scholarly journals Formation of nanostructures in Eu3+ doped glass–ceramics: an XAS study

2014 ◽  
Vol 70 (a1) ◽  
pp. C959-C959
Author(s):  
Julio Pellicer-Porres ◽  
Alfredo Segura ◽  
Gema Martínez-Criado ◽  
Ulises Rodríguez-Mendoza ◽  
Víctor Lavín
Keyword(s):  
Amorphous Phase ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Aluminosilicate Glass ◽  
Chemical Information ◽  
Nanocrystalline Phase ◽  
X Ray Diffraction ◽  
Oxyfluoride Glass ◽  
X Ray ◽  
X Ray Absorption

Lead-aluminosilicate oxyfluoride transparent glass–ceramics doped with RE3+ ions have been revealed to be unique in the field of optical material engineering. This kind of material consists of a beta_x000C_-PbF2 fluoride nanocrystalline phase in an aluminosilicate glassy amorphous phase. In this way, the macroscopic properties of this material are characteristic of aluminosilicate glass, whereas the spectroscopic properties of the RE3+ ions remain those of low-phonon-energy fluoride crystals. The optical properties of the RE3+ ions, and therefore their interest for photonic applications, depend on the final environment of these ions in a host matrix. Exploration of the local structure of the Eu3+ ions as well as characterization of the amorphous matrix demands structural techniques that do not rely on long range order. Given the complexity of the system under study, chemical selectivity is also required. In this work [1], we describe the results of x-ray absorption experiments carried out to deduce structural and chemical information in Eu3+ doped, transparent, oxyfluoride glass and nanostructured glass–ceramic samples. The spectra were measured at the Pb and Eu–LIII edges. The Eu environment in the glass samples is observed to be similar to that of EuF3. Complementary x-ray diffraction experiments show that thermal annealing creates _x000C_beta-PbF2 type nanocrystals. X-ray absorption indicates that Eu ions act as seeds in the nanocrystal formation. There is evidence of interstitial fluorine atoms around Eu ions as well as Eu dimers. X-ray absorption at the Pb–LIII edge shows that after the thermal treatment most lead atoms form a PbO amorphous phase and that only 10% of the lead atoms remain available to form _x000C_beta-PbF2 type nanocrystals. Both x-ray diffraction and absorption point to a high Eu content in the nanocrystals. Our study suggests new approaches to the oxyfluoride glass–ceramic synthesis in order to further improve their properties.

scholarly journals Preliminary investigation of chlorine speciation in zirconolite glass-ceramics for plutonium residues by analysis of Cl K-edge XANES

MRS Advances ◽  
2019 ◽  
Vol 5 (1-2) ◽  
pp. 37-43
Author(s):  
Amber R. Mason ◽  
Stephanie M. Thornber ◽  
Martin C. Stennett ◽  
Laura J. Gardner ◽  
Dirk Lützenkirchen-Hecht ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Absorption Edge ◽  
Glass Ceramic ◽  
Glass Phase ◽  
Preliminary Investigation ◽  
Glass Ceramics ◽  
Local Environment ◽  
Aluminosilicate Glass ◽  
X Ray ◽  
X Ray Absorption

ABSTRACTA zirconolite glass-ceramic material is a candidate wasteform for immobilisation of chlorine contaminated plutonium residues, in which plutonium and chlorine are partitioned to the zirconolite and aluminosilicate glass phase, respectively. A preliminary investigation of chlorine speciation was undertaken by analysis of Cl K-edge X-ray Absorption Near Edge Spectroscopy (XANES), to understand the incorporation mechanism. Cl was found to be speciated as the Cl- anion within the glass phase, according to the characteristic chemical shift of the X-ray absorption edge. By comparison with Cl K-edge XANES data acquired from reference compounds, the local environment of the Cl- anion is most closely approximated by the mineral marialite, in which Cl is co-ordinate to 4 x Na and/or Ca atoms.

scholarly journals Study of the effect of Ca/Mg alkali-oxides ratio on the structure of a glass-ceramic based on an aluminosilicated glass containing 2wt.% of zirconolite crystalline phase

2014 ◽  
Vol 46 (3) ◽  
pp. 377-383
Author(s):  
R. Souag ◽  
N. Kamel ◽  
Y. Mouheb ◽  
M. Hammadi ◽  
Z. Kamel ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Glass Ceramics ◽  
Xrd Analysis ◽  
Aluminosilicate Glass ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Alkali Oxides ◽  
Scanning Electron

New nuclear glass-ceramics are extensively studied for the radioactive waste confinement, due to the double confinement conferred by the glass-ceramics. In this study, a glass-ceramic constituted by an aluminosilicate glass in the system: SiO2-Al2O3-CaO-MgOZrO2-TiO2, containing 2wt.% of Ca0.83Ce0.17ZrTi1.66Al0.34O7 zirconolite, has been synthesized by the discontinuous method. Cerium, an actinide surrogate is introduced both in the glass and ceramic phases. The synthesis is performed by a double melting at 1350?C, followed by a nucleation at 564?C, during 2 h, and a crystal growth at 1010?C during 3 h. Then effect of Ca/Mg ratio on the distribution of the crystalline network in the material was studied for Ca / Mg ratios ranging from 0.4 to 5.5. For the whole of the materials, Archimedes density is about 2.80 g/cm3. X-ray diffraction (XRD) analysis shows that the increase of Ca/Mg ratio leads to the increase of aluminosilicated crystalline phases with high Ca contents; the materials molar volumes remaining constant. The zirconolite phase is not affected by these additive aluminosilicated phases. The scanning electron microscopy analysis (SEM) coupled with energy dispersive X-ray (EDX) analysis confirmed these results; and shows the uniformity of distribution of the ceramics in the bulk of the materials.

Differential anomalous wide-angle X-ray scattering and X-ray absorption experiments to investigate the formation of glass ceramics in the CaO–SiO2–ZrO2system

1999 ◽  
Vol 32 (6) ◽  
pp. 1090-1099 ◽  
Author(s):  
Carlo Meneghini ◽  
Alessandro F. Gualtieri ◽  
Cristina Siligardi
Keyword(s):  
Glass Ceramic ◽  
Room Temperature ◽  
Glass Ceramics ◽  
Anomalous Scattering ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Two Samples ◽  
Devitrification Process ◽  
X Ray Absorption

The structure of a CaO–SiO2–ZrO2-based glass ceramic has been investigated by X-ray diffraction, X-ray absorption spectroscopy and differential anomalous scattering techniques as a function of the thermal treatment of the sample. The microstructure of the glass has been investigated at room temperature, before the recrystallization of the glass ceramic, and on two samples annealed at 1073 and 1273 K for 1 h to follow the early stages of nucleation of the quartz and wollastonite crystalline phases. Indications on the roles of Ca, Si and Zr during the devitrification process are given.

scholarly journals Bone bonding ability of some borate bio-glasses and their corresponding glass-ceramic derivatives

2012 ◽  
Vol 6 (4) ◽  
pp. 183-192 ◽  
Author(s):  
Fatma Margha ◽  
Amr Abdelghany
Keyword(s):  
Heat Treatment ◽  
Fourier Transform ◽  
Glass Ceramic ◽  
Glass Composition ◽  
Glass Ceramics ◽  
Soda Lime ◽  
Phosphate Solution ◽  
Borate Glasses ◽  
X Ray Diffraction ◽  
X Ray

Ternary borate glasses from the system Na2O?CaO?B2O3 together with soda-lime-borate samples containing 5 wt.% of MgO, Al2O3, SiO2 or P2O5 were prepared. The obtained glasses were converted to their glass-ceramic derivatives by controlled heat treatment. X-ray diffraction was employed to investigate the separated crys?talline phases in glass-ceramics after heat treatment of the glassy samples. The glasses and corresponding glass-ceramics after immersion in water or diluted phosphate solution for extended times were characterized by the grain method (adopted by several authors and recommended by ASTM) and Fourier-transform infrared spectra to justify the formation of hydroxyapatite as an indication of the bone bonding ability. The influence of glass composition on bioactivity potential was discussed too.

Structure Characterization of Sintered CaO-Al2O3-SiO2 Glass-Ceramic Reinforced with Spodumene

2013 ◽  
Vol 834-836 ◽  
pp. 309-314
Author(s):  
Zi Fan Xiao ◽  
Jin Shu Cheng ◽  
Jun Xie
Keyword(s):  
Glass Ceramic ◽  
Energy Dispersive Spectrometry ◽  
Crystal Size ◽  
Bending Strength ◽  
Glass Ceramics ◽  
Structure Characterization ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
X Ray

A glass-ceramic belonging to the CaO-Al2O3-SiO2(CAS) system with different composition of spodumene and doping the Li2O with amount between 0~2.5 % (mass fraction) were prepared by onestage heat treatment, under sintering and crystallization temperature at 1120 °C for two hours. In this paper, differential thermal analysis, X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and bending strength test were employed to investigate the microstructure and properties of all samples. β-wollastonite crystals were identified as the major crystalline phases, and increasing Li2O was found to be benefit for the crystallization and tiny crystalline phases remelting, resulting in the content of major crystalline phases increased first and then decreased with increasing the expense of spodumene. Meanwhile, the crystal size can be positively related with the content of Li2O. The preferable admixed dosage of spodumene can be obtained, besides the strength of glass-ceramics can be more than 90 MPa.

scholarly journals Five-fold twinned β-PbF2 nanocrystals in oxyfluoride glass ceramics

RSC Advances ◽  
2018 ◽  
Vol 8 (71) ◽  
pp. 40787-40793 ◽  
Author(s):  
Yuao Guo ◽  
Lijuan Zhao ◽  
Yuting Fu ◽  
Pan Dong ◽  
Liying Guo ◽  
...  
Keyword(s):  
Glass Ceramics ◽  
Lanthanide Ions ◽  
X Ray Diffraction ◽  
Oxyfluoride Glass ◽  
X Ray ◽  
Trivalent Lanthanide ◽  
Quenching Method

Oxyfluoride glass ceramics (GCs) doped with trivalent lanthanide ions (Ln3+) have been prepared using a conventional melting–quenching method and studied by X-ray diffraction (XRD).

Upconversion Luminescence Properties of NaYF4 Nanocrystals Precipitated Nd3+/Yb3+/Ho3+ Tri-Doped Oxyfluoride Glass Ceramics

2016 ◽  
Vol 16 (4) ◽  
pp. 3744-3748 ◽  
Author(s):  
Yuan Gao ◽  
Yuebo Hu ◽  
Dacheng Zhou ◽  
Jianbei Qiu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Transfer Process ◽  
Upconversion Luminescence ◽  
Glass Ceramics ◽  
X Ray Diffraction ◽  
Oxyfluoride Glass ◽  
X Ray ◽  
Transmission Electron ◽  
The Matrix

Transparent oxyflouride glass ceramics composed of SiO2–Al2O3–Na2O–NaF–YF3 tri-coped with Nd3+/Yb3+/Ho3+ were prepared by thermal treatment. Segregation of NaYF4 nanocrystals in the matrix was confirmed from structural analysis by means of X-ray diffraction and transmission electron microscopy. Compared with glass samples, very strong green upconversion (UC) luminescence due to the Ho3+:(4F5, 5S2)→5I8 transition was observed in the glass ceramics under 808 nm excitation. It was found that upconversion intensity of Ho3+ strongly depends on the Nd3+ concentration, and the energy transfer process from Nd3+ to Ho3+ via Yb3+ was proposed.

MgO-Al2O3-SiO2 Glass-Ceramic Prepared by Sol-Gel Method

2010 ◽  
Vol 92 ◽  
pp. 131-137 ◽  
Author(s):  
Qiu Hua Yuan ◽  
Pei Xin Zhang ◽  
Li Gao ◽  
Hai Lin Peng ◽  
Xiang Zhong Ren ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Crystallization Behavior ◽  
Glass Powder ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Green Body ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Sio2 Glass ◽  
X Ray

The crystallization behavior of MgO-Al2O3-SiO2 glass-ceramics by sol-gel technology was investigated by using x-ray diffraction (XRD), differential thermal analysis (DTA), Scanning electron microscopy (SEM). The results showed that: (1)α-cordierite phase was precipitated when the green body was calcined at 1050°C, and α-cordierite of high purity and stability could be formed at 1100°C; (2) Adding an appropriate amount of low melting point glass powder into the green body may provide liquid-phase environment during the sintering process, which will help enhance the tightness density of glass-ceramic, and thus improve its flexural strength.

Crystallization and Mechanical Properties of Glass-Ceramic from Silicon Slag

2014 ◽  
Vol 953-954 ◽  
pp. 1643-1648
Author(s):  
Hang Li ◽  
Li Qiang Liu ◽  
Min Jing ◽  
Zhi Gang Wang ◽  
Zheng Wang ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Mechanical Performance ◽  
Glass Ceramics ◽  
Ceramic Materials ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Talcum Powder ◽  
X Ray ◽  
Glass Ceramic Materials ◽  
Spherical Grains

The glass-ceramic materials were produced from silicon slag with the addition of talcum powder and TiO2 by melting them in an electrically heated furnace and subsequent heat treatment at various temperatures and time. The microstructure and crystallization behaviors of glass–ceramics have been investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). With the increase of silicon slag content, the sequent precipitate phase is: krinovite Na (Mg1.9Fe0.1)Cr (SiO)3O, pseudobrookite Fe2TiO5 and anorthite Ca (Al2Si2O8), enstatite ferroan MgFeSi2O6, and albite Na (AlSi3O8). The shape of crystals was spherical grains. The glass–ceramic sample obtained from 70% silicon slag had the excellent mechanical performance including flexural strength of 200.45 MPa and Vickers micro hardness of 909.72 MPa.

Formation of Eu-Doped CaF2 Naonocrystals in Glass-Ceramics by Infrared Laser Irradiation

2015 ◽  
Vol 749 ◽  
pp. 211-214
Author(s):  
Dong Seon Kim ◽  
Jin Ho Lee ◽  
Ki Soo Lim
Keyword(s):  
Glass Ceramics ◽  
Dopant Distribution ◽  
X Ray Diffraction ◽  
Oxyfluoride Glass ◽  
Strong Emission ◽  
X Ray ◽  
Exposed Region ◽  
Crystalline Environment ◽  
Confocal Fluorescence ◽  
Infrared Laser Irradiation

Glass-ceramic was precipitated on the oxyfluoride glass surface by thermal annealing with a CO2 laser and a heat gun. Micro x-ray diffraction showed the formation of CaF2 ain the exposed region to the laser. Dopant distribution in glass ceramics was probed by confocal fluorescence microscope by observing much strong emission from Eu ions than the glassy area under 405 nm excitation. Much enhanced visible emissions under 365 nm excitation also showed well incorporation of Eu3+ ions into a crystalline environment.

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