scholarly journals Effect of Different Concentrations of Titanium Oxide (TiO2) Addition on the Crystallization Behaviour and Some Properties of Alkaline Earth Aluminosilicate Glass-Ceramics

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Z.S. Aliyu
Keyword(s):  
Glass Ceramic ◽  
Minimum Weight ◽  
Glass Ceramics ◽  
Aluminosilicate Glass ◽  
Base Glass ◽  
Ceramic Samples ◽  
Melting Technique ◽  
The Matrix ◽  
Quaternary Base ◽  
Tio2 Addition

Glass-ceramics in the CaO-MgO-Al2O3-SiO2 quaternary base glass system was produced via melting technique using feldspar, limestone and magnesite as sources of starting materials. Glass-ceramics production involves making a base glass, annealing and cooling to room temperature and then reheating the base glass to nucleation and crystal growth temperatures. Characterization of the produced glass-ceramics was carried out using a scanning electron microscope (SEM). The effects of the crystallization process on some properties such as hardness, chemical durability in acid and alkali media of samples were determined. The results portrayed that glass-ceramic samples to which various amounts of TiO2 (2,4,6,8 and 10 wt.%) were incorporated showed the formation of crystalline phases dispersed in the matrix of their respective residual glassy phases. Significant improvement in hardness, as well as minimum weight loss, were recorded for all the glass-ceramic samples. On the contrary, the glass samples did not crystallize despite subjecting them to heat treatment, their hardness values were low and they were not resistant to acid (1M HCl) and alkali (1M NaOH) attacks. The inability of TiO2 addition to fully transform them into glass-ceramics remains a shortcoming. However, the glass-ceramic samples obtained from this study can be used for tiling works.

Deformation and fracture of mica-containing glass-ceramics in Hertzian contacts

1994 ◽  
Vol 9 (3) ◽  
pp. 762-770 ◽  
Author(s):  
Hongda Cai ◽  
Stevens Marion A. Kalceff ◽  
Brian R. Lawn
Keyword(s):  
Glass Ceramic ◽  
Material Removal ◽  
Glass Ceramics ◽  
Fatigue Properties ◽  
Base Glass ◽  
Compressive Stresses ◽  
Contact Loads ◽  
Deformation And Fracture ◽  
The Matrix ◽  
Microstructural Design

The Hertzian indentation response of a machinable mica-containing glass-ceramic is studied. Relative to the highly brittle base glass from which it is formed, the glass-ceramic shows evidence of considerable “ductility” in its indentation stress-strain response. Section views through the indentation sites reveal a transition from classical cone fracture outside the contact area in the base glass to accumulated subsurface deformation-microfracture in the glass-ceramic. The deformation is attributed to shear-driven sliding at the weak interfaces between the mica flakes and glass matrix. Extensile microcracks initiate at the shear-fault interfaces and propagate into the matrix, ultimately coalescing with neighbors at adjacent mica flakes to effect easy material removal. The faults are subject to strong compressive stresses in the Hertzian field, suggesting that frictional tractions are an important element in the micromechanics. Bend-test measurements on indented specimens show that the glass-ceramic, although weaker than its base glass counterpart, has superior resistance to strength degradation at high contact loads. Implications of the results in relation to microstructural design of glass-ceramics for optimal toughness, strength, and wear and fatigue properties are discussed.

HIPed Tailored Pyrochlore-Rich Glass-Ceramic Waste Forms for the Immobilization of Nuclear Waste

2008 ◽  
Vol 1124 ◽  
Author(s):  
Melody Lyn Carter ◽  
Hui Li ◽  
Yingjie Zhang ◽  
Andrew L Gillen ◽  
Eric R Vance
Keyword(s):  
Nuclear Waste ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Spectroscopic Characterization ◽  
Chemical Durability ◽  
Intermediate Level ◽  
Crystalline Phases ◽  
Waste Forms ◽  
Ceramic Samples

AbstractHot isostatically pressed (HIPed) glass-ceramics for the immobilization of uranium-rich intermediate-level wastes and Hanford K-basin sludges were designed. These were based on pyrochlore-structured Ca(1-x)U(1+y)Ti2O7 in glass, together with minor crystalline phases. Detailed microstructural, diffraction and spectroscopic characterization of selected glass-ceramic samples has been performed, and chemical durability is adequate, as measured by both MCC-1 and PCT-B leach tests.

scholarly journals Photoluminescence of Eu and Ce Activated Oxyfluoride Glass And Glass Ceramics/ Eu Un Ce Jonu Luminiscence Oksifluorīdu Stiklos Un Stikla Keramikā

2012 ◽  
Vol 49 (6-I) ◽  
pp. 44-48
Author(s):  
I. Brice ◽  
U. Rogulis ◽  
E. Elsts ◽  
J. Grūbe
Keyword(s):  
Glass Ceramic ◽  
Glass Ceramics ◽  
Oxyfluoride Glass ◽  
Ceramic Samples ◽  
Activator Ions

Abstract The photoluminescence of SiO2-Al2O3-LiO2-LaF3 oxyfluoride glass and glass ceramic samples doped with Ce3+, Eu2+ and Ce3+/Eu2+ is investigated, and the spectra and fluorescence intensities are compared. The luminescence of samples activated by Eu ions is found to be more intensive than of the samples doped with Ce or Ce/Eu. The luminescence of glass ceramics is higher than that of the corresponding glass, which indicates that a proportion of the activator ions are embedded in the fluoride crystallites.

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.

Study of Glass-Ceramic Waste Forms

1997 ◽  
Vol 506 ◽  
Author(s):  
S.V. Stefanovsky ◽  
S.V. Ioudintsev ◽  
B.S. Nikonov ◽  
B.I. Omelianenko ◽  
T.N. Lashtchenova
Keyword(s):  
Glass Ceramic ◽  
Glass Composition ◽  
Glass Ceramics ◽  
High Level Waste ◽  
Matrix Glass ◽  
Crystalline Phases ◽  
Cell Parameters ◽  
The Matrix ◽  
High Level ◽  
Similar Unit

ABSTRACTSince the early of the 1990s the method of inductive melting in a cold crucible (IMCC) has been applied at SIA “Radon” for production of various wasteforms, including glasses and Synroc-type ceramics. Sphene-based glass-ceramics composed of glass and crystalline phases were considered as appropriate wasteform for High Level Waste immobilisation. Investigation of two glass-ceramic specimens prepared with the IMCC has been performed using optical microscopy, XRD, SEM/EDS, and TEM methods. The samples produced consist of vitreous and crystalline phases. The vitreous phase consists of two varieties of glass formed by the immiscibility of the initial melt onto two separate liquids. One of the glasses is observed as spherical microinclusions in the matrix glass. The glass of the microspheres are differed from the matrix glass composition by higher contents of Ca, Ti, Ce, Sr, Zr (or Cr), while the matrix glass contains higher amounts of Si, Al, and alkalies. The crystalline phases with sphene- and perrierite-like structures have been also occurred. Their total quantity reaches up to 50 vol.%. The synthetic perrierite has similar unit-cell parameters with its natural mineral analogs with the only exception in two-fold value of c dimension. Zr, Ce, and Sr are incorporated into synthetic sphene and perrierite, while Cs is hosted by the glass phases.

scholarly journals Impact of Morphology and Microstructure on the Mechanical Properties of Ge-As-Pb-Se Glass Ceramics

2020 ◽  
Vol 10 (8) ◽  
pp. 2836 ◽  
Author(s):  
Rashi Sharma ◽  
Rebecca Welch ◽  
Myungkoo Kang ◽  
Claudia Goncalves ◽  
Cesar Blanco ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Vickers Hardness ◽  
Glass Ceramic ◽  
Volume Fraction ◽  
Glass Ceramics ◽  
Post Heat Treatment ◽  
Base Glass ◽  
Parent Glass ◽  
Crystal Phases

The impact of base glass morphology and post heat-treatment protocol on the mechanical properties (Vickers hardness and Young’s modulus) of a multi-component glass-ceramic was examined. Two parent chalcogenide glasses with identical composition but varying morphology (homogeneous and phase separated) were evaluated for their mechanical properties following identical thermal processing to induce crystallization. The nucleation and growth rates of the starting materials were compared for the two glasses, and the resulting crystal phases and phase fractions formed through heat treatment were quantified and related to measured mechanical properties of the glass ceramics. The presence of a Pb-rich amorphous phase with a higher crystal formation tendency in the phase-separated parent glass significantly impacted the volume fraction of the crystal phases formed after heat-treatment. Pb-rich cubic crystal phases were found to be dominant in the resulting glass ceramic, yielding a minor enhancement of the material’s mechanical properties. This was found to be less than a more moderate enhancement of mechanical properties due to the formation of the dominant needle-like As2Se3 crystallites resulting from heat treatment of the homogeneous, commercially melted parent glass. The greater enhancement of both Vickers hardness and modulus in this glass ceramic attributable to the high-volume fraction of anisotropic As2Se3 crystallites in the post heat-treated commercial melt highlights the important role base glass morphology can play on post heat-treatment microstructure.

scholarly journals Surface Plasmon Resonance Enhanced Spontaneous Upconversion and Stimulated Emissions in Glass Ceramics Containing Ba2LaF7 Nanocrystals

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Sai Li ◽  
Wei Lu ◽  
Qihua Yang ◽  
Dacheng Zhou ◽  
Jianbei Qiu ◽  
...  
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Glass Ceramic ◽  
Visible Region ◽  
Glass Ceramics ◽  
Random Lasing ◽  
Ag Nps ◽  
The Matrix ◽  
Quenching Method

Glass ceramics containing Yb3+, Er3+ codoped Ba2LaF7 nanocrystals were fabricated via melt quenching method and the subsequent heating treatment. The formation of Ba2LaF7 nanocrystals in the glass ceramics was confirmed by X-ray diffraction (XRD) and transmission electron microscope (TEM). The spontaneous upconversion (UC) emission and the stimulated counterpart as a random lasing action of Er3+, which were related to the characteristic transitions of Er3+ ions, were achieved in the Yb3+, Er3+-doped Ba2LaF7 nanocrystals embedded glass ceramic hybrid. Furthermore, the absorption spectra verified the surface plasmon resonance (SPR) band of Ag, which precipitated from the matrix glasses as Ag nanoparticles (NPs). By incorporating Ag NPs in the glass ceramic hybrid, spontaneous UC emission intensity of Er3+ in visible region was significantly enhanced, while the threshold of the random lasing was decreased from 480 to 350 nJ/cm2.

Zn2+- Controlled Crystallization and Microstructure in K-Li-Mg-B-Si-Al-F Glass

MRS Advances ◽  
2018 ◽  
Vol 3 (60) ◽  
pp. 3525-3533 ◽  
Author(s):  
Mrinmoy Garai ◽  
Anoop K. Maurya ◽  
Shibayan Roy
Keyword(s):  
Heat Treatment ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Ceramic ◽  
Vickers Microhardness ◽  
Glass Ceramics ◽  
Network Modifier ◽  
Base Glass ◽  
Controlled Crystallization

Abstract Text:The crystallization of (9-X) K2O-1Li2O-12MgO-10B2O3-40SiO2-16Al2O3-12MgF2-X PbO/BaO/ZnO (X =0/5) composition (wt.%) were studied by means of dilatometry, DSC, XRD, SEM and microhardness analysis. Density of base K-Li-Mg-B-Si-Al-F glass (2.59 g.cm–3) is found to be increased on addition of the network modifier oxides PbO, BaO and ZnO content. Addition of Pb2+, Ba2+ and Zn2+ furthermore increased the glass transition temperature (Tg.). A characteristic exothermic hump is found to be appeared in DSC thermograph at the temperature range 800-950°C; and that is ascribed to the formation of crystalline phase fluorophlogopite mica, KMg3(AlSi3O10)F2. Opaque glass-ceramics were prepared from K-Li-Mg-B-Si-Al-F glasses (with and without containing PbO, BaO and ZnO content) by controlled heat-treatment at 1000°C. Interlocked type microstructure combined of flake like fluorophlogopite mica crystals is obtained in ZnO-containing K-Li-Mg-B-Si-Al-F glass-ceramic; and such microstructural pattern is ascribed to cause large thermal-expansion (>11.5×10-6/K, 50-800°C).Vickers Microhardness of base glass-ceramic (5.12 GPa) is increased when contains ZnO (5.26 GPa). ZnO-containing boroaluminosilicate glass-ceramic is, hence, considered with potential interest as they can exhibit the microcrack resistivity in high temperature recycling operation (like SOFC).

scholarly journals Investigation on Structural and Optical Properties of Willemite Doped Mn2+Based Glass-Ceramics Prepared by Conventional Solid-State Method

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Nur Farhana Samsudin ◽  
Khamirul Amin Matori ◽  
Josephine Ying Chi Liew ◽  
Yap Wing Fen ◽  
Mohd Hafiz Mohd Zaid ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Glass Ceramics ◽  
Structural Evolution ◽  
Emission Spectra ◽  
Soda Lime ◽  
X Ray Diffraction ◽  
Glass Waste ◽  
Solid State Method ◽  
Ceramic Samples ◽  
Zno Crystal

Mn-doped willemite (Zn2SiO4:Mn2+) glass-ceramics derived from ZnO-SLS glass system were prepared by a conventional melt-quenching technique followed by a controlled crystallization step employing the heat treatment process. Soda lime silica (SLS) glass waste, ZnO, and MnO were used as sources of silicon, zinc, and manganese, respectively. The obtained glass-ceramic samples were characterized using the X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared (FTIR), UV-Visible (UV-Vis), and photoluminescence (PL) spectroscopy. The results of XRD revealed that ZnO crystal and willemite (β-Zn2SiO4) were presented as major embedded crystalline phases. This observation was consistent with the result of FESEM which showed the presence of irregularity in shape and size of willemite crystallites. FTIR spectroscopy exhibits the structural evolution of willemite based glass-ceramics. The optical band gap shows a decreasing trend as the Mn-doping content increased. Photoluminescent technique was applied to characterize the role of Mn2+ions when entering the willemite glass-ceramic structure. By measuring the excitation and emission spectra, the main emission peak of the glass-ceramic samples located at a wavelength of 585 nm after subjecting to 260 nm excitations. The following results indicate that the obtained glass-ceramics can be applied as phosphor materials.

Study on the Preparation and Properties of Piezoelectric Glass-Ceramic Sr0.5Ba0.5Nb2O6

2013 ◽  
Vol 669 ◽  
pp. 204-207
Author(s):  
Shan Jiang ◽  
Jing Wen Lv ◽  
Tao Zheng
Keyword(s):  
Particle Size ◽  
Glass Ceramic ◽  
Crystalline Phase ◽  
Room Temperature ◽  
Glass Ceramics ◽  
Molar Ratio ◽  
Spectral Transmittance ◽  
Melting Method ◽  
Ceramic Samples ◽  
Analytical Reagents

Series of ferroelectric glass-ceramic samples of Sr0.5Ba0.5Nb2O6 were synthesized by melting method. Firstly, analytical reagents were melted for 30 minutes at 1440°C after being grinded evenly according to a certain molar ratio, then annealed for 10 hours from 550°C to room temperature, finally it was sustained for 4 hours at constant temperature about 700°C. The hardness and transmittance parameters of SBN glass-ceramic were tested. Results indicated the sample had the best property when the amount of Nb2O5 was 10mol%, whose hardness reached 506 kg/mm2, and spectral transmittance was higher than 35% . XRD spectra of this sample indicated this SBN glass-ceramics contained a large number of Sr0.5Ba0.5Nb2O6 crystalline phase and a small amount of Sr0.3Ba0.7Nb2O6 phase. The particle size was about 50 nm.

Sign in / Sign up

Export Citation Format

Share Document