scholarly journals Modified Natural Dolomite and Its Influence on the Production of Glycerol Carbonate: Effects of Structural and Basicity Properties

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2358
Author(s):  
Julio González-García ◽  
Lifang Chen ◽  
Omar Campuzano-Calderon ◽  
Sara Núñez-Correa ◽  
Enrique A. López-Guajardo ◽  
...  
Keyword(s):  
Formation Rate ◽  
Textural Properties ◽  
Rietveld Analysis ◽  
Glycerol Carbonate ◽  
X Ray Diffraction ◽  
Carbonate Formation ◽  
Treatment Conditions ◽  
Surface Basicity ◽  
Xrd Patterns ◽  
Selection Of

A systematic study over different treatment conditions, including hydrothermal and acid-thermal, was successfully carried out to determine the most suitable conditions to enhance the textural properties and surface chemical composition of natural dolomite. The reconstruction of dolomite after various treatments enhanced the surface area by 4–5 times and diminished the pore diameter between 70% and 81% compared to the untreated parent dolomite. The Rietveld analysis of the X-ray diffraction (XRD) patterns revealed changes in the crystalline compositions after each treatment. When the treated dolomite was used as a catalyst to produce glycerol carbonate via a transesterification reaction of glycerol and dimethyl carbonate, the crystalline Ca(OH)2 concentration of the modified dolomite and the apparent glycerol carbonate formation rate (rgc) are well-correlated. The results suggest that an increase of the crystalline Ca(OH)2 concentration could be related with surface basicity at the weak and moderate strength sites that may lead to an increase in catalytic activity. The hydrothermal treated dolomite showed a selectivity of glycerol carbonate greater than 99% and rgc value 3.42 mmol/min·gcat, which was higher than that achieved on other samples. This study could aid to the proper selection of dolomite treatment for the desired crystalline composition, depending on the applications of this highly available mineral.

scholarly journals Polymorphism of tricalcium silicate in Portland cement: A fast visual identification of structure and superstructure

2003 ◽  
Vol 18 (1) ◽  
pp. 7-15 ◽  
Author(s):  
M. Courtial ◽  
M.-N. de Noirfontaine ◽  
F. Dunstetter ◽  
G. Gasecki ◽  
M. Signes-Frehel
Keyword(s):  
Portland Cement ◽  
Structural Model ◽  
Rietveld Analysis ◽  
Tricalcium Silicate ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Diffraction Patterns ◽  
Xrd Patterns ◽  
Industrial Compounds ◽  
Open Question

So-called alite is a solid solution of tricalcium silicate Ca3SiO5 with a few percent of impurities. It constitutes the major phase of anhydrous Portland cement. In industrial compounds, alite crystallizes into two monoclinic forms designated M1 and M3. The possibility of correlation between the crystallographic structure of the clinker and its reactivity is still an open question. The answer of such a question involves a proper quantitative analysis of the various phases—including the exact alite polymorph—of the industrial product. The rather similar structure of the two alites makes it difficult to distinguish them from their XRD patterns. This paper shows that five angular windows in the X-ray diffraction patterns can be used with synthetic alites as well as industrial compounds, to identify the nature of the actual polymorph (M1 or M3) present and the structural model to be used (with or without superstructure) in subsequent Rietveld analysis of the data.

scholarly journals Ternary Hydrotalcites in the Multicomponent Synthesis of 4H-Pyrans

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 70 ◽  
Author(s):  
Eliana Nope ◽  
Ángel G. Sathicq ◽  
José J. Martínez ◽  
Hugo A. Rojas ◽  
Rafael Luque ◽  
...  
Keyword(s):  
Divalent Cations ◽  
Textural Properties ◽  
Precipitation Method ◽  
Ni Catalyst ◽  
X Ray Diffraction ◽  
Multicomponent Synthesis ◽  
Solvent Free Conditions ◽  
Xrd Patterns ◽  
Co Precipitation ◽  
Double Hydroxides

Lamellar double hydroxides (LDH) with double divalent cations were synthesized by the co-precipitation method and studied in the multicomponent synthesis of 4H-pyrans. The solids obtained were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), N2 adsorption isotherms, and thermogravimetric analysis (TGA). The XRD patterns confirmed the formation of LDHs in which the incorporation of Ni2+ or Co2+ improves their crystalline and textural properties. The results of catalytic activity showed that the synthesis of 4H-pyrans is favored in solvent-free conditions with the LDH–Ni catalyst, avoiding calcination processes. In addition, it was found that hydrotalcite with double divalent cations can conduct this reaction through multicomponent synthesis or by the Michael addition reaction, which can be performed by different types of basicity that depend on the composition of another divalent cation in the brucite layer or a calcination process.

Structural and Raman spectroscopic studies of the two M0.50SbFe(PO4)3 (M = Mg, Ni) NASICON phases

2017 ◽  
Vol 32 (S1) ◽  
pp. S40-S51
Author(s):  
Abderrahim Aatiq ◽  
Asmaa Marchoud ◽  
Hajar Bellefqih ◽  
My Rachid Tigha
Keyword(s):  
Room Temperature ◽  
Structural Information ◽  
Rietveld Analysis ◽  
Spectroscopic Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Unit Cells ◽  
Xrd Patterns

Structures of the two M0.50SbFe(PO4)3 (M = Mg, Ni) phases, abbreviated as [Mg0.50] and [Ni0.50], were determined at room temperature from X-ray diffraction (XRD) powder data using the Rietveld analysis. Both compounds belong to the NASICON structural family. XRD patterns of [Mg0.50] and [Ni0.50] phases were easily indexed with a primitive hexagonal unit cell [P$\overline 3 $ space group, Z = 6] similar to that already obtained for La0.33Zr2(PO4)3. Obtained unit cells parameters are [a = 8.3443(1) Å, c = 22.3629(1) Å], and [a = 8.3384(1), c = 22.3456(1) Å], respectively, for [Mg0.50] and [Ni0.50] phosphates. In both samples, the [Sb(Fe)(PO4)3]− NASICON framework is preserved and a partially-ordered distribution of Sb5+ and Fe3+ ions is observed. Raman spectroscopic study was used to obtain further structural information about the nature of bonding in [Mg0.50] and [Ni0.50] phases.

scholarly journals Cheap Nano-Adsorbents Based on Zno/Mineral Nanocomposites for Removal of Chloroform from Water Solution

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
Farzad Salehi-Babarsad ◽  
Ehsan Derikvand ◽  
Majid Razaz ◽  
Ramin Yousefi ◽  
Abbas Shirmardi
Keyword(s):  
Kinetic Models ◽  
Water Solution ◽  
Textural Properties ◽  
X Ray Diffraction ◽  
Hazardous Chemical ◽  
Characteristic Adsorption ◽  
Isotherm And Kinetic Models ◽  
Heart Disorders ◽  
Ph Range ◽  
Xrd Patterns

Background: Chloroform, as a hazardous chemical, can contaminate water resources via the reaction of chlorine as an antiseptic chemical with humic acids resulted from agricultural activities. In humans, chloroform may cause dizziness, heart disorders, and disorders of the nervous system. Hence, its removal is of crucial importance. Objectives: The current study aimed to propose cheap and efficient adsorbents to remove chloroform from water. Methods: Four different nanomaterials (ZnO, ZnO/graphene oxide (ZnO/GO), ZnO/GO/Zeolite, and GO/Zeolite nanocomposites) were prepared and characterized with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) images. Textural properties of the nano- adsorbents were evaluated using Brunauer Emmet Teller (BET) and Barrett-Joyner-Halenda (BJH) techniques. Different isotherms and kinetic models were studied. The effect of pH on the removal efficiency of the nano-adsorbents was tested. Regenerability of the nano-adsorbents towards the removal of the chloroform was also evaluated. Results: XRD patterns and FESEM images of the nanocomposites confirmed lattice structures and nanoscale particle size of the prepared nanocomposites. According to the BET and BJH models, all samples had mesoporous structures. The BJH cumulative surface area of pores of ZnO, ZnO/GO, ZnO/GO/Zeolite, and GO/Zeolite nanocomposites were 8.5, 26.4, 17.2, and 20.8 m2/g, respectively. The best removal speed and efficiency were obtained according to the different isotherm and kinetic models for the removal of chloroform ZnO/GO nanocomposites. All adsorbents revealed characteristic adsorption in the pH range of 7 to 8. Conclusion: The ZnO/GO, a cheap and efficient nanocomposite, showed the best performance to remove chloroform from water samples due to its superior textural property. Hence, it can be used to remove chloroform from water for up to 5 cycles.

Synthesis, Characterization, and Electrochemical Performances of Substituted Layered Transition Metal Oxides. LiM1-yM'yO2. (M=Ni and Co. M'= B and AI)

1996 ◽  
Vol 453 ◽  
Author(s):  
G. A. Nazri ◽  
A. Rougier ◽  
K. F. Kia
Keyword(s):  
Transition Metal Oxides ◽  
Solubility Limit ◽  
Electrochemical Performances ◽  
X Ray Diffraction ◽  
X Ray ◽  
Long Cycle Life ◽  
Line Intensities ◽  
Treatment Conditions ◽  
Layered Transition Metal ◽  
Selection Of

AbstractThe synthesis, characterization and electrochemical performances of lithiated nickelate and cobaltate doped with Al and B are reported. The synthesis involves solid state reaction between lithium hydroxide, nickel or cobalt oxides and several sources of aluminum and boron. Careful selection of precursors and heat treatment conditions are required to prepare single phase impurity free samples. X-ray diffraction and Rietveld refinement analysis indicate that the layered structure is preserved upon considerable substitution of aluminum and boron. X-ray diffraction line intensities and positions remained in good agreement with the space group. The IR spectra of the samples indicate formation of compressed CoO6 and NiO6, and elongated LiO6 octahedra. The IR vibrational mode of the LiO6 remains in the 200–300 cm-1 and the vibrational modes of the MO6 expand over 400–650 cm-1. Results of long charge-discharge cycling of the samples as cathode materials in lithium cells showed long cycle life. The capacity of the electrodes upon substitution were reduced almost linearly as the concentration of substitution was increased. The solubility limit for the formation of solid solutions upon substitution of Al and B in LiNiO2 and LiCoO2 was found to be around 25%. Specific capacities of the samples were between 120 to 160 mAh/g depending on the amount of substitution.

Rietveld Analysis of Aurivillius-Type Structure Ceramics Synthesized from Precursors Prepared by Classical and HEBM Methods

2013 ◽  
Vol 203-204 ◽  
pp. 319-322
Author(s):  
Jolanta Dercz ◽  
Grzegorz Dercz ◽  
Krystian Prusik ◽  
Rafał Babilas
Keyword(s):  
Single Phase ◽  
Rietveld Method ◽  
Rietveld Analysis ◽  
High Energy ◽  
Energy Structure ◽  
X Ray Diffraction ◽  
Network Parameters ◽  
Porcelain Mortar ◽  
Xrd Patterns ◽  
Xrd Method

The aim of this study was to analyze the influence of the method of preparing the substrates in the form of simple oxides for the structure of the final Bi5Ti3FeO15ceramics. Milling of the substrates was carried out by two methods: the classical one by hand mixing in a porcelain mortar, and by high-energy. Structure studies were performed by the X-ray diffraction (XRD) method. XRD patterns were analyzed with the Rietveld method using the DBWS 9807a program. It was found out that the slightest deviation of the network parameters from the catalog data occurs for the sample obtained from simple oxides by free sintering (BTFs). Furthermore, it was also determined that the optimal high-energy time of the substrates is 5 hours. When compared to the ICDD catalog data, the resulting ceramics is a single phase one and has the lowest network parameters deviation among all samples which were subject to high-energy.

scholarly journals Glow discharge effect on temperature and time of treatment for the synthesis of Mo-doped manganite

DYNA ◽  
2019 ◽  
Vol 86 (209) ◽  
pp. 225-229
Author(s):  
Iván Supelano Gracía ◽  
William Arnulfo Aperador Pacheco ◽  
Carlos Parra Vargas ◽  
Armando Sarmiento Santos
Keyword(s):  
Glow Discharge ◽  
Room Temperature ◽  
Structural Transition ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Air Atmosphere ◽  
Inflection Points ◽  
Xrd Patterns ◽  
Time And Energy

We report the synthesis of CaMn0.9Mo0.1O3 manganite by glow discharge (GD) plasma treatment under Argon-Air atmosphere. The morphological, structural and magnetic properties were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and magnetization measures. The results from these measures reveal that the properties of GD synthesized manganite are similar to that exhibited by CaMn0.9Mo0.1O3 produced by conventional resistive furnace. The Rietveld analysis of XRD patterns performed at room temperature show that the samples crystallize in orthorhombic structure of Pnma (62) space group. The magnetization curves as a functionof temperature show two inflection points related to paramagnetic-antiferromagnetic and structural transition. The GD treatment produces a compound with similar properties, reducing the time and energy consumption in comparison with conventional synthesis route by using resistive furnace.

Rietveld Analysis of Ceramic Nuclear Waste Forms

1993 ◽  
Vol 333 ◽  
Author(s):  
T.J. White ◽  
H. Mitamura
Keyword(s):  
Rietveld Method ◽  
Amorphous Material ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Waste Forms ◽  
Simulated Waste ◽  
Diffraction Patterns ◽  
Nuclear Waste Forms ◽  
Selection Of

ABSTRACTPowder X-ray diffraction patterns were collected from three titanate waste forms - a calcine powder, a prototype ceramic without waste, and a ceramic containing 10 wt% JW-A simulated waste - and interpreted quantitatively using the Rietveld method. The calcine consisted of fluorite, pyrochlore, rutile, and amorphous material. The prototype waste form contained rutile, hollandite, zirconolite and perovskite. The phase constitution of the JW-A ceramic was freudenbergite, loveringite, hollandite, zirconolite, perovskite and baddeleyite. Procedures for the collection of X-ray data are described, as are assumptions inherent in the Rietveld approach. A selection of refined crystal data are presented.

scholarly journals DETERMINATION OF SILICA POLYMORPHS AND FELDSPARS IN INDUSTRIAL SAMPLES OF BENTONITE AND PERLITE

2017 ◽  
Vol 50 (4) ◽  
pp. 1878
Author(s):  
T. Kaza ◽  
M.G. Stamatakis
Keyword(s):  
Bulk Sample ◽  
X Ray Diffraction ◽  
Diffraction Patterns ◽  
Xrd Patterns ◽  
Industrial Samples ◽  
Reference Samples ◽  
Selection Of ◽  
Specific Amount

The aim of the present study is to apply a fast and reliable XRD method to identify the percentage of silica polymorphs and feldspars that industrial bentonite and perlite may contain, because these gangue minerals influence the quality of the final products. The current research was implemented by selecting of appropriate almost pure reference samples of bentonite and perlite in which specific amount of silica polymorphs and feldspars was added. The selection of all samples was based on the X-ray diffraction patterns. The synthetic mixtures produced were either with bentonite or perlite with a single added mineral or with two of them in percentages up to 10%. The minerals added to the reference samples were distinguishable in the XRD patterns in different percentages for each mineral added, but also in the two different reference samples. After evaluating of the XRD patterns of a series of samples, it was concluded that the lowest percentage of silica polymorphs and albite that was detected in the reference bentonite was 0.5% quartz, 1% cristobalite 10% opal CT, and 1% albite, whereas the percentages for the reference perlite was 1% quartz, 2% opal-CT, 1% cristobalite and 0.5% albite. This method can beapplied to any commercial bentonite and perlite bulk sample to define its purity concerning its silica polymorph and feldspar content.

SUPERCONDUCTING PROPERTIES OF Y1-xTbxBa2Cu3O7-δ AND Y1-xTbxSr2Cu2.7Mo0.3O7-δ

2010 ◽  
Vol 24 (04n05) ◽  
pp. 419-429 ◽  
Author(s):  
S. MIRSHAMSI ◽  
S. FALLAHI ◽  
M. AKHAVAN
Keyword(s):  
Secondary Phase ◽  
Rietveld Analysis ◽  
Creep Model ◽  
Structural Parameter ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Metallic Behavior ◽  
Thermally Activated ◽  
Diffraction Patterns ◽  
Xrd Patterns

We have investigated the effect of Tb substitution for Y in both YBa 2 Cu 3 O 7-δ and the more stabilized YSr 2 Cu 2.7 Mo 0.3 O 7-δ systems. Adding Mo has been shown to stabilize the Tb -doped systems. The samples of Y 1-x Tb x Ba 2 Cu 3 O 7-δ with x=0.0, 0.1, 0.15, 0.2, 0.3, 0.35, 0.4, 0.5, 0.55, and 0.6, and of Y 1-x Tb x Sr 2 Cu 2.7 Mo 0.3 O 7-δ with x=0.0, 0.2, 0.4, 0.6, and 0.8 have been prepared by the standard solid-state reaction technique. The superconducting transition occurs only with x=0–0.5 for the Ba -based samples, and with x=0–0.8 for the Sr -based samples. The structural parameter identification and phase determination of the samples have been carried out by the Rietveld analysis of the X-ray diffraction patterns, which indicates that Tb does not enter in the structure of the Ba -based 123 phase, while in the Sr -based 123 structure Tb enters in the structure and substitutes for Y . In the Y 1-x Tb x Ba 2 Cu 3 O 7-δ samples, a new secondary TbBaO 3 phase forms; and by increasing the amount of Tb , the secondary phase increases as the Y 123 phase decreases. But, for the Y 1-x Tb x Sr 2 Cu 2.7 Mo 0.3 O 7-δ samples, by increasing the amount of Tb doping, no impurity phase is detected in the XRD patterns. For both groups of samples, by increasing the amount of Tb , the normal resistivity increases, and the metallic behavior of the resistivity changes to semiconducting behavior. The magnetoresistance of Y 1-x Tb x Ba 2 Cu 3 O 7-δ was measured in different magnetic fields. The width of transition for the same values of magnetic field increases with the increase of Tb doping, indicating that with the increase of Tb , grains link weaker due to the increase in the amount of the secondary TbBaO 3 phase. The pinning energy has also been evaluated based on the thermally activated phase creep model.

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