Surface and Bulk Crystallization Kinetics of Er3+ Doped Mixed Alkali Phosphate Glasses

2010 ◽  
Vol 146-147 ◽  
pp. 1142-1146
Author(s):  
Yong Zheng Fang ◽  
Jia Yue Xu ◽  
Zhang Yong Wang ◽  
Hui Chun Qian
Keyword(s):  
Thermal Stability ◽  
Particle Size ◽  
Phosphate Glasses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bulk Crystallization ◽  
Dsc Measurements ◽  
Mixed Alkali ◽  
Kinetics Of ◽  
Dsc Curves

DSC measurements have been carried out for the as-quenched xNa2O- (15-x)Li2O-4B2O3-11Al2O3-5BaO-65P2O5 (x=0,3.75,7.5,11.25 and 15 mol%) glasses with different particle size. Two crystallization peaks appear on the DSC curves for sample sized 90-110μm. The presence of two crystallization peaks is due to different crystallization mechanisms, surface and bulk (internal) crystallization. The X-ray diffraction measurements are also employed to investigate the crystallization of glasses. The results show that bulk crystallization is difficult to occur in the studied phosphate glasses. The effect of mixed alkali on glass thermal stability is also studied in this paper. The surface and bulk crystallization active energies are calculated according to Kissinger equation.

scholarly journals Thermal Stability and Kinetics of Formation of Magnesium Oxychloride Phase 3Mg(OH)2∙MgCl2∙8H2O

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 767 ◽  
Author(s):  
Michal Lojka ◽  
Ondřej Jankovský ◽  
Adéla Jiříčková ◽  
Anna-Marie Lauermannová ◽  
Filip Antončík ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Construction Materials ◽  
Simultaneous Thermal Analysis ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Sustainable Building ◽  
X Ray ◽  
Kinetics Of Formation ◽  
Magnesium Oxychloride ◽  
Kinetics Of

In this paper, magnesium oxychloride cement with stoichiometry 3Mg(OH)2∙MgCl2∙8H2O (MOC 3-1-8) was prepared and characterized. The phase composition and kinetics of formation were studied by X-ray diffraction (XRD) and Rietveld analysis of obtained diffractograms. The chemical composition was analyzed using X-ray fluorescence (XRF) and energy dispersive spectroscopy (EDS). Furthermore, scanning electron microscopy (SEM) was used to study morphology, and Fourier Transform Infrared (FT-IR) spectroscopy was also used for the analysis of the prepared sample. In addition, thermal stability was tested using simultaneous thermal analysis (STA) combined with mass spectroscopy (MS). The obtained data gave evidence of the fast formation of MOC 3-1-8, which started to precipitate rapidly. As the length of the time of ripening increased, the amount of MgO decreased, while the amount of MOC 3-1-8 increased. The fast formation of the MOC 3-1-8 phase at an ambient temperature is important for its application in the production of low-energy construction materials, which corresponds with the challenges of a sustainable building industry.

Thermal stability of nanocrystalline WC–Co powder synthesized by using mechanical milling at low temperature

2001 ◽  
Vol 16 (2) ◽  
pp. 478-488 ◽  
Author(s):  
Jianhong He ◽  
Leoanardo Ajdelsztajn ◽  
Enrique J. Lavernia
Keyword(s):  
Thermal Stability ◽  
Particle Size ◽  
Mechanical Milling ◽  
Gradual Increase ◽  
Thermal Exposure ◽  
X Ray Diffraction ◽  
Cryomilled Powder ◽  
X Ray ◽  
Increasing Temperature ◽  
Thermal Stability Of

Nanostructured WC–18% Co powder was synthesized by using cryogenic mechanical milling, and the thermal stability of the nanostructured powder was investigated in detail. The results indicated that the as-synthesized WC–18% Co powder had an average WC particle size of 25 nm. Growth of WC particles occurred above 873 K; however, the average WC particle size remained smaller than 100 nm in the powder isothermally heated for 4 h at 1273 K. Thermal exposure in air at T < 623 K did not result in significant oxidation of the cryomilled powder. The thermal exposure did promote the formation of WO2 and WO3 oxides. The Co6W6C phase was detected by x-ray diffraction in the powder heated in nitrogen at 1273 K, and the phases associated with decarburization of WC, such as W2C, W3C phases, were not observed. With increasing temperature, the dissolution of W and C elements in the Co matrix led to a gradual increase in {111} crystallographic plane spacing, eventually leading to the formation of an amorphous phase.

scholarly journals SINTESIS DAN KARAKTERISASI FAUJASIT DARI ABU LAYANG : Kajian Pengaruh Waktu Sintesis Terhadap Stabilitas Termal Struktur Faujasit (Kinetics of Faujasite Formation from Fly Ash)

2019 ◽  
Vol 2 (2) ◽  
pp. 10
Author(s):  
Sutarno Sutarno ◽  
Arief Budyantoro
Keyword(s):  
Thermal Stability ◽  
Fly Ash ◽  
Amorphous Phase ◽  
Zeolite Y ◽  
Weight Ratio ◽  
Hydrothermal Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Kinetics Of ◽  
Thermal Stability Of

Faujasite was hydrothermally synthesized from fly ash at 100oC in alkaline solution by reflux with 5M HCl and fusion with NaOH (weight ratio of NaOH/fly ash = 1.2) pretreatments. Kinetics of faujasite formation was performed by variation of hydrothermal time (0-120 hours). Thermal stability of faujasite from fly ash was tested at 400-900oC and was compared with commercial zeolite Y. The solid products were characterized by X-ray diffraction method. Results showed that faujasite was formed through dissolution of fly ash components such as quartz, mullite and amorphous aluminosilicates (0-3 hours) followed by crystallization to form faujasite (6-48 hours). In longer hydrothermal time (48-72 hours), faujasite transformed into zeolite P and completely formed hydroxysodalite after 120 hours. X-ray diffraction pattern showed that thermal stability of faujasite from fly ash was relatively lower than that of commercial zeolite Y. Faujasite from fly ash transformed into amorphous phase at 800oC whereas commercial zeolite Y transformed into amorphous phase at 900oC.

scholarly journals THERMAL BEHAVIOR OF PARACETAMOL AND TABLETS OF REFERENCE, GENÉRIC AND SIMILAR

2012 ◽  
Vol 09 (17) ◽  
pp. 28-37
Author(s):  
Francisca Edivânia MORAIS ◽  
Sheila Pricila Marques CABRAL ◽  
Eliane Gonçalves ARAUJO ◽  
Carlos Alberto MARTINEZ-HUITLE ◽  
Nedja Suely FERNANDES
Keyword(s):  
Particle Size ◽  
Thermal Behavior ◽  
Pharmaceutical Formulations ◽  
Endothermic Peak ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermoanalytical Techniques ◽  
Diffraction Patterns ◽  
Dsc Curves

The present study utilized the thermoanalytical techniques (TG, DTG, DTA and DSC) to evaluate the thermal behavior of tablets containing paracetamol and marketed as reference, generic and similar. The samples were also characterized by IR, X-ray diffraction and SEM. The TG/DTG curves presented similar behaviour indicanting a low influence of the excipients present in pharmaceutical formulations. The DTA and DSC curves showed an endothermic peak between about 165.0 and 195.0 oC characteristic of melting of paracetamol in all samples. The X-ray diffraction patterns showed similarities and characterized the compounds as crystallines. The micrographs indicated heterogeneity in particle size.

scholarly journals Crystallization kinetics of K2O·TiO2·3GeO2 glass studied by DTA

2008 ◽  
Vol 40 (3) ◽  
pp. 333-338 ◽  
Author(s):  
S. Grujic ◽  
N. Blagojevic ◽  
M. Tosic ◽  
V. Zivanovic ◽  
J. Nikolic
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Particle Size ◽  
Differential Thermal Analysis ◽  
Crystallization Kinetics ◽  
Crystallization Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Powder Samples ◽  
Kinetics Of

Crystallization kinetics of K2O?TiO2?3GeO2 glass was investigated by differential thermal analysis (DTA). Experiments were performed on powder samples with a particle size < 0.037 mm. The glass samples were heated at different rates in the temperature range 20-750?C. The kinetic parameters, activation energy for the crystallization process, Ec and Avrami exponent, n were calculated. Powder X-ray diffraction analysis (XRD) of crystallized glass reveals the presence of crystalline K2O?TiO2?3GeO2 indicating polymorphic crystallization with interface controlled crystal growth.

scholarly journals Fabrication of Nanoparticle-Stacked 1,1-Diamino-2,2-Dinitroethylene (FOX-7) Microspheres with Increased Thermal Stability

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Yuanping Zhang ◽  
Conghua Hou ◽  
Xinlei Jia ◽  
Jinyu Wang ◽  
Yingxin Tan
Keyword(s):  
Thermal Stability ◽  
Particle Size ◽  
Performance Test ◽  
Crystal Form ◽  
Sem Analysis ◽  
Test Results ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Scanning Electron

Nanoparticle-stacked 1,1-diamino-2,2-dinitroethylene (FOX-7) microspheres were successfully prepared by spray-drying, and rod-shaped FOX-7 was obtained by the solvent/nonsolvent method for comparison. The microstructure features of samples were characterized using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD), and the thermal properties were also investigated by differential scanning calorimetry (DSC). From the SEM analysis, the particle size of the rod-shaped FOX-7 is about 10 μm, whereas FOX-7 microspheres having a particle size ranging from 1 to 5 μm are formed by stacking nanoparticles with size of 100-250 nm. The crystal form of the samples prepared by the two methods did not change. The thermal performance test results showed that the rd-shaped FOX-7 had no significant change compared with the raw FOX-7, while the nanoparticle-stacked FOX-7 microspheres had higher thermal stability.

Study on Crystallization Kinetics of Li2O-Al2O3-TiO2-P2O5 Glass by Non-Isothermal Technique

2012 ◽  
Vol 535-537 ◽  
pp. 1629-1633 ◽  
Author(s):  
Yan Hang Wang ◽  
Kun He ◽  
Cheng Kui Zu ◽  
Jiang Chen
Keyword(s):  
Crystallization Kinetics ◽  
Annealing Temperature ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Crystallization Peak ◽  
X Ray ◽  
Xrd Techniques ◽  
Kinetics Of ◽  
Dsc Curves ◽  
Crystalline Growth

The crystallization kinetics of Li2O-Al2O3-TiO2-P2O5 (LATP) glass was studied by differential scanning calorimeter (DSC) and X-ray diffraction (XRD) techniques. The results showed that DSC curves of LATP glass have a single glass transition temperature followed by one crystallization peak for β = 5 K/min and two crystallization temperatures Tp1 and Tp2 for β ≥ 10 K/min. The activation energies of crystallization obtained from Kissinger model of the first exothermal peak and the second exothermal peak of LATP glass are 251 kJ/mol and 310 kJ/mol, respectively. The Avrami exponents of the both crystallization peaks are approximately 3, indicating that the three-dimensional crystalline growth during its amorphous to crystalline transformation. LiTi2(PO4)3 and unknown crystalline phases firstly form when the mother glass was annealed at 973 K. With increasing of annealing temperature, AlPO4 phase appears.

scholarly journals Stable and Metastable Phase Equilibria Involving the Cu6Sn5 Intermetallic

2021 ◽  
Author(s):  
A. Leineweber ◽  
M. Löffler ◽  
S. Martin
Keyword(s):  
Phase Equilibria ◽  
Electron Backscatter Diffraction ◽  
Metastable Phase ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Ordered Phases ◽  
Backscatter Diffraction ◽  
Kinetics Of

Abstract Cu6Sn5 intermetallic occurs in the form of differently ordered phases η, η′ and η′′. In solder joints, this intermetallic can undergo changes in composition and the state of order without or while interacting with excess Cu and excess Sn in the system, potentially giving rise to detrimental changes in the mechanical properties of the solder. In order to study such processes in fundamental detail and to get more detailed information about the metastable and stable phase equilibria, model alloys consisting of Cu3Sn + Cu6Sn5 as well as Cu6Sn5 + Sn-rich melt were heat treated. Powder x-ray diffraction and scanning electron microscopy supplemented by electron backscatter diffraction were used to investigate the structural and microstructural changes. It was shown that Sn-poor η can increase its Sn content by Cu3Sn precipitation at grain boundaries or by uptake of Sn from the Sn-rich melt. From the kinetics of the former process at 513 K and the grain size of the η phase, we obtained an interdiffusion coefficient in η of (3 ± 1) × 10−16 m2 s−1. Comparison of this value with literature data implies that this value reflects pure volume (inter)diffusion, while Cu6Sn5 growth at low temperature is typically strongly influenced by grain-boundary diffusion. These investigations also confirm that η′′ forming below a composition-dependent transus temperature gradually enriches in Sn content, confirming that Sn-poor η′′ is metastable against decomposition into Cu3Sn and more Sn-rich η or (at lower temperatures) η′. Graphic Abstract

scholarly journals Mining Wastes of an Albite Deposit as Raw Materials for Vitrified Mullite Ceramics

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 232
Author(s):  
Pedro J. Sánchez-Soto ◽  
Eduardo Garzón ◽  
Luis Pérez-Villarejo ◽  
George N. Angelopoulos ◽  
Dolores Eliche-Quesada
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Phase Evolution ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Mining Wastes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Value

In this work, an examination of mining wastes of an albite deposit in south Spain was carried out using X-ray Fluorescence (XRF), X-ray diffraction (XRD), particle size analysis, thermo-dilatometry and Differential Thermal Analysis (DTA) and Thermogravimetric (TG) analysis, followed by the determination of the main ceramic properties. The albite content in two selected samples was high (65–40 wt. %), accompanied by quartz (25–40 wt. %) and other minor minerals identified by XRD, mainly kaolinite, in agreement with the high content of silica and alumina determined by XRF. The content of Na2O was in the range 5.44–3.09 wt. %, being associated with albite. The iron content was very low (<0.75 wt. %). The kaolinite content in the waste was estimated from ~8 to 32 wt. %. The particle size analysis indicated values of 11–31 wt. % of particles <63 µm. The ceramic properties of fired samples (1000–1350 °C) showed progressive shrinkage by the thermal effect, with water absorption and open porosity almost at zero at 1200–1250 °C. At 1200 °C, the bulk density reached a maximum value of 2.38 g/cm3. An abrupt change in the phase evolution by XRD was found from 1150 to 1200 °C, with the disappearance of albite by melting in accordance with the predictions of the phase diagram SiO2-Al2O3-Na2O and the system albite-quartz. These fired materials contained as main crystalline phases quartz and mullite. Quartz was present in the raw samples and mullite was formed by decomposition of kaolinite. The observation of mullite forming needle-shape crystals was revealed by Scanning Electron Microscopy (SEM). The formation of fully densified and vitrified mullite materials by firing treatments was demonstrated.

Study on Adsorption of Crosslinked Starch Microspheres towards Heavy Metal Ions

2013 ◽  
Vol 834-836 ◽  
pp. 531-535
Author(s):  
Li Yan Yang ◽  
Yi Hui Guo ◽  
Li Li Yu ◽  
Jing You
Keyword(s):  
Metal Ions ◽  
Reversed Phase ◽  
Adsorption Rate ◽  
X Ray Diffraction ◽  
Adsorption Selectivity ◽  
X Ray ◽  
Starch Microsphere ◽  
Other Substances ◽  
Effects Of Media ◽  
Kinetics Of

A type of cross-linking starch microsphere (CSMs) has been synthesized via reversed phase suspension method. Crosslinked starch microsphere has good adsorption performance to metal ions in water. The adsorption kinetics of Co (II) on the CSMs, selectivity of adsorption CSMs towards Co (II),Cu (II),Pb (II),Cd (II) and adsorption effects of media towards Co (II) were investigated. The CSMs and its adsorption product were comparatively characterized by X-ray diffraction (XRD). The results showed that The adsorption rate is mainly controlled by liquid film diffusion, and the constant of adsorption rate is 0.0686min-1 at 308K. The crystal structure of the CSMs decreased greatly after the incorporation of Co (II). Co (II) has better adsorption selectivity on CSMs. Ions coexist and other substances in the solution have certain impact on adsorption. Those data are helpful for treatment of the wastewater containing heavy ions.

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