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.

Effects of Phosphorus and Fluorine on the Crystallization and Structure of CaO-A12O3-SiO2 System Glass-Ceramic

2008 ◽  
Vol 368-372 ◽  
pp. 1412-1414 ◽  
Author(s):  
Jin Shu Cheng ◽  
Hui Guang Qiu ◽  
Hong Li ◽  
Jun Xie
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Scanning Electron Microscopy ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Yellow Phosphorus ◽  
Crystallization Of Glass ◽  
Scanning Electron

CaO-A12O3-SiO2 (CAS) system glass-ceramics were prepared by sintering with certain amount of yellow phosphorus slag. The effects of phosphorus and fluorine on the nucleation, crystallization and structure of CAS system glass-ceramics were investigated by differential thermal analysis, X-ray diffraction, scanning electron microscopy and other measuring methods. Glass-ceramics of CAS system with 42.32wt% yellow phosphorus slag were obtained by nucleating at 615°C for 1 hour and crystallizing at 926°C for 2 hours. The results showed that the introduction of phosphorus and fluorine promoted the nucleation and crystallization of glass-ceramics, lowering the crystallizing temperature. The main crystal phase of glass-ceramics was β-wollastonite. The density of the glass-ceramic was 2.695g/cm3.

The Effect of MgO Dopant on the Dielectric Properties of CaCu3Ti4O12 Ceramics

2012 ◽  
Vol 620 ◽  
pp. 219-223 ◽  
Author(s):  
Mohd Fariz Ab Rahman ◽  
Julie Juliewatty Mohamed ◽  
Mohd Fadzil Ain ◽  
Sabar Derita Hutagalung
Keyword(s):  
Single Phase ◽  
Lattice Expansion ◽  
Secondary Phases ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Scanning Electron ◽  
Mg Doped

The properties of undoped and Mg-doped CaCu3Ti4O12 (CCTO) ceramics have been studied. The samples were calcined at 900°C for 12 hours, and sintered at 1030°C for 10 hours. X-ray diffraction analysis on calcined samples shown the formation of CCTO phase with trace of secondary phases meanwhile completed formation of CCTO single phase obtained for sintered pellets. The peak positions of Mg-doped CCTO were slightly left-shifted from the undoped CCTO, attributed to the lattice expansion. Scanning electron microscopy analysis showed that the grains size becomes larger with the increment of dopant amount. Enhanced dielectric constant was observed in the Ca1-xMgxCu3Ti4O12 ceramics with x = 0.05 for the frequency range from 1 MHz to 1 GHz. The dielectric loss seem to be at lowest value when Ca1-xMgxCu3Ti4O12 ceramics with x = 0.10 at the same frequency range. The results indicate that Mg ions have effectively changed the properties of CCTO.

Production of 3Y-PSZ Powders by Co-Precipitation and Milling

2008 ◽  
Vol 54 ◽  
pp. 50-55
Author(s):  
Erika Furlani ◽  
Eleonora Aneggi ◽  
Stefano Maschio
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Amorphous Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Attrition Milling ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Co Precipitation ◽  
Scanning Electron

The present research compares properties and behaviour of co-precipitated 3Y-PSZ powders submitted, after co-precipitation, to different milling treatments. The characteristics of the different products were evaluated by measurement of particle size distribution, thermogravimetric analysis, X-ray diffraction, specific surface area and scanning electron microscopy analysis. It has been demonstrated that 1h of attrition milling enables the production of powders with micrometric particles: the dispersing liquid used on milling has little influence. Crystallization of the amorphous powder is achieved after 1h of high energetic milling, without any thermal treatment.

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 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.

scholarly journals Solvothermally derived Me2(H2O)4(5SSA)3·DMF and Me2(H2O)4(4NSA)2·DMF: Application as Biginelli reaction catalysts

Chemija ◽  
2019 ◽  
Vol 30 (2) ◽  
Author(s):  
Andrius Laurikėnas ◽  
Fatma Yalçin ◽  
Robertas Žilinskas ◽  
Ayse Uztetik Morkan ◽  
Albinas Žilinskas ◽  
...  
Keyword(s):  
Solvothermal Synthesis ◽  
Catalytic Properties ◽  
Inorganic Compounds ◽  
Biginelli Reaction ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hybrid Compounds ◽  
Phase And Chemical Composition ◽  
Scanning Electron

The solvothermal synthesis between Me(NO3)x ∙ yH2O (Mex+ = Fe3+, Ni2+, Mn2+, Co2+, Cu2+) and respectively 4-nitrosalycilic (4NSA) and 5-sulfosalicylic (5SSA) acids produced hybrid organic-inorganic compounds composed of Mex+ ions and organic fragments which include three different functional groups, carboxylic, hydroxyl and sulfonic, each coordinated to the Mex+ ions. The phase and chemical composition, microstructure and properties of Me2(H2O)4(5SSA)3·DMF and Me2(H2O)4(4NSA)2·DMF (DMF – dimethylformamide) hybrid compounds were evaluated and discussed. The synthesised materials were characterised by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) spectroscopy. The catalytic properties of the obtained compounds were also investigated.

scholarly journals Photocatalytic Degradation of Nitro and Chlorophenols Using Doped and Undoped Titanium Dioxide Nanoparticles

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Hassan Ilyas ◽  
Ishtiaq A. Qazi ◽  
Wasim Asgar ◽  
M. Ali Awan ◽  
Zahir-ud-din Khan
Keyword(s):  
Photocatalytic Degradation ◽  
Crystallite Size ◽  
Model Compound ◽  
Titanium Dioxide Nanoparticles ◽  
Xrd Analysis ◽  
Scanning Electron Micrographs ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Impregnation ◽  
Scanning Electron

Pure and Ag-TiO2nanoparticles were synthesized, with the metallic doping being done using the Liquid Impregnation (LI) method. The resulting nanoparticles were characterized by analytical methods such as scanning electron micrographs (SEMs), Energy Dispersive Spectroscopy (EDS), and X-ray diffraction (XRD). XRD analysis indicated that the crystallite size ofTiO2was 27 nm to 42 nm while the crystallite size of Ag-TiO2was 11.27 nm to 42.52 nm. The photocatalytic activity of pureTiO2and silver dopedTiO2was tested by photocatalytic degradation ofp-nitrophenol as a model compound. Ag-TiO2nanoparticles exhibited better results (98% degradation) as compared to pureTiO2nanoparticles (83% degradation) in 1 hour for the degradation ofp-nitrophenol. Ag-TiO2was further used for the photocatalytic degradation of 2,4-dichlorphenol (99% degradation), 2,5-dichlorophenol (98% degradation), and 2,4,6-trichlorophenol (96% degradation) in 1 hour. The degree of mineralization was tested by TOC experiment indicating that 2,4-DCP was completely mineralized, while 2,5-DCP was mineralized upto 95 percent and 2,4,6-TCP upto 86 percent within a period of 2 hours.

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 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.

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