scholarly journals Synthesis and Formation Process of a Typical Doped Solid-Solution Ye’elimite (Ca3.8Na0.2Al5.6Fe0.2Si0.2SO16): Experiments and Kinetic Analysis

2021 ◽  
Vol 11 (17) ◽  
pp. 8015
Author(s):  
Jiuye Zhao ◽  
Jiazhi Huang ◽  
Chunyang Yu ◽  
Chunyi Cui
Keyword(s):  
Solid Solution ◽  
Calcium Aluminate ◽  
Formation Process ◽  
Three Dimensional ◽  
Correlation Coefficients ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Promising Alternative ◽  
Calcium Sulfoaluminate ◽  
Intermediate Phases

Ye’elimite is a dominant phase in calcium sulfoaluminate cement, which is a promising alternative type of cementitious binder. Ca3.8Na0.2Al5.6Fe0.2Si0.2SO16 (abbreviated as ss-C4A3$) is a kind of typical doped solid-solution ye’elimite. In this study, the formation process of ss-C4A3$ was investigated. Clinkers of ss-C4A3$ were sintered at various temperatures for different holding times. X-ray diffraction tests and Rietveld quantitative phase analysis were conducted to determine the phase compositions of the clinkers. Meanwhile, the formation process of ss-C4A3$ was analyzed by kinetic theory. The results show that solid reactions between intermediate phases (calcium aluminate phases) and anhydrite mainly resulted in the formation of ss-C4A3$. In the conditions of 1150–1250 °C, ss-C4A3$ tended to be formed and stable until 4 h. However, when the sintering temperature was 1300 °C, the ss-C4A3$ decreased to generate calcium aluminate phases after 2 h. Compared to other kinetic models, the three-dimensional diffusion model mostly conformed with the formation process of ss-C4A3$, and the fitting results obtained by the Jander model exhibited the highest correlation coefficients. The activation energy of ss-C4A3$ formation equaled 285.6 kJ/mol, which was smaller than that of stoichiometric ye’elimite.

The modulated structure of the calcium aluminate Ca6(AlO2)12·Bi2O3

2010 ◽  
Vol 66 (6) ◽  
pp. 585-593 ◽  
Author(s):  
O. Pérez ◽  
S. Malo ◽  
M. Hervieu
Keyword(s):  
Single Crystal ◽  
Calcium Aluminate ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Electron Pairs ◽  
Modulated Structure ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Superspace Formalism ◽  
Single Crystal Analysis

Bismuth calcium aluminate, Bi2Ca6Al12O27, has been prepared as a ceramic and a single crystal. Analysis of reciprocal space using both electron and X-ray diffraction show an R-centred hexagonal unit cell: a = b = 17.3892 (4), c = 6.986 (1) Å. Additional weak reflections are observed; they require the introduction of a modulation wavevector q = 0.0453 (2)c* for indexing. The modulated structure has been solved using the superspace formalism [superspace group X\overline{3}(00\gamma)0]. A framework of corner-sharing AlO4 tetrahedra forms corrugated sixfold rings and uncommon triple rings. The Ca2+ cations exhibit an eightfold coordination sphere; edge-sharing CaO8 polyhedra form intertwinned zigzagging rows along c creating a three-dimensional net. Bi atoms are located in large hexagonal tunnels parallel to c and form Bi2O3 pairs, which adopt a trigonal bipyramidal configuration. The 6s 2 lone-electron pairs (Lp) point along c, in the opposite direction to the three Bi—O strong bonds to form two BiO3Lp tetrahedra with a common base. Different orientations of the Bi2O3Lp2 pairs, rotated by 60° around c, are observed. Their stacking modes in each of the hexagonal tunnels are described. The sequence of the stacking varies along c in each of the tunnels.

Effects of V2O5 on the synthesis of Ba2Ti9O20 powders

2005 ◽  
Vol 20 (10) ◽  
pp. 2741-2744 ◽  
Author(s):  
Huixing Lin ◽  
Wei Chen ◽  
Lan Luo
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Scanning Electron Microscopy ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Eutectic Liquid ◽  
X Ray ◽  
Intermediate Phases ◽  
Phase Pure ◽  
Scanning Electron

Phase-pure Ba2Ti9O20 powders were made by doping 3 wt% of V2O5 to a Ba:Ti = 2:9 molar composition, and the effects of the dopant on the phase formation were investigated. The study shows that BaTiO3, BaTi2O5, and BaTi4O9 were the intermediate phases before the formation of Ba2Ti9O20 for samples with or without V2O5. However, with V2O5 doping, the temperature at which Ba2Ti9O20 occurred were lowered from 1150 to 1050 °C and single phase Ba2Ti9O20 powders was easily obtained at 1150 °C for 2 h. Microstructure of the powders was examined by field emission scanning electron microscopy. No evidence of V2O5–Ba2Ti9O20 solid-solution was found by x-ray diffraction and energy-dispersive spectroscopy. The benefit of V2O5 to facilitate the Ba2Ti9O20 synthesis is most probably due to a vanadium-containing eutectic liquid phase which accelerates the migration of reactant species.

Forming Mechanism of Dy2Ce2O7 Ceramic for Thermal Barrier Coatings

2010 ◽  
Vol 105-106 ◽  
pp. 383-385
Author(s):  
Hong Song Zhang ◽  
Ren Xi Hu ◽  
Qiang Xu
Keyword(s):  
Solid Solution ◽  
Diffraction Method ◽  
Thermal Barrier ◽  
X Ray Diffraction ◽  
Solid Reaction ◽  
X Ray ◽  
Forming Mechanism ◽  
Whole Process ◽  
Intermediate Phases ◽  
Solution Reaction

The forming mechanism of Dy2Ce2O7 prepared by solid reaction using CeO2 and Dy2O3 as reactants was analyzed by X-ray diffraction method. It is indicated that there is almost no solid solution reaction between Dy2O3 and CeO2 before 1300°C, the Dy3+ cations enter the crystal lattice of CeO2 and substitute sites of Ce4+ cations in the range between 1300°C and 1400°C which resulted in the formation of Dy2O3-CeO2 solid solution. The Dy2O3-CeO2 solid solution transformed gradually into Dy2Ce2O7 after 1400°C and pure Dy2Ce2O7 can be obtained at 1500°C. No other intermediate phases were found in the whole process.

Rietveld refinements of a new solid solution Ba(3−x)Srx(PO4)2 (0≤x≤3)

2003 ◽  
Vol 18 (2) ◽  
pp. 122-127 ◽  
Author(s):  
B. Manoun ◽  
L. Popović ◽  
D. De Waal ◽  
S. M. C. Verryn
Keyword(s):  
Solid Solution ◽  
Solid State ◽  
Solid State Reaction ◽  
Continuous Solid Solution ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Final Temperature ◽  
Hexagonal System ◽  
Rietveld Refinements ◽  
X Ray

Ba(3−x)Srx(PO4)2 orthophosphates (0≤x≤3) have been prepared by solid state reaction. The final temperature was 1000°C. The X-ray diffraction analyses show the existence of a continuous solid solution. Ba(3−x)Srx(PO4)2 orthophosphates (0≤x≤3) crystallize in the hexagonal system with the space group R3m. Their structure is based on a three-dimensional framework constructed of infinite layers of Ba1/Sr1O12 linked and parallel to infinite layers of Ba2/Sr2O10 polyhedra and PO4 tetrahedra.

Phase Relation and Microstructure of NbCr2 Laves Intermetallics in Ternary Nb-Cr-X Alloy Systems

1996 ◽  
Vol 460 ◽  
Author(s):  
M. Yoshida ◽  
T. Takasugi
Keyword(s):  
Solid Solution ◽  
Alloy System ◽  
X Ray Diffraction ◽  
Laves Phases ◽  
Characteristic Structure ◽  
X Ray ◽  
Intermediate Phases ◽  
Transmission Electron ◽  
Solid Solution Range ◽  
Alloy Systems

ABSTRACTThe isothermal phase diagrams of ternary alloy systems Nb-Cr-V and Nb-Cr-Mo are determined by metallography, X-ray diffraction (XRD) and transmission electron microscopy (TEM) equipped with energy dispersive X-ray (EDX). In two alloy systems, the C15 NbCr2 Laves phases are equilibrated directly with bcc solid solution without forming any intermediate phases. Relatively large amount of ternary elements V and Mo are soluble in the C15 NbCr2 Laves phases. It is shown that the C15 Laves phases extend along directions so that V occupies Cr site while Mo occupies Nb site. Also, characteristic structure containing micro twins and stacking faults is observed in the C15 Laves phase alloyed with Mo. Bcc phase has a wider solid solution range in the X(=V and Mo)-rich side than the Nb-rich and Cr-rich sides. A variety of duplex microstructures are observed depending on alloy system and alloy composition.

scholarly journals Effect of the Cooling Regime on the Mineralogy and Reactivity of Belite-Sulfoaluminate Clinkers

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 910
Author(s):  
Sabina Dolenec ◽  
Katarina Šter ◽  
Maruša Borštnar ◽  
Klara Nagode ◽  
Andrej Ipavec ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Raw Materials ◽  
Isothermal Calorimetry ◽  
Bottom Ash ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Cooling Regime ◽  
X Ray ◽  
Calcium Sulfoaluminate ◽  
Size And Morphology

This study investigated the influence of different cooling regimes on the microstructure and consequent reactivity of belite-sulfoaluminate clinkers. The cement clinkers were synthesized by incorporating secondary raw materials, such as titanogypsum and bottom ash, to the natural raw materials. Clinker phases were determined by Rietveld quantitative phase analysis, while the distribution morphology and the incorporation of substitute ions in the phases were characterized by scanning electron microscopy using energy-dispersive X-ray spectroscopy (SEM/EDS). Clinker reactivity was studied using isothermal calorimetry and was additionally investigated through compressive strength, which was determined for the cement prepared from the synthesized clinkers. X-ray diffraction analysis showed that, as well as the three main phases (belite, calcium sulfoaluminate, and ferrite), the clinkers contained additional minor phases (mayenite, gehlenite, arkanite, periclase, and perovskite), the ratios of which varied according to the cooling regime utilized. Microscopic observations indicated that the cooling regime also influenced the crystal size and morphology of the main phases, which consequently affected clinker reactivity. Furthermore, a smaller amount of substitute elements was incorporated in the main phases when cooling was slowed. Results showed that, in comparison to clinkers cooled at slower rates, air quenched clinkers reacted faster and exhibited a higher compressive strength at 7 days.

Towards three-dimensional quantitative reconstruction of cement microstructure by X-ray diffraction microtomography

2011 ◽  
Vol 44 (2) ◽  
pp. 272-280 ◽  
Author(s):  
Luca Valentini ◽  
Maria Chiara Dalconi ◽  
Matteo Parisatto ◽  
Giuseppe Cruciani ◽  
Gilberto Artioli
Keyword(s):  
Cement Paste ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Quantitative Information ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Quantitative Characterization ◽  
X Ray ◽  
Non Invasive ◽  
Cement Based Materials

Quantitative characterization of the microstructure of cement-based materials is of fundamental importance for assessing the performance and durability of the final products. However, accessing the three-dimensional microstructural information of hydrating cement pastes without introducing any perturbation is not trivial. Recently, a novel non-invasive method based on X-ray diffraction computed microtomography (XRD-CT) has been applied to cement-based materials, with the aim of describing the three-dimensional spatial distribution of selected phases during the hydration of the cement paste. This paper illustrates a method based on XRD-CT, combined with Rietveld-based quantitative phase analysis and image processing, which provides quantitative information relative to the distribution of the various phases present in the studied samples. In particular, it is shown how this method allows the estimation of the local volume fraction of the phase ettringite within a hydrating cement paste, and construction of a three-dimensional distribution map. Application of this method to the various constituents of a cementitious material, or, more generally, of a composite polycrystalline material, may provide a non-invasive tool for three-dimensional microstructural quantitative characterization.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Electron Microscopy of Cytoplasmic Contractile Proteins

1978 ◽  
Vol 36 (3) ◽  
pp. 606-614 ◽  
Author(s):  
T.D. Pollard ◽  
P. Maupin
Keyword(s):  
Electron Microscopy ◽  
Actin Filaments ◽  
Three Dimensional ◽  
Uranyl Acetate ◽  
Contractile Proteins ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
Cytoplasmic Matrix ◽  
Computer Image Processing ◽  
Nonmuscle Cells

In this paper we review some of the contributions that electron microscopy has made to the analysis of actin and myosin from nonmuscle cells. We place particular emphasis upon the limitations of the ultrastructural techniques used to study these cytoplasmic contractile proteins, because it is not widely recognized how difficult it is to preserve these elements of the cytoplasmic matrix for electron microscopy. The structure of actin filaments is well preserved for electron microscope observation by negative staining with uranyl acetate (Figure 1). In fact, to a resolution of about 3nm the three-dimensional structure of actin filaments determined by computer image processing of electron micrographs of negatively stained specimens (Moore et al., 1970) is indistinguishable from the structure revealed by X-ray diffraction of living muscle.

Electron Microscopy/Diffraction Study of the Ternary Mn-Er-S System

1990 ◽  
Vol 48 (1) ◽  
pp. 76-77
Author(s):  
A. R. Landa Canovas ◽  
L.C. Otero Diaz ◽  
T. White ◽  
B.G. Hyde
Keyword(s):  
Electron Microscopy ◽  
Gas Flow ◽  
Graphite Crucible ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Alumina Crucible ◽  
X Ray ◽  
Intermediate Phases ◽  
Twin Band ◽  
Ar Gas

X-Ray diffraction revealed two intermediate phases in the system MnS+Er2S3,:MnEr2S4= MnS.Er2S3, and MnEr4S7= MnS.2Er2S3. Their structures may be described as NaCl type, chemically twinned at the unit cell level, and isostructural with CaTi2O4, and Y5S7 respectively; i.e. {l13} NaCl twin band widths are (4,4) and (4,3).The present study was to search for structurally-related (twinned B.) structures and or possible disorder, using the more sensitive and appropiate technigue of electron microscopy/diffraction.A sample with nominal composition MnEr2S4 was made by heating Mn3O4 and Er2O3 in a graphite crucible and a 5% H2S in Ar gas flow at 1500°C for 4 hours. A small amount of this material was thenannealed, in an alumina crucible, contained in sealed evacuated silica tube, for 24 days at 1100°C. Both samples were studied by X-ray powder diffraction, and in JEOL 2000 FX and 4000 EX microscopes.

Sign in / Sign up

Export Citation Format

Share Document