scholarly journals Investigation DSC and XRD on the Crystallization Kinetics in the Phosphate Li2O−Li2WO4−TiO2−P2O5 Glassy Ionic System

2021 ◽  
Author(s):  
Hicham ES-SOUFI ◽  
L. Bih ◽  
Alan R. F. Lima ◽  
A. El Bouari ◽  
B. Manoun ◽  
...  
Keyword(s):  
Crystallization Process ◽  
Glass Ceramics ◽  
Chemical Durability ◽  
Surface Crystallization ◽  
Vibrational Modes ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
X Ray ◽  
Activation Energy Of Crystallization ◽  
Avrami Parameter

Abstract This work aims to investigate the prepared glasses within the 20Li2O−(50−x)Li2WO4−xTiO2−30P2O5 system, with 0≤x≤15 mol%. The bonds constituting the framework of these glasses were studied by Raman spectroscopy. The data analysis of the chemical durability showed that the dissolution rates depend on the composition of each glass. Thermal analysis by DSC technique was used to determine the activation energy of crystallization, it found in the glass of composition (x= 5) that Ec= 184.482 kJ/mol. The determinate Avrami parameter is around 1.7 which allows suggesting the mechanism is surface crystallization. The crystallization process of the prepared glasses is carried out by heating samples at 550°c for 4 hours and 12 hours. The crystallized phases are identified by XRD. The results of X−ray diffraction analysis confirm that TiO2 acts mainly as network forming units. The crystalline phases Li2WO4 (JCPDS# 01−072−0086) and (JCPDS# 01−087−0409) are formed during the crystallization process. The formation of these crystalline phases into the glasses depends on the time of heating at fixed crystallization temperature. FTIR spectra of the glass–ceramics show nearly the same IR vibrational modes as their parent glasses.

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.

Effects of Glass Elements on the Structural Evolution ofin situGrown Ferroelectric Perovskite Crystals in Sol-gel Derived Glass-ceramics

1997 ◽  
Vol 12 (4) ◽  
pp. 1131-1140 ◽  
Author(s):  
Kui Yao ◽  
Weiguang Zhu ◽  
Liangying Zhang ◽  
Xi Yao
Keyword(s):  
Crystallization Process ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Structural Evolution ◽  
Dielectric Measurements ◽  
X Ray Diffraction ◽  
Process Change ◽  
X Ray ◽  
Ferroelectric Perovskite

Several ABO3perovskite ferroelectric crystals, PbTiO3, Pb(Zr, Ti)O3, and BaTiO3have beenin situgrown from amorphous gels with glass elements, and the structural evolution has been systematically investigated using x-ray diffraction (XRD), infrared spectra (IR), differential thermal analysis (DTA), thermogravimetric analysis (TGA), and dielectric measurements. It is found that in the Si-contained glass-ceramic systems, Si and B glass elements are incorporated into the crystalline structures, resulting in the variation of the crystallization process, change of lattice constant, and dielectric properties. Some metastable phases expressed by a general formula AxByGzOw(A = Pb and Ba; B = Zr and Ti; G for glass elements, especially for Si) have been observed and discussed.

Surface Crystallization of ZnO-Al2O3-SiO2 Glass

2007 ◽  
Vol 280-283 ◽  
pp. 1655-1658
Author(s):  
Xiao Dong Li ◽  
Jie Mo Tian ◽  
Chen Wang ◽  
Li Min Dong
Keyword(s):  
Heat Treatment ◽  
Treatment Time ◽  
Glass Ceramics ◽  
Surface Crystallization ◽  
X Ray Diffraction ◽  
Crystalline Layer ◽  
Surface Conditions ◽  
X Ray ◽  
Treatment Processes ◽  
Electronic Microscope

ZnO-Al2O3-SiO2 glasses with different surface conditions were surface crystallized by different heat treatment process. Differential thermal analysis (DTA), X-ray diffraction analysis (XRD) and scanning electronic microscope (SEM) were used to investigate the crystallization behavior of glasses, the crystalline components and microstructure of the as-got glass-ceramics. According to the DTA results, different heat treatment processes of surface crystallization on the glass were adopted. The SEM results show that surface conditions of glasses are important for the surface crystallization, and the thickness of surface crystalline layer increases with heat treatment time.

Study of the Evolution of Phase Calcium Aluminate through the Method for Polymeric Precursors C12A7

2015 ◽  
Vol 820 ◽  
pp. 137-142
Author(s):  
Faili Cintia Tomsen Veiga ◽  
Flávio José Tomsen Veiga ◽  
Mário Lúcio Moreira ◽  
José Jurado ◽  
Vânia Caldas Sousa ◽  
...  
Keyword(s):  
Calcium Aluminate ◽  
Ceramic Materials ◽  
Vibrational Modes ◽  
X Ray Diffraction ◽  
Precursor Method ◽  
Crystalline Phases ◽  
Polymeric Precursors ◽  
X Ray ◽  
Pure Phase ◽  
The Subject

The synthesis of ceramic materials from polymeric precursors has been the subject of numerous studies due to lower energy cost compared to conventional processing. The study aims to research and develop synthesis of calcium aluminate powders via the polymeric precursor method, in order to obtain the pure phase of hepta-aluminate dodecálcio (C12A7) with mayenita mineral name, since it has applications like: special cements and components for high temperature fuel cells. A study of the evolution of crystalline phases by X-ray diffraction was performed, the vibrational modes of atomic location in crystalline phases were studied by micro-Raman spectroscopy was also performed and images from scanning electron microscopy. From the characterizations carried out on the material can be seen that the sintering temperature of 1200°C was obtained pure phase, so the choice of synthesis shown to be effective due to the complexity of obtaining this phase pure.

Investigation of Nucleation and Crystallization Behavior of Li2O-MgO-Al2O3-SiO2-MgF2 Glass-Ceramics System

2014 ◽  
Vol 1044-1045 ◽  
pp. 63-66 ◽  
Author(s):  
Zheng Cao ◽  
Xiu Quan Zhao ◽  
Hong Jiang ◽  
Chang Jiu Li ◽  
Yang Shen ◽  
...  
Keyword(s):  
Glass Ceramics ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Base Glass ◽  
X Ray ◽  
Appropriate Treatment ◽  
Activation Energy Of Crystallization ◽  
Main Crystalline Phase ◽  
Alumino Silicate ◽  
Sem Morphology

The glass-ceramics were produced via heat treatment from bulk base glass at the appropriate treatment temperatures provided by the differential thermal analysis (DTA) measurement. The effect of nucleation on crystallization kinetics has been explored. It is found that nucleation indeed decreased the activation energy of crystallization. X-ray diffraction (XRD) analysis demonstrated that the main crystalline phase was magnesium alumino-silicate (MgAl2Si3O10), Scanning electron microscopy (SEM) morphology showed that the crystals were needle-like in all the samples.

The Study of Crystallization Dynamics of Amorphous Precursor Fe70Mo5Cr4Nb6B15 Alloy

2018 ◽  
Vol 69 (2) ◽  
pp. 318-320
Author(s):  
Konrad Gruszka ◽  
Jakub Rzacki ◽  
Marcin Nabialek
Keyword(s):  
Heat Treatment ◽  
Crystallization Process ◽  
Amorphous Structure ◽  
X Ray Diffraction ◽  
Isothermal Heating ◽  
Amorphous Precursor ◽  
Crystalline Phases ◽  
X Ray ◽  
Crystallization Dynamics

The paper presents the results of studying the dynamics of the crystallization process for the samples subjected to three separate processes of isothermal heating with three different energy in the process. For this purpose, a series of samples prepared in the form of a ribbon of an amorphous structure, as confirmed from X-ray diffraction were then subjected to a controlled annealing. The research of samples after heat treatment revealed the presence of different crystalline phases that are characterized by different nucleation energies.

Effects of B2O3 Contents on Crystallization Behaviors and Dielectric Properties of CaO-B2O3-SiO2 Glass Ceramics

2016 ◽  
Vol 680 ◽  
pp. 301-305 ◽  
Author(s):  
Ai Qing Jia ◽  
Wei Jun Zhang ◽  
Xing Yu Cheng ◽  
Zhuo Feng Liu
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Dielectric Properties ◽  
Boron Content ◽  
Glass Ceramics ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
X Ray ◽  
Scanning Electron

The CaO-B2O3-SiO2 glass ceramics system with four different boron contents (14 wt. %, 16.4 wt. %, 18.6 wt. %, 21 wt. %) were prepared under 900oC. The properties and microstructures are characterized by Differential Scanning Calorimeter (DSC), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The effects of boron contents on the composition of crystalline phases and the properties of CaO-B2O3-SiO2 glass ceramics system were studied. The results show that when the molar ratio of CaO/SiO2 is 1.06, as the content of B2O3 increases, the major crystalline phases experiences the transformation from CaSiO3 to CaB2O4 and the content of α-SiO2 crystalline phase decreases, and the dielectric constant increases firstly but it decreases after the content of B2O3 reaches to 18.6 wt. %, while the dielectric loss tgδ of decreases gradually with the addition of boron content. When the content of B2O3 is 16.4 wt. %, the CaO-B2O3-SiO2 glass ceramics with a bulk density of 2.47 g/cm3 exhibits good dielectric properties (1 MHz): εr=6.03, tgδ=3.49×10-3.

Influence of Nucleating Additions on the Crystallization in the CaO-MgO-Al2O3-SiO2 Glass-Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 1408-1411 ◽  
Author(s):  
Qing Bo Tian ◽  
Yue Wang ◽  
Li Ming Feng ◽  
Xiu Hui Wang ◽  
Hong Gao
Keyword(s):  
Glass Ceramics ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Crystalline Phases ◽  
Layer Compound ◽  
X Ray ◽  
Fibrous Morphology ◽  
Inner Region ◽  
Compound Surface ◽  
Fine Dendrite

The crystallization behaviors and microstructural developments in the CaO-MgO- Al2O3-SiO2 glass with Fe2O3, ZrO2 and F as additives were investigated by using scanning electron microscopy, X-ray diffraction and differential scanning calorimetry techniques. In the glass sample with 1.0wt% Fe2O3, only surface crystallization were observed, in which a three-layer compound surface containing the fine dendrite, finer fibrous morphology and particle-shaped crystals was formed respectively from the near free surface to the inner region. The crystalline phases precipitated were anorthite and wollastonite at 1000°C, and diopside at 1040°C. The addition of ZrO2 suppressed the nucleation and growth of the crystalline phases. The addition of another 4.0wt% fluorine into the glass with a pair of 1.0wt% Fe2O3 and 2.0wt% ZrO2 induced the bulk crystallization, the surface and bulk crystallizations were both observed at 1040°C. At the surface, a three-layer morphology, which had similar morphology to the glass with 1.0wt% Fe2O3 was formed. In the bulk region, the block-shaped crystalline phases were precipitated homogeneously in the residual glass.

The Effect of Waste Loading on the Characteristics of Borosilicate SRS SB4 Waste Glasses

2009 ◽  
Author(s):  
Sergey Stefanovsky ◽  
Alexander Kobelev ◽  
Vladimir Lebedev ◽  
Michael Polkanov ◽  
Dmitriy Suntsov ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Spinel Structure ◽  
Glass Ceramics ◽  
Chemical Durability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Infra Red ◽  
Inner Diameter ◽  
Waste Loading ◽  
High Concentrations

The glasses containing surrogate of Sludge Batch 4 (SB4) waste with high concentrations of aluminum and ferrous oxides within the waste loading (WL) range of ∼50 to 70 wt.% produced in alumina crucibles in a resistive furnace and in a 236 mm inner diameter cold crucible were examined by X-ray diffraction, electron microscopy and infra-red spectroscopy. At relatively low WLs (50 to 60 w.%) the products remain predominantly vitreous with minor crystalline spinel structure phase corresponding in chemical composition to trevorite-magnetite solid solution. At higher WLs (>60 wt.%) amount of crystalline phases increased significantly and a nepheline phase was observed. The products with WL of 65 to 70 wt.% were spinel/nepheline glass-ceramics. The glass with 60 wt.% WL slowly cooled in accordance with the canister centerline cooling (CCC) conditions contained minor nepheline. Occurrence of nepheline reduces the chemical durability of nuclear waste glasses.

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