Effect of zeolitization on the volume-change behaviour of kaolinitic soils

2006 ◽  
Vol 43 (9) ◽  
pp. 969-978 ◽  
Author(s):  
P V Sivapullaiah ◽  
M Manju
Keyword(s):  
Volume Change ◽  
Alkali Solution ◽  
Time Lags ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alkali Solutions ◽  
Zeolite Formation ◽  
Interaction Period

An attempt has been made to study the effect of zeolite formation on the volume-change behaviour of kaolinitic soil. This is studied in terms of two criteria, namely concentration and period of interaction. Conventional consolidation tests have been carried out to determine the extent of change in swell and compressibility of kaolinitic soils remoulded with water and inundated with an alkali solution. It was observed that abnormal swell occurs during unloading when specimens were inundated with a 4N alkali solution. While allowing a longer interaction period at 6.25 kPa, it was found that swelling in kaolinitic soils is induced after time lags of 30 and 15 days on inundation with 1N and 4N alkali solutions, respectively. Equilibrium is reached after 50–70 days in kaolinitic soils, however, and loading was undertaken later. A 16% swelling was observed in kaolinitic soils when inundated with a 4N alkali solution, indicating that zeolitization of kaolinite results in swelling at the seating load provided the period of interaction is sufficient. X-ray diffraction studies confirm the formation of zeolite.Key words: alkali, consolidation, kaolinite, swelling, X-ray diffraction, zeolite.

Hydroxyapatite Precursor Phases Identification by X-Ray Diffraction Using Synchrotron Radiation

2007 ◽  
Vol 330-332 ◽  
pp. 115-118 ◽  
Author(s):  
Silvia R. A. Santos ◽  
Antonella M. Rossi ◽  
Marcelo Henrique Prado da Silva
Keyword(s):  
Synchrotron Radiation ◽  
Diffraction Analysis ◽  
Intermediate Phase ◽  
Octacalcium Phosphate ◽  
Alkali Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Intensity ◽  
Synchrotron Light ◽  
Precursor Phases

The present study presents the relevance of X-ray diffraction analysis using synchrotron light in the identification of phases with low intensity peaks. Niobium sheets were coated with monetite and then converted to hydroxyapatite in an alkali solution. Octacalcium phosphate was identified as an intermediate phase in the conversion monetite-hydroxyapatite.

scholarly journals Effect of H2O Activity on Zeolite Formation

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4780
Author(s):  
Claudia Belviso ◽  
Francesco Cavalcante
Keyword(s):  
Liquid Nitrogen ◽  
Sodium Aluminate ◽  
Drying Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lta Zeolite ◽  
Zeolite Formation ◽  
Silica Alumina ◽  
Over Time ◽  
Scanning Electron

In an effort to understand the effects of H2O activity on zeolite formation, we have synthesized LTA zeolite using a combination of freezing processes and varying drying temperatures. Sodium aluminate and sodium silicate were used to form LTA zeolite, according to the IZA (International Zeolite Association) protocol. The synthesis steps were modified by adding the precursor frozen process by a rapid liquid nitrogen (−196 °C) treatment or slow conventional freezer treatment (−20 °C). The samples were subsequently sonicated and then dried at 80 °C or 40 °C. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed on the samples immediately after the drying process as well as after 2 weeks and 1 month of aging the solid products. The results indicated that LTA zeolite does not form. The silica-alumina precursor after both freezing processes and after being dried at 80 °C showed the presence of sodalite displaying stable behavior over time. Both sets of samples dried at 40 °C and did not show the presence of zeolite immediately after the drying process. However, after 2 weeks, the liquid nitrogen–frozen precursor was characterized by the presence of EMT whereas zeolites never formed in the −20 °C samples. These results suggest that freezing processes differently control the H2O activity during the drying and aging processes in the solid state. Thus, although the precursor chemical composition is the same, the type of zeolite formed is different.

scholarly journals Strength and Volume Change Characteristics of Clayey Soils: Performance Evaluation of Enzymes

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 52
Author(s):  
Tanveer Ahmed Khan ◽  
Mohd Raihan Taha ◽  
Mudasser Muneer Khan ◽  
Syyed Adnan Raheel Shah ◽  
Muhammad Asif Aslam ◽  
...  
Keyword(s):  
Volume Change ◽  
Unconfined Compressive Strength ◽  
Optimum Moisture Content ◽  
Soil Samples ◽  
Residual Soil ◽  
Clayey Soils ◽  
X Ray Diffraction ◽  
Treated Soil ◽  
X Ray ◽  
Change Characteristics

This study was conducted to evaluate the strength and volume change characteristics of a sedimentary residual soil mixed with bentonite (S1) when treated with three different enzymes. In addition, three reference clays including bentonite, illite, and kaolinite were also treated with enzymes to study the effect on their strength characteristics. Soil samples prepared at the optimum moisture content (OMC) were sealed and cured for four months. After curing, reference clays were tested for unconfined compressive strength (UCS). For swell tests, the S1 soil samples were placed on porous stones, which were immersed in water to allow capillary soaking of the samples. S1 samples were allowed to dry at ambient temperature for shrinkage test until the rate of reduction in volume became negligible. On completion of swell tests, the samples were tested for UCS to determine the decrease in strength due to saturation. No increase in strength and decrease in volume change were observed for any of the enzymes and dosages. Field Emission Scanning Electron Microscope (FESEM) showed some dense packing of particles for treated samples, whereas X-ray diffraction (XRD) did not reveal any change; in fact, the pattern for untreated and treated soil samples were indistinguishable.

scholarly journals Spherical Sb Core/Nb2O5-C Double-Shell Structured Composite as an Anode Material for Li Secondary Batteries

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1999
Author(s):  
Hyungeun Seo ◽  
Kyungbae Kim ◽  
Jae-Hun Kim
Keyword(s):  
Volume Change ◽  
Photoelectron Spectroscopy ◽  
Active Material ◽  
High Capacity ◽  
Reversible Capacity ◽  
Cycle Performance ◽  
Core Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Improved Performance

Antimony (Sb)-based materials are considered to be attractive for use in Li secondary battery anodes because of their high capacity. However, their huge volume change during Li insertion-extraction cycling limits their cycle performance. The Sb-active material can be combined with intercalation-based active materials to address these issues. In this study, spherical Sb core/Nb2O5 shell structured composite materials were synthesized through a simple solvothermal process and a carbon coating was simultaneously added during heat treatment using a naphthalene precursor. The resulting double-shelled materials were characterized with X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and electron microscopy. The electrochemical test results showed that a reversible capacity of more than 450 mAh g−1 was retained after 100 cycles. This improved performance is ascribed to the double-shelled structure. The large volume change of the nano-sized Sb core material was alleviated by the double-shelled structure, which consisted of crystalline orthorhombic Nb2O5 and amorphous carbon. The shell materials also aided rapid charge transport.

Thermal expansion of corium prepared from UO2 and Zircaloy-2

2012 ◽  
Vol 1444 ◽  
Author(s):  
Shun Hirooka ◽  
Masatoshi Akashi ◽  
Teppei Uchida ◽  
Kyoichi Morimoto ◽  
Masato Kato
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Volume Change ◽  
Thermal Vibration ◽  
X Ray Diffraction ◽  
Volume Changes ◽  
X Ray ◽  
Content Ratio ◽  
Diffraction Patterns ◽  
Ar Gas

ABSTRACTIn this study, sintered pellets were prepared from Zircaloy-2 oxide and UO2 as a parameter of content ratio (Zr contents were 0, 24.3, 49.0, 73.4, and 97.9 at% in metal). The sintered pellets were heated in 5%H2/Ar gas. UO2 pellets underwent simple thermal expansion caused by thermal vibration while Zircaloy-2 oxide pellets underwent thermal expansion and volume change with phase transformation. Finally, the 24.3, 49.0, and 73.5 at%Zr-UO2 pellet specimens showed both phenomena. However, phase transformation temperatures were lower than that of Zircaloy-2 oxide, and volume changes were much smaller. X-ray diffraction patterns obtained after thermal expansion measurements showed that the 24.3 at%Zr-UO2 specimen contained tetragonal and cubic (Zr, U)O2 while the 73.5 at%Zr-UO2 specimen contained mainly monoclinic ZrO2.

scholarly journals Observation of Sb2S3-type post-post-perovskite in NaFeF3. Implications for ABX3 and A2X3 systems at ultrahigh pressure

2016 ◽  
Vol 80 (4) ◽  
pp. 659-674 ◽  
Author(s):  
W. A. Crichton ◽  
F. L. Bernal ◽  
J. Guignard ◽  
M. Hanfland ◽  
S. Margadonna
Keyword(s):  
High Pressure ◽  
Volume Change ◽  
Large Volume ◽  
Considerable Change ◽  
Ultrahigh Pressure ◽  
X Ray Diffraction ◽  
Concomitant Increase ◽  
X Ray ◽  
Average Bond ◽  
Crystallographic Orientations

AbstractWe describe the structures and transformations that lead to the crystallization of a post-post-perovskite of Sb2S3 type in a GdFeO3-type fluoroperovskite system at high-pressure conditions, through use of large-volume powder and single-crystal x-ray diffraction techniques. The results of this analysis gives unique access to the relative crystallographic orientations of all the polymorphs encountered (GdFeO3 type, CaIrO3 type and Sb2S3 type). We use this information to extend this description to include other calculated and observed forms that are competitive in ABX3 and A2X3 stoichiometries (e.g. α-Gd2S3 and Be3N2 types) and provide substantial information on inter-relationships between these structures. Such information is critical to the interpretation of transition mechanisms, predicting transition sequences and to the expression of directional properties in those transformed structures. The transformation from CaIrO3 type to Sb2S3 type is group-subgroup, from Cmcm with fc2a, to Pnma c5, with no observable volume change, but considerable change to the morphology of the lattice. There is a concomitant increase in coordination and average bond length compared to the post-perovskite form of NaFeF3.

High-precision face-centered cubic–hexagonal close-packed volume-change determination in high-Mn steels by X-ray diffraction data refinements

2020 ◽  
Vol 53 (1) ◽  
pp. 34-44 ◽  
Author(s):  
Florencia Malamud ◽  
Facundo Castro ◽  
Lina Maria Guerrero ◽  
Paulo La Roca ◽  
Marcos Sade ◽  
...  
Keyword(s):  
High Precision ◽  
Volume Change ◽  
Low Cycle Fatigue ◽  
Damping Capacity ◽  
Powder Materials ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hexagonal Close Packed ◽  
Face Centered

High-Mn steels attract attention because of their various technological properties. These are mainly mechanical and functional, such as the shape-memory effect, high damping capacity, high strength with simultaneous large ductility, the TRIP/TWIP (transformation- and twinning-induced plasticity) effect, low cycle fatigue and high work hardening capacity. All these phenomena are associated with the face-centered cubic (f.c.c.)–hexagonal close-packed (h.c.p.) martensitic transformation which takes place in these alloys. During this phase transition defects are introduced, mainly due to the large volume change between austenite and martensite. Knowing this volume change is key to understanding the mechanical behavior of these metallic systems. In the present article, a full-pattern refinement method is presented. The proposed method uses data obtained by means of conventional X-ray diffraction from regular bulk samples and allows a high-precision calculation of the lattice parameters of both phases, f.c.c. and h.c.p., under conditions very different from randomly oriented (powder) materials. In this work, the method is used to study the effect of chemical composition on the volume change between the two structures. By applying empirical models, the results enabled the design and fabrication of Fe–Mn-based alloys with a small volume change, showing the potential of this new tool in the search for improved materials.

Non-cellulosic structural polysaccharides in algal cell walls - III. Mannan in siphoneous green algae

1968 ◽  
Vol 169 (1015) ◽  
pp. 127-145 ◽  
Keyword(s):  
Electron Microscope ◽  
Cell Walls ◽  
Higher Plants ◽  
Algal Cell ◽  
Polarization Microscopy ◽  
X Ray Diffraction ◽  
Orthorhombic Unit Cell ◽  
X Ray ◽  
Alkali Solutions ◽  
Growth Habits

The cell walls of a number of green seaweeds, all members of the Codiaceae and the Dasy-cladaceae and including Codium and Acetabularia , are shown to contain β -1.4-linked mannan as the sole crystalline polysaccharide in the complete absence of cellulose. The X-ray diagram of the native mannan (almost identical with that of the mannan of ivory nut and of other palm-seed endosperms) has been indexed to an orthorhombic unit cell a = 7.21 Å, b (fibre axis) = 10.27 Å, c = 8.82 Å. After treatment with alkali solutions the mannan recrystallizes in a different lattice; by analogy with cellulose we propose to name this form mannan II and the native mannan, mannan I. The lamellated walls of the central siphon of some of these algae (including Dasycladus , Batophora and Cymopolia ) may be separated into two layers. X-ray diffraction analysis and polarization microscopy show that the mannan crystallites of the outer layer tend to lie transversely to the siphon axis, with some dispersion, while those in the inner layer lie longitudinally. The inner layers therefore yield good X-ray fibre diagrams from which a provisional structure of mannan I has been derived. It has proved impossible to reveal in the electron microscope, by the techniques used, the presence of true microfibrils in these plants even when the mannan is well oriented. Electron microscope images of carbon replicas reveal at most the appearance of short rodlets some 100 Å wide. The outer and inner layers resemble respectively the primary and secondary wall layers of higher plants. Some peculiar growth habits of members of the Dasycladaceae are discussed in terms of wall architecture.

Powder X-ray diffraction study of the volume change of ice VIII under high pressure

2004 ◽  
Vol 344 (1-4) ◽  
pp. 260-264 ◽  
Author(s):  
Hiroshi Yamawaki ◽  
Hiroshi Fujihisa ◽  
Mami Sakashita ◽  
Atsuko Nakayama ◽  
Katsutoshi Aoki
Keyword(s):  
High Pressure ◽  
Diffraction Study ◽  
Volume Change ◽  
X Ray Diffraction ◽  
X Ray

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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