and "Fondo Social Europeo" for the support provided under the "Operativo de Empleo Juvenil y la Iniciativa de Empleo Juvenil (YEI)" program (B.O.C.M. Núm.152. Orden 1880/2015, de 16 de junio del 2015).

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 emissions bands peaked at 290, 380, 420, 460 and 500 nm that could be associated with structural and point defects. The UV-blue emission bands have the following characteristics: (i) the 290 nm waveband could be due to defects-sites by the presence of Na ions; (ii) the 380 nm band, caused by intrinsic defects in the lattice (i.e. Non-Bridging Oxygen Hole Centers (NBOHCs), [AlO] centres, alkali planar defects and Oxygen Defect Centers (ODCs), among others); (iii) the 420 nm waveband, linked to the recombination on a centre formed from a hole-oxygen atom adjacent to two aluminum atoms (Al-O-Al) and Al-O-Si complexes; (iv) the 460 nm band, associated with the presence of Ti in the plagiclase crystal lattice. The green waveband could be linked to de-excitation of Mn ions. The estimation of the activation energy (E) from the 10 Gy-induced TL glow curves analyzed by means of the initial rise method display linear regressions with acceptable r coefficients (r > 0.977) that reveal three groups of components with traps at different depth in the crystal lattice of the albite with Ea values in the range of 0.5–0.64 eV., Cecilia Boronat thanks to "Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid, Spain” and "Fondo Social Europeo, Belgium” (PEJ15/BIO/AI-0418) for the support provided under the “Operativo de Empleo Juvenil y la Iniciativa de Empleo Juvenil (YEI)” program (B.O.C.M. Núm.152. Orden 1880/2015, de 16 de junio del 2015).

This work presents the characterization of the thermoluminescence (TL) glow curve of a copper and silver doped lithium tetraborate (Li2B4O7:Cu,Ag) made using three different methods to identify the number of peaks, the trap structure and the kinetics parameters: TM-Tstop, glow curve fitting (GCF) and various heating rates (VHR). The obtained results can be consistently explained assuming four TL glow peaks in the region 50 - 270 °C, originated by a complex trap structure: continuous energy distributions for peaks I, III and IV, and general order kinetics (GOK) discrete trapping level for peak II. Quite similar activation energy values have been obtained by GCF and VHR methods.

This contribution describes a dry physical process to increase luminescence of a mixture of calcium fluoride (CaF2) and thulium oxide (Tm2O3) pellets. Thermoluminescence (TL) technique has been used by means of two different filters (UV-blue and green) for the prepared aliquots irradiated with a 90Sr beta source (10 mGy/s). Many trapping centers were created during the preparation due to new structural defects in the CaF2 matrix, exhibiting a second maximum at 195 °C in the TL glow curve, and having fading of 11% after 1-month storage. Regarding the glow curve structure, first-order kinetics has been reported with a peak-I, around 130 °C, with an activation energy of 1.27(1) eV obtained by the initial rise method using a heating rate of 5 °C/s. Linearity property has been confirmed in the range from 0.1 Gy up to 2.0 Gy. UV-blue TL glow curve shown some changes when a lower heating rate (2 °C/s) was used. Peaks with greater intensity in a factor about 5%, and peaks position at lower temperatures (around 115 °C and 180 °C) were obtained. The results show that this low-cost phosphor can be used at doses higher than 10 mGy, such as in medical and industrial applications. The preparation process parameters used to produce this material are provided.

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) Fo centers (oxygen vacancies trapping two electrons) associated with O vacancy-hole centers and Me–O bonding defects and dehydroxylation process (in the range of 360–500 nm), (iii) presence of Mn2+ (0.15%) substituting Mg2+ ions (530–640 nm) and (iv) a red-IR band mainly associated with Cr and Fe point defects. The presence of Cr3+ ion activators induces characteristic PL emission peaks in the red-infrared region at 681, 688 and 696 nm linked to 2E → 4A2 transitions. The sample (Mg6Cr2CO3(OH)16·4H2O) previously characterized by environmental scanning electron microscope, X-ray diffraction, and X-ray fluorescence indicates that this natural hydrotalcite-like compound is associated with hydroxyl-rich silicates (nimite and clinochlore) and Mg-Fe carbonate and Ni-Fe carbonate LDH (pyroaurite and reevesite)., This work was partially supported by the project CICYTCGL2010-17108.

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-ray fluorescence, X-ray energy-dispersive spectrometry, electron probe microanalysis, thermogravimetry and differential thermal analysis, that exhibited a very complex green-IR spectral emission. The broad waveband peaked at ~ 640 nm can be mainly linked to the 4T1 → 6A1 (at 570 nm), 4A2g → 2Eg (~ 685 nm), 4T1 → 6A1 (~ 700 nm), and 1T2g → 3A2g (green) and 1T2g → 3T2g (red) transitions due, respectively, to the presence of Mn2+, Cr3+, Fe2+ and Ni2+. The weak red-TL emission can likely be attributed to the quenching effect due to Fe (~ 8–11%) ions substituting for Mg2+., This work was partially supported by the Project CICYT CGL2010-17108.

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-oxidation processes of the impurities (Cr3+, Ti3+, Fe2+) that substitute for Al3+ in the diaspore (α-AlOOH) lattice. The UVC effect on the 400 nm-TL behavior of beta irradiated samples in the range of 0.1–8 Gy modifies the TL glow curves probably due to both photo-transfer process where electrons release from deeper to shallower traps and redox reactions involving, also, breakages-linkages of chemical bonds. Meanwhile, the ‘as received’ samples consist of three maxima centered at about 120, 180, and 234 °C, the 100 h UVC-irradiated samples display three maxima at 122, 220 and 270 °C. The physical trapping parameters (intensity and peak position, trap depth and pre-exponential factor) for each TL curve were estimated by using a computerized glow curve analysis program., Dr. Mustafa Topaksu acknowledges support by the Research Fund of the Çukurova University through FBI-2017-7569 Project. Cecilia Boronat thanks to “Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid, Spain” and “Fondo Social Europeo, Belgium” (PEJ15/BIO/AI-0418) for the support provided under the “Operativo de Empleo Juvenil y la Iniciativa de Empleo Juvenil (YEI)” program (B.O.C.M. Núm.152. Orden 1880/2015, de 16 de junio del 2015)

Tridymite exhibits a complex 400 nm-induced thermoluminescence spectra consisting offive groups of components at (i) 90 and 130°C (due mainly to oxygen vacancies, substitution and interstitial atoms and/or impurities that create localized charge losses), (ii) 200°C (linked to a partial phase transition), (iii) 230°C (associated probably with alkali ions moving away from Al that leads to [AlO 4 ]° hole-like or [GeO 4 /Li]° centers) and (iv) 320°C (caused by both phase transition and electron recombination with the unstable holes trapped at oxygen vacancies next to Al sites). The application of the T m –T stop protocol confirms a continuum in the trap structure not only because of the successive shifting of the maxima with the increase of the temperature, but also with the enhancement of the activation energy values that have been assessed by means of the initial rise method., S. B. Y. acknowledges support by the Research Fund of the Çukurova University through the [FDK-2016-6178] Pro- ject. C. B. thanks to‘Consejería de Educación, Juventud y Deporte, Comunidad de Madrid Deporte de la Comunidad de Madrid, Spain’and‘Fondo Social Europeo, Belgium’(PEJ15/BIO/AI-0418) for the support provided under the ‘Operativo de Empleo Juvenil y la Iniciativa de Empleo Juvenil (YEI)’program (B.O.C.M. Núm.152. Orden 1880/ 2015, de 16 de junio del 2015)

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 phosphate → β-tricalcium phosphate) and an enhancement of the luminescence emission. Cathodoluminescence and thermoluminescence display a very complex spectra in the UV–IR range where the wavebands would be associated with the presence of (i) hydroxyl groups, (ii) nonbridging oxygen hole centers, (iii) excited oxygens, (iv) peroxy groups, and (v) residual iron ions in the lattice., A. Barrera-Villatoro thanks to UMSNH through the coordination of scientific research coordination CIC-UMSNH 12937 and to CONACYT under research project 177912 and 223069 for their support. C. Boronat thanks to “Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid, Spain” and “Fondo Social Europeo, Belgium” (PEJ15/BIO/AI-0418) for the support provided under the “Operativo de Empleo Juvenil y la Iniciativa de Empleo Juvenil (YEI)” program (B.O.C.M. Núm.152. Orden 1880/2015, de 16 de junio del 2015).

The radiation effect of luminescence emission of Ca‐rich oxalate biogenic materials (gallbladder and renal calculi) and a commercial standard sample (CaC2O4·H2O) is reported. The samples were characterized by environmental scanning electron microscopy, energy dispersive X‐ray spectroscopy, thermogravimetric and differential thermal analyses, display complex cathodoluminescence (CL) and thermoluminescence (TL) glow emissions. CL spectra (in the UV−infrared range) displayed non‐well defined peaks, and exhibited emission at: (i) higher energies (300–490 nm) mainly associated with non‐bridging oxygen hole centers, oxygen‐deficient centers and peroxy intrinsic defects, regardless of the sample; and (ii) higher, narrow and sharp wavebands, in the red region, probably induced by the presence of traces of Sm3+ (4G5/2→6H9/2 transition) and/or Tb3+ (5D4→7F3 transition) only for mineral‐like materials in the human body. The UV‐blue TL emission showed low‐intensity maxima in which it was possible to distinguish at least four groups of components in each sample., Cecilia Boronat thanks ‘Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid, Spain’ and ‘Fondo Social Europeo, Belgium’ (PEJ15/BIO/AI‐0418) for the support provided under the ‘Operativo de Empleo Juvenil y la Iniciativa de Empleo Juvenil (YEI)’ program (B.O.C.M. Núm.152. Orden 1880/2015, de 16 de junio del 2015).

This paper reports on the thermoluminescence and cathodoluminescence behaviour of a well-characterized sepiolite (Si12Mg8O30(OH)4(OH2)4·8H2O). Both natural and induced thermoluminescence curves display a complex emission suggesting a continuum in the trap distribution involving multiorder kinetics. UV¿IR cathodoluminescence spectral emission shows five wavebands at 330, 400 and 440 (associated with structural defects, [AlO4] or non-bridging oxygen hole centers) and 520 and 770 nm (linked to point defects). This daily-use material, that is of interest since could be employed for personal dosimetry in the case of radiation accident or radiological terrorism where conventional monitoring has not been established, were never investigated before.

Luminescence emission from rare earth (REE) ions doped materials are being of interest since can be employed as scintillators, catalysts, battery and magnetic materials, etc. We herein report on the preliminary results obtained from the cathodoluminescence (CL) properties of undoped LaAlO (LAO) and LaAlO: REE (REE=Dy, Pr and Eu) samples synthesized by a sol-gel process based on the Pechini's method with a spray-drying technique. The samples, previously characterized by means of Environmental Scanning Electron Microscopy and Energy Dispersive X-Ray Analysis Spectrometry, display CL spectra with well-defined peaks that could specifically be associated with the LAO structure (in the range of 300–450 nm) and point defects (from 450 to 800 nm) spectral regions. The observed wavebands are as follows: (i) 480 and 570 from the Dy-doped LAO correspond respectively to F→H and F→H transitions, (ii) 490–638 from the Pr-doped LAO is linked to P→H, D→H transitions and (iii) 590 and 620 where the dopant Eu gives rise to D→F and D→F transitions and (iv) a UV-blue broad band is associated with NBHOC in undoped LAO. Such emissions are due to the presence of the 4f electrons of rare earth ions that are shielded by the outer 5s and 5p electrons, the intra-4f emission spectra of REE that induce sharp and narrow wavebands., >Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid, Spain”, >Fondo Social Europeo, Belgium” (PEJ15/BIO/AI-0418) for the support provided under the “Operativo de Empleo Juvenil y la Iniciativa de Empleo Juvenil (YEI)” program (B.O.C.M. Núm.152. Orden 1880/2015, de 16 de junio del 2015).

Pumice is 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 nm and (iii) a broad emission in the green-red region (at 550–650 nm) that could be respectively linked to Non Bridging Oxygen Hole Centers ([tbnd]Si–O•), self-trapped excitons and point defects (Mn −0.03%- and Fe −1.15%-). Thermal treatments performed on the TL glow curves allowed us to determine that the trap system could be associated with a continuum in the trap distribution, since successive thermal pretreatments in the range of 200–310 °C induce an emission that shifts linearly to higher temperatures when the thermal pretreatment (T) is increased, while the intensity of the maxima decreases similarly to the peak area. The evaluation of the Ea values, s value and the trap system calculated by VHR, IR and Glow curve fitting methods considering three possible distribution function for n(E): gaussian, exponential and uniform, has given matching values for the 280 °C TL peak.

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) spectral cathodoluminescence (CL) emissions peaked at circa 280–290 nm and 550–570 nm. These UV&G emissions from insulator solids, composed of different metals, increase with the presence of hydroxyl groups by water dissociation, or hydro-peroxide decomposition, under ionizing or UV radiation exposure. The UV&G bands are found to be associated with surfaces of insulator solids as electron beams affecting only the external surface region –microns deep– of the samples. Since massive ice (HO at −10 °C) shows CL without UV&G bands, the origin must lie within hydroxyl groups in the chamber of the environmental scanning electron microscope that couple to surface metals. The increase of UV&G signals in insulator solids, including hydrothermal feldspars, low crystalline silica or synthetic SiO among others is commonly observed in samples after energetic hydrous treatments, The proposed mechanism consists of a nonspecific reaction electron-beam + 2 (Metal-OH) > HO + O + photons, that agrees with radiolytic models but not with ligand field theory. Knowledge of this process might be useful to evaluate geological samples for dosimetry or dating purposes employing luminescence techniques., This work was supported by the Spanish Ministry of Economy and Competitiveness under the research projects CTM2014-55321 and MAT2015-64110-02-1-P.

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 – littorina littorera – shell made of calcite 90% and aragonite 10%) and inorganic (aragonite 100%) Ca-rich carbonates previously characterized by X-ray diffraction and Raman spectroscopy. Whereas the aragonite sample displays the main CL waveband peaked in the red region (linked to point defects), the more intense emission obtained from the common periwinkle shell appears at higher energies (mainly associated with structural defects). The UV-blue TL emission of the samples, regardless of the origin, displays (i) an acceptable ionizing radiation sensitivity, (ii) linear dose response in the range of interest (up to 8 Gy), (iii) reasonable stability of the TL signal after 700 h of storage with an initial decay of ca. 88% for the mineral sample and 60% for the biogenic sample and maintaining the stability from 150 h onwards. (iv) The tests of thermal stability of the TL emission performed in the range of 180–320 °C confirm a continuum in the trap system., Cecilia Boronat thanks to “Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid, Spain” and ”Fondo Social Europeo, Belgium” (PEJ15/BIO/AI-0418) for the support provided under the “Operativo de Empleo Juvenil y la Iniciativa de Empleo Juvenil (YEI)” program (B.O.C.M. Núm.152. Orden 1880/2015, de 16 de junio del 2015).

Three zaratite samples from Cape Ortegal (type locality, Spain), Texas, Lancaster County (Pennsylvania) and Heazlewood (Tasmania) were analyzed by electron-probe micro-analysis (EPMA), environmental scanning electron microscopy with energy-dispersive spectrometer (ESEM-EDS), X-ray diffraction (XRD), differential thermal analysis and thermogravimetry (DTA-TG), micro-Raman and Fourier-transform infrared spectrometry (FTIR). The empirical formulae calculated from EPMA exhibit different molar ratios (Ni/CO3, Ni/OH and H 2 O/Ni), showing that these three samples referred to as ‘zaratite’ are chemically distinct; they are actually close to either anhydrous zaratite (Ortegal), nullaginite (Tasmania) or gaspeite (Pennsylvania). The XRD patterns of the three samples only validate their low-crystallinity character with variable mineral inclusions. Raman and FTIR spectra confirm large similarities among the three samples, in line with the general chemical kinship of these nickel hydroxycarbonate (± hydrate) materials. Our data suggest that the natural nickel hydroxycarbonate materials, collectively referred to as ‘zaratite’ on the basis of colour, occurrence and poor crystallinity, are in fact so diverse in terms of Ni/C/H ratios that the ‘zaratite’ term should not deserve a species status and so remains highly questionable.

The luminescence (cathodoluminescence and thermoluminescence) properties of natural bones (Siberian mammoth and adult elephant), commercial hydroxyapatite and collagen were analyzed. Chemical analyses of the natural bones were determined using by Electron Probe Micro-Analysis (EMPA). Structural, molecular and thermal characteristics were determined by X-ray Diffraction (XRD), Raman spectroscopy and Differential Thermal and Thermogravimetric analysis (DTA-TG). Cathodoluminescence (CL) spectra of natural bones and collagen showed similar intense broad bands at 440 and 490 nm related to luminescence of the tetrahedral anion ( PO 4 ) 3 - or structural defects. A weaker luminescence exhibited at 310 nm could be attributed to small amount of rare earth elements (REEs). Four luminescent bands at 378, 424, 468 and 576 nm were observed in the commercial hydroxyapatite (HAP). Both natural bones and collagen samples exhibited natural thermoluminescence (NTL) with well-defined glow curves whereas that the induced thermoluminescence (ITL) only appears in the samples of commercial hydroxyapatite and collagen. Additional explanations for the TL anomalous fading of apatite, as a crucial difficulty performing dosimetry and dating, are also considered.

Ni3–xCr2x/3(PO4)2 (x=0 and 0.02) microcrystalline powders were obtained as single phases via a modified sol–gel Pechini-type in situ polymerizable complex method. The samples were characterized using scanning electron microscopy, X-ray diffraction, cathodoluminescence (CL), and thermoluminescence (TL) techniques. We found that Cr3+ doping modified the average particle and distribution. The mean particle size was 0.441 μm for Ni3(PO4)2 and 0.267 μm for Ni2.98Cr0.013(PO4)2. The results also reveal that Cr3+ doping notably enhanced the CL and TL UV-blue emission.

The luminescence properties of gemstones (silicates, carbonates, phosphates, etc.), are of interest since could be potentially employed as personal dosimeters not only in case of radiation accident or radiological terrorism where conventional monitoring was not established, but also as a UV personal dosimeter. We, herein, report on preliminary results of the UV-induced 480 nm-thermoluminescence (TL) response of a well-characterised natural albite (NaAlSi3O8) from Minas Gerais (Brazil) that, due to its high transparency, is used as gemstone. Different annealing on several aliquots (from 480 to 960 °C) induces several changes in the sensitivity of the sample probably associated with (i) dehydration and dehydroxylation processes and (ii) changes in the lattice structure increasing the Al/Si disorder giving rise to ionic self-diffusion of alkali atoms, thermal stress into atomic positions and variation in the concentration of alkali ions in planar defects. The complex structure of albite has several planar defects (twinning and exsolution interphases which contain hydroxyl groups, water molecules, etc.) that can act as luminescence centres. When the thermal preannealed samples are exposed to 1 h at 254.7 nm under lab conditions one can appreciate changes in the TL behaviour that allows us to think in the albite as a potential UV dosimeter. ©2006 Elsevier Ltd. All rights reserved.

Olivine is an iron-magnesium solid solution silicate (Mg,Fe) 2 SiO 4 and it is probably one of the most abundant mineral phase in the Solar System, it is present in the primitive carbonaceous meteorites (i.e Allende), and in ordinary chondritic meteorite, comets or terrestrial planets. The olivine grains in those bodies have been exposed to different radiation sources like UV, electrons, cosmic radiation, etc. Here, we explore the effect of ionizing and non ionizing radiation on the luminescence emission of the two well-characterised olivine samples from Mexico and Spain by means of cathodoluminescence and thermoluminescence. The analyses by X-ray dispersive energies in the scanning electron microscopy show differences between the samples in the amount of iron and magnesium and also show traces of rare elements. Olivine exhibits spectral cathodoluminescence emissions of low intensity, explained for the quenching of the luminescence of the iron, and sharp signals assigned as impurities. Cathodoluminescence and thermoluminescence glow curves of the natural, and UV induced olivine samples were obtained. Our results show that thermal treatments at 1100 °C change the mineral molecular structure and the luminescence properties of this mineral phase. These results confirm an active participation of physical factors influencing the luminescent properties of olivine.

Castanar cave is a subterranean site with an outstanding natural environmental radioactivity. The maintaining of high radon activity of cave air and the detection of spatially anomalies of this gas in some cave emplacements, suggests that some natural geochemical processes are involved on the mobilization of radioactivity sources to cave environment, other than a simple exhalation of radon from the host-rock. The host rocks are interlaid dolostone–metapelite beds with radioactive nuclides of the three actinium, thorium and uranium decay series. In situ measurements on the spatial distribution of radioactivity, uranyl group’s luminescence and radon gas concentrations inside cave were main focus of this work to model lixiviation and deposition mechanisms of radioactive elements from the host rock to the karstic system. In addition, collected micro-samples were also analyzed by a multi-approach suite of analytical techniques: inductively coupled plasma mass spectrometry, environmental scanning electron microscopy with an attached X-ray energy dispersive system and spectral cathodoluminescence detector, thermoluminescence, Raman spectroscopy, X-ray diffraction, differential-thermal and thermogravimetry analysis, Alpha-spectrometry and Gamma-spectrometry techniques. The host metapelitic beds contain Zr(Hf)–Th(U)–Ti–P–REE phases such as zircon, xenotime-(Y), monazite-(Ce, La) and poly-metallic mineralization veins of hydrothermal origin. Carbonated host beds and speleothems show frequently chemical elements leaked from the upper host rock masses. The weathering leakage processes are favored by the existence of pyrite and limonite in the dolostone masses. The cave exhibits under UV lamps abundant hydrous silica–uranyl coatings covering carbonated speleothems with radionuclides of 238U natural decay series. The long-lived radio-nuclides of the radium radioactive decay chain are responsible of the continuous regeneration of radon gas inside cave. The experimental work was focused to identify origin and remobilization processes of radio-nuclides and their latte settlement into the cave environment associated to mineral phases of speleothems and cave deposits.

We herein report on the calculation of the activation energy (E a) from the thermoluminescence (TL) glow curves performed by the initial rise method that allows us to discriminate between irradiated and non-irradiated sesame seeds. E a values of natural TL (0.68 ± 0.03 eV) and gamma-induced TL (never lower than 0.82 ± 0.02 eV) appear as a complementary criterion to be used differentiating between irradiated and non-irradiated foodstuffs with the position and the intensity of the main peak of the TL emission. In addition, E a values taken from irradiated sesame samples at different doses (1, 5 and 10 kGy) and stored up to 15 months after being processed were compared to a ‘positive’ Spanish blend (i.e. at least one component was commercially irradiated).

We herein report on the cathodoluminescence (CL) and green-thermoluminescence (TL) emission ofCaSO 4 :Dy,P films deposited by the spray pyrolysis method at different temperatures. The samples havebeen previously structurally and chemically characterized by means of Raman spectroscopy and energydispersive spectroscopy (EDS). The CL spectra show (i) a broad emission band centered at 374 nm thatcorresponds to the intrinsic emission of (SO 4 ) 2 and (ii) emission bands centered on 486, 574, 668,758 nm assigned to the electronic transitions of the Dy 3þ ions. The TL glow curves of the films showedthree groups of components peaked at around of 98, 152 and 300 1C that exhibit a gradual andprogressively linear shifting of the T max as function of T stop . This TL behavior is related to a continuum inthe trap distribution associated with general or multi-order kinetics and involving continuousprocesses of trapping–detrapping. The activation energy in the range of 0.97–1.53 eV has beenestimated using the initial rise method.& 2012 Elsevier B.V. All rights reserved.

© 2015 Elsevier Ltd. The luminescence properties of natural white fluorite indicate that it could be employed as radiation dosimeter similarly to synthetic CaF2:Mn (TLD-400). The cathodoluminescence emission of the natural sample (two maxima) meanwhile TLD-400 (one peak) exhibits a different behaviour associated with the chemical composition. The mineral sample displays (i) a significant UV-blue emission associated with different structural defects (negligible in the synthetic sample) and (ii) a shift of the green emission to higher wavelengths respect to the TLD-400. The green induced TL emission also shows significant differences in intensity (higher in TLD-400) and sensitivity. Both samples display a complex induced green TL glow curve that could not be analysed assuming the model based on the discrete trap distribution. The Tm-Tstop method indicates the presence of close overlapping groups of components linked probably to a continuum in the trap distribution rather than a single trapping level.

Ce0.95Zr0.05O2 nanopowders have been prepared by a standard Pechini-type sol–gel process and by using polymethyl methacrylate (PMMA) colloidal crystals as template. The effects of these different synthesis routes, on the structure and microstructural features of the nanopowders, were evaluated by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area measurements. For both preparation routes, the XRD analysis has shown that a cubic fluorite structure is formed with a crystallite size of ∼45–50 nm. The SEM images indicate that the powder obtained by the sol–gel Pechini-type process, is constituted by aggregated nanoparticles with relatively uniform shape and size, whereas the powder synthesized as inverse opal exhibits the formation of macropores with a mean size of ∼130 nm. The specific surface areas of the powder samples obtained by the Pechini-type sol–gel and inverse opal methods are ∼56 m2 g−1 and ∼90 m2 g−1 respectively. Additionally, the thermoluminescence (TL) signal of the synthetized samples has been measured in order to examine its potential application in the field of dosimetry of ionizing radiations.

This paper reports on the Thermoluminescence (TL) and Cathodoluminescence (CL) emission of well-characterized hydrothermal milky quartz specimens from Hakkari in Turkey, labeled THQ, and Madrid in Spain, labeled SHQ, and metamorphic quartz from Madrid, in Spain, labeled SMQ. Both hydrothermal and metamorphic quartz samples display similar UV-IR CL spectra consisting of five groups of components centered at 330 nm and 380 nm linked to [AlO(4)]° centers, 420 nm due to intrinsic defects such as oxygen vacancies, lattice defects, and impurities which modify the crystal structure, 480 nm associated with [AlO(4)]° centers of substitutional Al(3+), and a red broad band related to the hydroxyl defects in the quartz lattice as precursors of non-bridging oxygen hole centers (NBOHC) and substitutional point defects. The Turkish quartz specimen exhibits higher CL intensity in the UV region (up to 330 nm) than the Spanish specimens probably linked to the presence of Ca (0.95% in THQ and less than 0.1% in SHQ and SMQ). At wavelengths greater than 330 nm, SMQ (formed at high pressure 6000 bars and temperatures over 500-600°C) shows higher intensity than the hydrothermal (growth at 2000 bars and temperatures 200-300°C) samples associated with the formation process. The natural blue TL glow curves of both THQ and SHQ display a weaker TL intensity than the SMQ, attributable to the Al (0.32%), Ti (0.14%), K (0.01%) and Zr (76 ppm) content. It is shown that mineralogical formation, crystallinity index and the content of the impurities seem to be the main parameters of influence in the shape intensity of the CL and TL glow curve emission.

The luminescence properties of synthetic alkali halides in general and different doped synthetic sodium chloride (NaCl) in particular have been widely studied. However, the spectral emission of natural NaCl has been scarcely reported. Accordingly, this work reports on the thermoluminescence (TL), infrared stimulated luminescence (IRSL) and radioluminescence (RL) response of the well-characterized natural NaCl (by means of X-ray fluorescence and differential thermal and thermogravimetric techniques) in the range of 200–800 nm. As observed in the 3D-TL plots, the main emission of the irradiated samples appears in the UV-blue region and can be deconvoluted into four groups of components (at 70, 180, 220 and 315 °C) assuming first order kinetics. The non-irradiated samples exhibited a negligible luminescence signal. The RL response reveals the appearance of five bands peaked at 290, 370, 430, 500 and 620 nm. The IRSL spectral emission shows a low intensity broad band with non-well defined peaks.

Micro-Raman and spatially resolved cathodoluminescence (CL) coupled to environmental electron microscope (ESEM) with energy dispersive spectrometry (EDS) are nondestructive techniques scarcely employed on renal calculi studies. This study used these techniques together with Electron Probe Micro-Analysis (EPMA), X-Ray diffraction (XRD), and Thermogravimetry (TG) to study a rare renal calculus with cystine and a common Ca-oxalate-apatite calculus in order to explore the applicability of these techniques. TG and XRD effectively determined the renal calculi, while ESEM and μ Raman provided useful information. The backscattering probe (BS) differentiates calculi with elements of dissimilar atomic masses such as P, S, and C. The authors inferred that the CL emission peaks at 325 (L-cystine-apatite) and 310 nm (Ca-oxalate) could be associated to oxygen hole center emission defects coupled with C—OH precursor bonds, while the CL spectral emission from the collagen proteins mask the hydroxyl-apatite spectra.

Most gemstones, being natural materials (silicates, carbonates, phosphates, etc.), exhibit luminescence emission. This property could be potentially employed for personal dosimetry in the case of radiation accident or radiological terrorism where conventional monitoring has not been established. We, herein, report on the thermoluminescence (TL), radioluminescence (RL) and infra-red stimulated luminescence (IRSL) response of a well-characterised natural amazonite (KAlSi3O8) that, due to its bright blue-green colour when polished, is used as a gemstone. The luminescence emission wavelengths, intensities and thermal kinetics of the amazonite luminescence curves reveal that the ultraviolet band measured on amazonite aliquots is similar to other common K-rich feldspars. On this basis, one can conclude (i) association between twinning and the UV-blue TL emission can be related to structural defects located in the twin-domain boundaries where ionic alkali-self-diffusion, irreversible water losses and irreversible dehydroxylation processes can be involved. (ii) Amazonite exhibits a complex structure with several planar defects (twinning and exsolution interphases which can hold hydroxyl groups, water molecules, etc.) and point defects (impurities, Na, Pb, Mn, etc.) that can act as luminescence centres, and in fact, green and red emissions are respectively associated with the presence of Mn and Fe impurities. Finally, (iv) the thermal stability tests performed on the TL emission of the amazonite confirm a continuum in the trap distribution, i.e. progressive changes in the glow curve shape, intensity and temperature position of the maximum peak.

The thermal stability of sodium oxalate (Na2C2O4) has been analyzed in the range of room temperature and 900 °C by different techniques. All of them, namely (i) environmental scanning electron microscopy (ESEM); (ii) differential-thermal analysis with simultaneous thermo-gravimetry (DTA–TG); (iii) temperature programmed decomposition mass spectrometry (TDP-MS); (iv) X-ray diffraction with heating stage (HS–XRD); (v) temperature programmed Raman spectroscopy (TP-Raman); and (vi) thermoluminescence (TL), provide information about the changes induced by thermal treatments. Thus, dehydration, decomposition, phase transition, decarbonylation, dissociation or lattice stress are some of the processes here described.

Twenty-five samples of saffron (11), pepper (9) and herbs, seasonings and spice blends (5) from Asia, South America, Africa and Europe have been analyzed by means of the EN 1788 protocol. The thermoluminescence (TL) emission of minerals isolated from the foodstuffs allows us to differentiate between irradiated (1) and non-irradiated (24) samples. According to the X-ray diffraction and environmental scanning microscope, the mineralogical composition adhered to the samples is mainly made up of different amounts of quartz, calcite, mica, gypsum, K and Na-rich feldspars, kaolinite, clinochlore and (only in mixtures) halite. All of them are sensitive to ionizing radiation, exhibit enough TL intensity, have high stability of the TL signal during the storage of the material, and are thermally and chemically stable. The EN 1788 European Standard arises as a reasonable protocol to discriminate among irradiated and non-irradiated food; nevertheless, it has some limitations that are discussed in the paper.

13 paginas, 6 figuras, et al, 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 microscopy and spectroscopy techniques. Teucrium gnaphalodes L’Her plants, growing in central Spain, develop galls induced by Copium insects. A survey of C. teucrii adult specimens resulted in surprising environmental scanning electron microscopy (ESEM) images, showing that their bright red eyes contain a calcium-phosphate mineralization. A complete survey of Copium eye specimens was performed by ESEM using energy-dispersive spectroscopy, backscattered electron detector and cathodoluminescence (CL) probes, field emission scanning electron microscopy, micro-Raman spectroscopy, and confocal laser scanning microscopy in order to learn ommatidia features, such as chemical composition, molecular structure, cell membrane, and internal ommatidium eye fluids and calcium-phosphate distribution deposits. The CL panchromatic images distinguish between the calcium-phosphate ommatidium and calcium-phosphate setae, which are more apatite rich. They show Raman bands attributable to bone tissue apatite biomaterials, such as bone, collagen, lipids, and blood, i.e., peptides, amide-S, amide-II, amide-III, and cytochrome P-450scc. The chemical composition of both galls and leaves of T. gnaphalodes was determined by gas chromatography – mass spectrometry (GC-MS) of their extracts. The spectrometric and microscopic images reveal that the calcium-phosphate mineralization is formed and constrained to Copium ommatidia, which are both matrix vesicles generating mixtures of apatite collagen and operational compound eyes of the insect., We are grateful to projects CGL2009-09247 and CGL2009-10111 of the Spanish PLAN NACIONAL DE I+D+i for financial support.

The blue thermoluminescence (TL) emission of different thermally annealed (i) β-eucryptite (LiAlSiO4), (ii) virgilite-petalite (LiAlSi5O12) and (iii) virgilite-petalite-bikitaite (LiAlSi10O22) mixed crystals have been studied. The observed changes in the TL glow curves could be linked to simultaneous processes taking place in the lithium aluminosilicate lattice structure (phase transitions, consecutive breaking linking of bonds, alkali self-diffusion, redox reactions, etc). The stability of the TL signal after four months of storage performed at RT under red light, shows big differences between annealed (12 hours at 1200ºC) and non-annealed samples. The fading process in non-annealed samples can be fitted to a first-order decay mathematical expression; however preheated samples could not be reasonably fitted due to the highly dispersion detected. The changes observed in the X-ray diffractograms are in the intensity of the peaks that denote modifications in the degree of crystallinity and, in addition, there are some differences in the appeareance of new peaks that could suppose new phases (e.g. β-spodumene).

The phase transition of metavariscite into berlinite has been studied by means of different techniques, namely electron probe micro analysis, environmental scanning electron microscopy, high-temperature X-ray diffraction, differential thermal analysis, thermogravimetry, thermoluminescence, and thermo Raman. The application of these techniques indicates that: (i) from room temperature to 150°C metavariscite (monoclinic dimorph AlPO4 ⋅ 2H2O) appears as the main phase, (ii) in the range of 100–300°C metavariscite starts to lose the water molecules giving rise to form α-berlinite (trigonal AlPO4) that is the stable phase up to ca 540°C, and (iii) from 550°C onwards the structure adopts the more stable configuration, tetragonal β-berlinite.

The thermal effect on the luminescence emission of a well-characterized natural kaolinite has been investigated by means of differential thermal analysis (DTA) and thermoluminescence (TL) to determine, respectively, the modifications of the material due to the thermal treatments up to 1000 °C and its potential use in the field of dating and retrospective dosimetry. The DTA detects water loss starting at 100–120 °C, a dehydroxylation process in the range of 400–500 °C and the transformation of kaolinite into metakaolinite at 570 °C. The dose dependence of the 400 nm TL intensity of kaolinite exhibits an excellent linearity in the range of 50 mGy to 8 Gy. In addition, the stability of the induced TL signal after six months of storage shows an initial rapid decay (ca. 60%) followed by a mild slope reaching the stability longer than six months. The tests of thermal stability at different temperatures allow us to speculate in a continuum of trap distribution with progressive changes in the glow curve shape, intensity and temperature position of the maximum peak. According to this thermal behavior, some physical parameters have been estimated using the initial rise method.

We, herein, study the thermoluminescence (TL) and cathodoluminescence (CL-SEM) emissions of a commercial turquoise to determine its possible use as an emergency dosimeter. CL spectrum of bulk sample displays an intense broad emission from ∼260 to ∼650 nm together with a weaker narrow band at ∼710 nm. Through EDS and EMPA chemical analyses, an important amount of rare earth elements (REE) such as Ce, La, Y, Nd, Dy, Yb, Er, Pr, Sm, Gd, Ho, Tb, and Tm have been identified associated with phosphate phases as well as in turquoise itself. Apatite [Ca 5 [OH(PO 4 ) 3 ]], monazite [(Ce,La,Nd,Th)PO 4 ], and xenotime [YPO 4 ] have been detected in the turquoise matrix, as well as very small amounts of quartz [SiO 2 ]. Turquoise has a high content in Zn 2+ substituting for Cu 2+ , together with small amounts of Cr 3+ substituting for Al 3+ . The well defined peak observed at ∼710 nm can be due to Cr 3+ activation centers in the turquoise lattice with the rest of the emissions associated with a REE activators and intrinsic defects. Regarding the blue TL, two emission bands (190° and 330 °C) appear in the natural aliquot whereas the irradiated sample displays no response at all. This glow emission could be due to the losses of structural water molecules in the turquoise lattice.

The thermoluminescence (TL) sensitivity to ionising (beta source) and non-ionising (UV) radiation on KCl:Eu 2+ single crystals has been investigated. The different shapes of the TL glow curves allow us to detect specific peaks (over 220–250 °C) due to UV exposure that exhibit a negligible contribution associated with ionising radiation. The UV-induced TL emission could be deconvoluted into five groups of components peaked at about 120, 150, 210, 250 and 330 °C assuming first order kinetic processes. Dose saturation and linearity region have been determined for a wavelength of 254.7 nm. The effect of several cycles of UV irradiation processes on the linearity of the high energy ultraviolet KCl:Eu 2+ dosimeter has been also studied to determine the potential reusability.

The KCl:Eu2+ system response to UV-C was investigated by analyzing the optically stimulated luminescence (OSL) and thermo-luminescence (TL) signal produced by ultraviolet light exposure at room temperature. It was found that after UV-C irradiation, OSL was produced on a wide band of visible wavelengths with decay time that varied by several orders of magnitude depending on the Eu2+ aggregation state. In spite of the low intensity of solar UV-C reaching the Earth's surface in Madrid (40o N, 700 m a.s.l.), it was possible to measure the UV-C radiation dose at 6:48 solar time by using the TL response of the KCl:Eu2+ system and differentiate it from the ambient beta radiation dose.

This paper reports on the dose response and fading effect of the blue thermoluminescence (TL) emission of lithium-rich aluminosilicates (virgilite–petalite mixture) synthesized by sol–gel method and characterised by means of X-ray diffraction. This material could be potentially valid for dose assessment since: (i) it is sensitive to ionising radiation, (ii) the dose dependence in the range of 0.5–5 Gy exhibits an acceptable linearity and (iii) the stability of the TL signal, after four months of storage, shows an initial rapid decay (ca. 55%) maintaining similar relative intensities from 40 to 50 days onwards. The structure of the TL emission has been analysed by means of a computerized glow curve fitting method based on general order kinetics. The calculation of the trapping parameters of each of the four glow peaks appearing at 80, 95, 110 and 125 °C (i.e. trap depth in eV, E ; frequency factor in s −1 , s , and the order of kinetics, b ) indicates that cannot be fitted to a typical first or second order kinetics; the estimated b values are between 1.1 and 1.8.

An historic Strontianite-type specimen from Strontian, Scotland, UK, was characterized to broaden our knowledge on luminescence properties of common carbonates. These fibrous aggregates are Strontianite (SrxCa1-xCO3) with circa 6% of CaO, interfacial water, hydrosilicate anions and substitutional divalent cations, e.g., Ca2+, Mn2+, Fe2+ in structural Sr2+ positions. The specimen was analyzed by X-ray Fluorescence Spectrometry (XRF), Environmental Scanning Electron Microscopy coupled with an Energy Dispersive X-ray Spectroscopy (ESEM-EDS) probe, Spatially-resolved Cathodoluminescence under the Scanning Electron Microscope (SEM-CL), Differential-Thermal Analyses (DTA), Thermogravimetry (TG), Thermoluminescence (TL), Radioluminescence (RL) and High Resolution Spectra Thermoluminescence (3DTL), to gain an overview of the spectral emissions, the defect linkages were modified by heating from room temperature (RT) up to 500 degrees C. Substitutional transition elements are probably responsible for the spectral emission bands from 500 nm to 800 nm and hydrous molecules from 300 nm to 400 nm. DTA-TG analyses performed on little chips, to preserve the fiber interfaces coherence. exhibit minor endothermic peaks attributed to outflow of water groups in fiber interfaces. Both, CL and RL curves show common spectral positions but UV-blue and red emission intensities are counterbalanced since electron irradiation reduces the UV-blue emissions while X-irradiation increases them. The TL curves show a top thermal limit at similar to 300 degrees C for the 300-400nm TL emissions which become irreversibly destroyed, whereas the longer wavelength region emits at higher temperature. The non-reversible changes observed in the 320 nm and 360 nm bands during the spectra 3DTL emission could be linked with non-bridging oxygen defects, protons and hydroxyl groups and the red emissions to the (4)G (T-4(1g))-S-6 Mn2+ ion transition. Following assignations and similar spectral CL patterns of Russian Strontianite samples, the emission-defect assignments: Dy3+ 480 nm: Tb3+ 540 nm; Dy3+ 580 nm and Sm3+ 640 nm cannot be disregarded. (C) 2009 Elsevier Ltd. All rights reserved.

The thermoluminescence (TL) response of silicon-rich daily-use materials, namely charoite (silicate gemstone), Spanish dental crown, phone chip and Spanish glass has been investigated. All the samples previously characterised by means of X-ray diffraction, electron microscopy associated with energy-dispersion and wavelength-dispersive spectrometry and X-ray fluorescence exhibit a reasonable sensitivity to ionising radiation. The preliminary results, based on their TL properties, allow us to speculate that these materials could be potentially of interest in situations where conventional dosimetric systems are not available. The dose dependence of the 400 nm TL emission of the studied samples displays a very good linearity in the range of 0.1–10 Gy. †Paper presented as a contribution to the 10th International Symposium on Solid State Dosimetry, Mexico City (24–28 September 2007).

The thermoluminescence (TL) properties of a well-characterised natural α-cristobalite from Lanzarote (Canary Islands, Spain) have been studied. The natural blue emission (at 400 nm) of this silica polymorph of quartz reveals the appearance of three groups of components peaked at 150, 230–240 and 370 °C, which could be associated, respectively, with (i) structural defects (similar to quartz), (ii) the reversible phase transition from α-cristobalite to β-cristobalite and (iii) electron recombination with unstable holes trapped at oxygen vacancies next to Al ions linked to the formation of β-cristobalite. Similar to quartz, the induced TL (ITL) glow curves display four maxima, peaked at 90, 110, 180 and 220 °C, which could be respectively associated with (i) oxygen vacancies, (ii) recombination of electrons with (H3O4)° centres that can act as hole traps, (iii) [GeO4]− centres that are stabilised with monovalent cations (H+, Li+ or Na+) and (iv) [AlO4]° hole-like centres that are created when alkali ions are...

This work is focused on the study of the thermally stimulated blue emission of aluminium oxide (Al2O3) that has been removed from twenty different high alumina-rich refractory bricks. The glow curve sensitivity of several alumina grains are defined by (i) a maximum centred at about 165°C that can be deconvoluted into two first order kinetic peaks at 157 and 177°C and (ii) a broad structure over 200–220°C that suggests a continuous trap distribution system. The isolated grains, analysed by means of X-ray diffraction, are composed of 43% of alumina (Al2O3), 22% of mullite [72% of Al2O3 and 28% of SiO2], 12% of leucite (KAlSi2O6) and 23% of sillimanite [Al2O3·SiO2]. The sample characterization has been performed using X-ray fluorescence and scanning electron microscopy.