The effect of CaO/SiO2 and B2O3 on the sintering contraction behaviors of CaO-B2O3-SiO2 glass-ceramics

2019 ◽  
Vol 33 (09) ◽  
pp. 1950070 ◽  
Author(s):  
Tingnan Yan ◽  
Weijun Zhang ◽  
Haijun Mao ◽  
Xingyu Chen ◽  
Shuxin Bai
Keyword(s):  
Glass Ceramic ◽  
Glass Structure ◽  
Three Dimensional ◽  
Glass Ceramics ◽  
Degree Of Polymerization ◽  
Dimensional Structure ◽  
Molar Ratio ◽  
Sintering Behavior ◽  
The Fourier Transform ◽  
Sintering Shrinkage

We investigate the effect of CaO/SiO2 (molar ratio) and B2O3 content on the structure and sintering contraction behaviors of Calcium borosilicate (CaO–B2O3–SiO2, CBS) glass-ceramic through the dilatometer and the Fourier transform infrared (FTIR) spectroscopy. The results show that the sintering-shrinkage of CBS glass-ceramics is promoted dramatically with the increase of CaO/SiO2 to 1.14, and then keeps nearly constant as the CaO/SiO2 further increases. This phenomenon is correlated with the degree of polymerization (DOP) of the Si–O network structure modulated by the CaO/SiO2, additionally, two sintering shrinkage peaks, corresponding to two-step depolymerization, are detected in the sintering-shrinkage curves of the CBS glass-ceramic as the B2O3 content is elevated to 13.6 mol%. Meanwhile, the shrinking rate of CBS glass-ceramics is increased from 8 × 10[Formula: see text] to 37 × 10[Formula: see text] min[Formula: see text] and the softening point is decreased from 736[Formula: see text]C to 691[Formula: see text]C with the increase of B2O3 content from 6.8 to 20.8 mol⋅%. This is due to the introduction of BO3 trihedral into Si–O–Si three-dimensional structure, which greatly reduces the uniformity and symmetry of the networks, inducing the decrease of the strength for the whole Si–O–Si network structures. The results obtained in this paper reveal the relationship between the glass structure and sintering behavior of the CBS glass-ceramic, which gives an avenue to improve its physical properties.

Diffraction by crystals

2002 ◽  
Author(s):  
David Blow
Keyword(s):  
Fourier Transform ◽  
Three Dimensional ◽  
Incident Beam ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Dimensional Structure ◽  
Angle Of Incidence ◽  
X Ray ◽  
Max Von Laue ◽  
The Fourier Transform

In Chapter 4 many two-dimensional examples were shown, in which a diffraction pattern represents the Fourier transform of the scattering object. When a diffracting object is three-dimensional, a new effect arises. In diffraction by a repetitive object, rays are scattered in many directions. Each unit of the lattice scatters, but a diffracted beam arises only if the scattered rays from each unit are all in phase. Otherwise the scattering from one unit is cancelled out by another. In two dimensions, there is always a direction where the scattered rays are in phase for any order of diffraction (just as shown for a one-dimensional scatterer in Fig. 4.1). In three dimensions, it is only possible for all the points of a lattice to scatter in phase if the crystal is correctly oriented in the incident beam. The amplitudes and phases of all the scattered beams from a three-dimensional crystal still provide the Fourier transform of the three-dimensional structure. But when a crystal is at a particular angular orientation to the X-ray beam, the scattering of a monochromatic beam provides only a tiny sample of the total Fourier transform of its structure. In the next section, we are going to find what is needed to allow a diffracted beam to be generated. We shall follow a treatment invented by Lawrence Bragg in 1913. Max von Laue, who discovered X-ray diffraction in 1912, used a different scheme of analysis; and Paul Ewald introduced a new way of looking at it in 1921. These three methods are referred to as the Laue equations, Bragg’s law and the Ewald construction, and they give identical results. All three are described in many crystallographic text books. Bragg’s method is straightforward, understandable, and suffices for present needs. I had heard J.J. Thomson lecture about…X-rays as very short pulses of radiation. I worked out that such pulses…should be reflected at any angle of incidence by the sheets of atoms in the crystal as if these sheets were mirrors.…It remained to explain why certain of the atomic mirrors in the zinc blende [ZnS] crystal reflected more powerfully than others.

scholarly journals Three-dimensional structure of actin filaments and of an actin gel made with actin-binding protein.

1983 ◽  
Vol 96 (5) ◽  
pp. 1400-1413 ◽  
Author(s):  
R Niederman ◽  
P C Amrein ◽  
J Hartwig
Keyword(s):  
Actin Filaments ◽  
Binding Protein ◽  
Three Dimensional ◽  
Actin Binding ◽  
Dimensional Structure ◽  
Molar Ratio ◽  
Computer Assisted ◽  
Three Dimensional Structure ◽  
Actin Binding Protein ◽  
Critical Point Drying

Purified muscle actin and mixtures of actin and actin-binding protein were examined in the transmission electron microscope after fixation, critical point drying, and rotary shadowing. The three-dimensional structure of the protein assemblies was analyzed by a computer-assisted graphic analysis applicable to generalized filament networks. This analysis yielded information concerning the frequency of filament intersections, the filament length between these intersections, the angle at which filaments branch at these intersections, and the concentration of filaments within a defined volume. Purified actin at a concentration of 1 mg/ml assembled into a uniform mass of long filaments which overlap at random angles between 0 degrees and 90 degrees. Actin in the presence of macrophage actin-binding protein assembled into short, straight filaments, organized in a perpendicular branching network. The distance between branch points was inversely related to the molar ratio of actin-binding protein to actin. This distance was what would be predicted if actin filaments grew at right angles off of nucleation sites on the two ends of actin-binding protein dimers, and then annealed. The results suggest that actin in combination with actin-binding protein self-assembles to form a three-dimensional network resembling the peripheral cytoskeleton of motile cells.

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.

scholarly journals Crystallization Kinetics and Structural Properties of the 45S5 Bioactive Glass and Glass-Ceramic Fiber Doped with Eu3+

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1281 ◽  
Author(s):  
Agata Baranowska ◽  
Magdalena Leśniak ◽  
Marcin Kochanowicz ◽  
Jacek Żmojda ◽  
Piotr Miluski ◽  
...  
Keyword(s):  
Bioactive Glass ◽  
Crystallization Kinetics ◽  
Glass Ceramic ◽  
Structural Changes ◽  
Glass Fibers ◽  
Glass Structure ◽  
Glass Ceramics ◽  
Luminescent Properties ◽  
Ceramic Fiber ◽  
Scanning Calorimetry

An investigation of the crystallization kinetics of 45S5 Bioglass® using differential scanning calorimetry is presented in this paper. Thermal analysis was performed using the Friedman method. The activation energy and the Avrami index were calculated. The glass samples were subjected to additional controlled heat treatment at 620 °C in order to obtain bioactive glass-ceramics with enhanced mechanical properties. X-ray powder diffraction (XRD) measurements indicated the formation of the glass-ceramic structures of three cyclosilicates: Na4Ca4(Si6O18) or Na6Ca3(Si6O18) or Na16Ca4(Si12O36). Based on middle infrared region (MIR) results, it can be concluded that the crystalline phase present in the tested materials was Na6Ca3(Si6O18) (combeite). Material was doped with Eu3+ ions, which act as a spectroscopic probe for monitoring the structural changes in the glass matrix. The decreasing value of the fluorescence intensity radio parameter indicated symmetry around the europium ions and, thus, the arrangement of the glass structure. The bioactive properties of the examined glass-ceramics were also determined. The bioactive glass fibers doped with Eu3+ were manufactured using two different methods. Its structural and luminescent properties were examined.

scholarly journals The Crystallization Behaviors of SiO2-Al2O3-CaO-MgO-TiO2 Glass-Ceramic Systems

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 794
Author(s):  
Feifei Lai ◽  
Mei Leng ◽  
Jiangling Li ◽  
Qingcai Liu
Keyword(s):  
Mechanical Properties ◽  
Glass Ceramic ◽  
Crystalline Phase ◽  
Three Dimensional ◽  
Glass Ceramics ◽  
Exothermic Peak ◽  
Obvious Effect ◽  
Prepared Glass ◽  
Main Crystalline Phase ◽  
Hardness Values

To evaluate the crystallization behavior of Ti-bearing blast furnace slag-based glass ceramics, SiO2-Al2O3-CaO-MgO-TiO2 systems with various TiO2 were investigated. The crystallization process and mechanical properties were analyzed. The results show that with TiO2 increasing, exothermic peak temperature (Tp) decreases, and the crystallization is promoted by the introduction of TiO2. A small amount of TiO2 (≤4%) addition can significantly promote crystallization, and when TiO2 continues to increase, the crystallization is decreased slightly. The Avrami parameter (n) of all samples is less than 4, indicating that in prepared glass-ceramics, it is hard to achieve three-dimensional crystal growth. The main crystalline phase is akermanite–gehlenite. The addition of TiO2 has no obvious effect on the type of main crystalline phase. The prepared glass-ceramic with 4% TiO2 show good mechanical properties with the hardness values of 542.67 MPa. The recommended content of TiO2 is 4% for preparing glass-ceramics.

scholarly journals Unraveling the Role of Drug-Lipid Interactions in NSAIDs-Induced Cardiotoxicity

Membranes ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 24
Author(s):  
Catarina Pereira-Leite ◽  
Marina Figueiredo ◽  
Kinga Burdach ◽  
Cláudia Nunes ◽  
Salette Reis
Keyword(s):  
Lipid Bilayers ◽  
Three Dimensional ◽  
Model Systems ◽  
Dimensional Structure ◽  
Molar Ratio ◽  
Similar Action ◽  
Lipid Interactions ◽  
Action Mechanisms ◽  
X Ray Scattering

Cardiovascular (CV) toxicity is nowadays recognized as a class effect of non-aspirin nonsteroidal anti-inflammatory drugs (NSAIDs). However, their mechanisms of cardiotoxicity are not yet well understood, since different compounds with similar action mechanisms exhibit distinct cardiotoxicity. For instance, diclofenac (DIC) is among the most cardiotoxic compounds, while naproxen (NAP) is associated with low CV risk. In this sense, this study aimed to unravel the role of drug-lipid interactions in NSAIDs-induced cardiotoxicity. For that, DIC and NAP interactions with lipid bilayers as model systems of cell and mitochondrial membranes were characterized by derivative spectrophotometry, fluorometric leakage assays, and synchrotron X-ray scattering. Both DIC and NAP were found to have the ability to permeabilize the membrane models, as well as to alter the bilayers’ structure. The NSAIDs-induced modifications were dependent on the lipid composition of the membrane model, the three-dimensional structure of the drug, as well as the drug:lipid molar ratio tested. Altogether, this work supports the hypothesis that NSAIDs-lipid interactions, in particular at the mitochondrial level, may be another key step among the mechanisms underlying NSAIDs-induced cardiotoxicity.

The Effect of SiO2, TiO2, and B2O3 on the Crystallization of Glass-Ceramics Glaze Properties

2016 ◽  
Vol 690 ◽  
pp. 206-211 ◽  
Author(s):  
Lada Punsukumtana ◽  
Sansanee Rugthaicharoencheep ◽  
Usuma Naknikham ◽  
Netnapha Suphanam
Keyword(s):  
Vickers Hardness ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
High Hardness ◽  
Sintering Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceramic Glaze ◽  
Industry Applications ◽  
Firing History

The feasibility of developing glass-ceramic glaze in the system KNaO-CaO-MgO-ZnO with a variation in the composition of SiO2, TiO2, and B2O3 was studied. The SiO2, TiO2, and B2O3 were varied in the amount of 2.25-1.50, 0.001-0.10, and 0-0.1 molar equivalents respectively. The samples were one fired at 1180°C or double fired by reheat at the crystallization temperature for 10 minutes. The gloss, sintering behavior, phase, microstucture, and hardness, and were examined by glossmeter, side-view hot stage microscope, X-ray diffraction, SEM, and Vickers hardness respectively. The results showed the importance effect of SiO2, TiO2, and B2O3 on the glaze crystallization ability and its properties. At the fix value of Al2O3 at 0.24 molar equivalents and with the 0.001-0.10 molar equivalents of TiO2, lower the SiO2 content to 1.50 molar equivalents increased the glaze crystallization potential. An increase in the B2O3 to 0.1 molar equivalents suppressed the potential of glaze crystallization. The phases of samples were amorphous or composed of silicon dioxide and diopside as the main phases depending on the glaze composition and the firing history. In this study, the glaze appearances transparent to opaque and varied from gloss to matte with the specular gloss values between 23-100 GU. All samples appeared to have high Vickers hardness value in the range of 553-644. The crystallization decreased the gloss but increased the hardness value for the 2.25 molar equivalents SiO2 glaze. Finally, a composition with high hardness and high gloss was identified and its properties was also presented. These results suggested the limitation and the potential for applying this glass-ceramic glaze system to industry applications.

Bioactive Glass-Ceramic Porous Sinters

2006 ◽  
Vol 49 ◽  
pp. 103-108
Author(s):  
R. Sindut ◽  
Katarzyna Cholewa-Kowalska ◽  
Maria Łączka
Keyword(s):  
Bioactive Glass ◽  
Glass Ceramic ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Diffraction Method ◽  
Thin Layers ◽  
Molar Ratio ◽  
Chemical Compositions ◽  
Bioactive Materials

Bioglasses and bioactive glass-ceramics have found increasingly wide application in medicine and dentistry. Using sol-gel method, is possible to obtain glass and glass-ceramic bioactive materials of new generation, characterized the higher bioactivity than melted bioglasses. These materials can be produced in various final forms, as powders, thin layers on different base and porous sinters. Production of porous bioactive sinters from gel-derived powders is a new problem and the parameters controlling this process are not recognized yet. The aim of the study was to obtain porous bioactive sinters from gel-derived powders of the SiO2-CaO-P2O5 system of four various chemical compositions (S2, II, I, A2) and the characterization of properties of these new materials. The starting powders differ from each other in the content of the basic components, at the molar ratio of CaO to SiO2 equals 0.2-1.35. To obtain the porous sinters a method of burning additions and deposition of the casting slip on the polymeric sponge was used. Sintering was realized in several stages, at the maximal temperature 1200oC. By selecting appropriate conditions of sintering, a durable material of high open porosity up to 77 % was obtained. Its porous structure was characterized by a prevailing number of small micropores of similar dimensions, uniformly distributed in the material. The phase composition of obtained sinters was determined by the X-ray diffraction method. All sinters represented glass-ceramic materials with apatite, cristoballite and calcium silicates as a main crystalline phases. In order to preliminary determination bioactivity of obtained sinters, test in vitro in simulated body fluid SBF was conducted. It was found that hydroxyapatite formation on the sinter surface occurs only in the case of biomaterials of highest calcium concentration.

scholarly journals Fiber fines for fabricating lignocellulose films and the effect of lignin

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 4417-4433
Author(s):  
Mohammad Pourjafar ◽  
Amir Khosravani ◽  
Rabi Behrooz
Keyword(s):  
Lignin Content ◽  
Three Dimensional ◽  
Strength Properties ◽  
Degree Of Polymerization ◽  
Dimensional Structure ◽  
Film Properties ◽  
Imidazolium Chloride ◽  
Low Degree ◽  
Rapid Dissolution ◽  
Fiber Processing

Excess lignocellulose fines in some fiber processing mills cause issues and hurt product quality. To use this type of biomaterial as a resource, surplus fines can be separated and dissolved with solvents for further transformation. Therefore, 1-butyl 3-methyl imidazolium chloride ionic liquid (IL) was used as a powerful green solvent for a rapid dissolution process. However, a low degree of polymerization (DP) of the cellulose in fines and the effects of lignin content and its structure on the process and film properties are controversial subjects. This study demonstrated that the three dimensional structure of lignin did not permit the raw bagasse fines (prior to pulping) to dissolve in the IL even after several hours. However, following decomposition of the lignin structure by pulping, the fiber fines were readily dissolved. Further, all the fabricated films from the fiber fines exhibited satisfactory strength properties, despite the fact that the cellulose had a low DP. The films from bleached fiber fines showed higher tensile strength than those containing lignin, although the cellulose chain was longer and had a higher DP for the latter. Lignin resulted in reduced transparency, and higher absorption of ultraviolet radiations, but it did not affect the surface roughness of the films.

scholarly journals Crystallization Behavior and Microstructure of Bio Glass-Ceramic System

2013 ◽  
Vol 19 ◽  
pp. 58-68 ◽  
Author(s):  
Behzad Mehdikhani ◽  
Gholam Hossein Borhani
Keyword(s):  
Glass Ceramic ◽  
Crystallization Behavior ◽  
Glass Ceramics ◽  
Al2o3 Content ◽  
Sintering Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceramic Samples ◽  
Molar Percent ◽  
Glass Compositions

The effects of Al2O3 on the crystallization behavior of glass compositions in the Na2O-CaO-SiO2 system were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Effect of Al2O3 content on the mechanical, density, phase formation and microstructures of Na2O-CaO–P2O5–Al2O3-SiO2 glass ceramics were studied. Thermal parameters of each glass were studied by DTA. The density of the glass ceramic samples was measured by Archimedes’ method. It was found that the glass–ceramic containing 2.0 molar percent Al2O3 had desirable sintering behavior and reached to an acceptable density. Phase investigation and micro structural study were performed by XRD and SEM, respectively.

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