Effect of thermal treatment on lanthanide montmorillonites: dehydration

Clay Minerals ◽  
1980 ◽  
Vol 15 (4) ◽  
pp. 421-428 ◽  
Author(s):  
T. Mozas ◽  
S. Bruque ◽  
A. Rodriguez
Keyword(s):  
Thermal Analysis ◽  
Thermal Treatment ◽  
Interlayer Space ◽  
Lanthanide Ions ◽  
Water Molecules ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
Interlayer Water ◽  
X Ray ◽  
Water Layers

AbstractHydration/dehydration behaviour and the effect of various thermal treatments on montmorillonites saturated with lanthanide ions have been investigated by X-ray diffraction, thermal analysis (DTA, TG, DTG), IR spectroscopy and sorption-desorption of water vapour techniques. Heating at 150°C under 10−5 torr did not eliminate all the interlayer water of the montmorillonite, neither did it affect the CEC. Heating above 160°C caused a reduction in CEC. At 25°C La-montmorillonite takes up a maximum of three water layers in the interlayer space, the water molecules adopting a nonacoordinated distribution around the La3+ cation.

scholarly journals Structural changes of Cr-beidellite treated up to 1350 °C in oxygen or nitrogen atmospheres

Cerâmica ◽  
2018 ◽  
Vol 64 (369) ◽  
pp. 64-68
Author(s):  
H. S. Santos ◽  
A. M. Cesio ◽  
M. Gauna ◽  
V. F. Justo ◽  
C. Volzone
Keyword(s):  
Thermal Analysis ◽  
High Temperature ◽  
Thermal Treatment ◽  
Structural Changes ◽  
Pillared Clay ◽  
Nitrogen Atmosphere ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineralogical Phases

Abstract Beidellite clay mineral after intercalation of OH-Cr(III) species were thermally analyzed up to 1350 °C in oxygen and nitrogen atmospheres. OH-Cr-beidellite can be used as a pillared clay precursor for catalysis or as adsorbent applications. However, in this paper beidellite enriched in chromium were analyzed at different thermal treatments up to high temperature for evaluating structural changes for possible future ceramic applications. The structural changes were followed by thermal analysis and X-ray diffraction. The thermal treatment of OH-Cr-beidellite in oxygen and nitrogen atmospheres developed different mineralogical phases up to 1050 °C, but at higher temperatures, the same phases were developed in both atmosphere treatments. Eskolaite phase (Cr2O3) appeared in the sample after heating at 400 °C in oxygen atmosphere, whereas grimaldite (CrO-OH) in nitrogen atmosphere, maintaining the starting phases. At 1000 °C the raw clay minerals disappeared, as it is knew. At 1050 °C in nitrogen atmosphere, grimaldite was absent and eskolaite appeared. At 1350 °C in the samples calcined in both atmospheres, quartz, cristobalite and mullite as the main phases and in lower contents aluminum oxide and aluminum-chromium oxide [(Al,Cr)2O3] were present.

Room temperature conversion of X0.3V2O5· nH2O phase into X2V6O16· nH2O phase Influence of the nature of the cation X+

2004 ◽  
Vol 848 ◽  
Author(s):  
Olivier Durupthy ◽  
Saïd Es-salhi ◽  
Nathalie Steunou ◽  
Thibaud Coradin ◽  
Jacques Livage
Keyword(s):  
Vanadium Oxide ◽  
Room Temperature ◽  
Interlayer Space ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxide Phases ◽  
New Phase ◽  
Supernatant Solution ◽  
Scanning Electron

ABSTRACTVarious cations (Li+, Na+, K+, NH4+, Cs+, Mg2+, Ca2+, Ba2+) were introduced during the formation of a V2O5. nH2O gel. Cation intercalated Xy V2O5. nH2O (y = 0.3 for X = Li+, Na+, K+, NH4+ or y = 0.15 for Mg2+, Ca2+, Ba2+) were first obtained at room temperature but some of them evolve upon ageing into a new phase: XV3O8. nH2O for X = Na+, K+, NH4+ and Cs+ or XV6O16. nH2O for X = Mg2+, Ca2+, Ba2+. All the vanadium oxide phases were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy (IR); the supernatant solutions were analysed by 51V NMR spectroscopy. These vanadium oxide phases exhibit a layered structure with cations and water molecules intercalated within the interlayer space. The formation of the different phases depends mainly on the pH of the supernatant solution and on the nature of the cation.

Thermal conversion of gels to YBa2Cu3Ox, Bi2Sr2CaCu2Ox, and (Bi, Pb)2Sr2Ca2Cu3Ox and their decarbonization by low-temperature treatment with nitric acid

1996 ◽  
Vol 11 (1) ◽  
pp. 1-4 ◽  
Author(s):  
A. Deptula ◽  
T. Olczak ◽  
W. Lada ◽  
K. C. Goretta ◽  
A. Di Bartolomeo ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Nitric Acid ◽  
Thermal Treatment ◽  
Thermal Conversion ◽  
Temperature Treatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Temperature Treatment ◽  
Intermediate Phases ◽  
Superconducting Compounds

Thermal conversion of acetate-derived gels to YBa2Cu3Ox (Y–123), Bi2Sr2CaCu2Ox (Bi–2212), and (Bi, Pb)2Sr2Ca2Cu3Ox (Bi-2223) has been studied by thermal analysis, x-ray diffraction, and infrared spectroscopy. Carbonates formed above 200 °C during thermal treatment of all gels. Decomposition of the carbonates proved to be more difficult for Y-123 than for Bi-2212 or Bi-2223. However, all of the gels that were heated contained significant amounts of carbon after calcination. Complete decarbonization of materials was attained by treating the intermediate phases (e.g., those formed after calcination at 600 °C) with nitric acid and then subjecting them to a final thermal treatment. Removal of carbonates from the intermediate phases strongly accelerated formation of the superconducting compounds.

Study on Character of Ilmenite Modified by Thermal Treatment

2011 ◽  
Vol 284-286 ◽  
pp. 2090-2093 ◽  
Author(s):  
Xue Liang Xiong ◽  
Zhi Yang ◽  
Hong Yong Ouyang
Keyword(s):  
Thermal Analysis ◽  
Solid Solution ◽  
Differential Thermal Analysis ◽  
Thermal Treatment ◽  
Oxidation Temperature ◽  
X Ray Diffraction ◽  
Thermo Gravimetric ◽  
X Ray

The character of ilmenite was modified by pretreatment, the effect of pre-oxidation temperature and time on structure of ilmenite were investigated by X-ray diffraction(XRD) and Thermo-gravimetric/differential thermal analysis. The results indicated that new microcrystal rutile and FeTiO3·Fe2O3 solid solution were appeared on the surface of mineral below 800°C, but evident rutile crystals and pseudobrookite Fe2O3·TiO2 were appeared above 850°C with the structure of ilmenite disrupting simultaneously. The preoxidation time increased from 15min to 60min, evident microcrystal rutile and FeTiO3·Fe2O3 solid solution were appeared by degrees without structure of ilmenite breaking.

scholarly journals Cu(II) and Cd(II) coordination polymers derived from pyrazine-2,3-dicarboxylato and 1-vinylimidazole ligands: Synthesis, characterization and hydrogen storage capacities

2019 ◽  
Vol 38 (1) ◽  
pp. 19 ◽  
Author(s):  
Semih Gorduk ◽  
Hakan Yilmaz ◽  
Omer Andac
Keyword(s):  
Thermal Analysis ◽  
Magnetic Susceptibility ◽  
Coordination Polymer ◽  
Hydrogen Storage ◽  
Coordination Polymers ◽  
Crystalline Form ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Areas

In this study, two new coordination polymers of Cu(II) and Cd(II) ions with pyrazine-2,3-dicarboxylic acid and 1-vinylimidazole were synthesized. The structures of these coordination polymers were characterized with elemental analysis, infrared spectroscopy, thermal analysis, powder X-ray diffraction, and magnetic susceptibility techniques. According to the results of the thermal analysis, the coordination polymers that contained water molecules decomposed below 100 °C, and the final products for both coordination polymers were the related metal oxides in an oxygen atmosphere. Powder X-ray diffraction analysis revealed that the coordination polymers were in the crystalline form. The hydrogen storage capacities and surface areas of the coordination polymers were also determined. The highest hydrogen storage capacities were measured as 296 ml/g for the Cu(II) coordination polymer and 330 ml/g for the Cd(II) coordination polymer at approximately 75 bar and 75 K.

scholarly journals Thermal Annealing and Phase Transformation of Serpentine-Like Garnierite

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 188
Author(s):  
Arun Kumar ◽  
Michele Cassetta ◽  
Marco Giarola ◽  
Marco Zanatta ◽  
Monique Le Guen ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Raman Spectroscopy ◽  
Phase Transformation ◽  
Differential Thermal Analysis ◽  
Thermal Treatment ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Thermally Induced ◽  
X Ray ◽  
Micro Raman Spectroscopy

This study is focused on the vibrational and microstructural aspects of the thermally induced transformation of serpentine-like garnierite into quartz, forsterite, and enstatite occurring at about 620 °C. Powder specimens of garnierite were annealed in static air between room temperature and 1000 °C. The kinetic of the transformation was investigated by means of thermogravimetric and differential thermal analysis, and the final product was extensively characterized via micro-Raman spectroscopy and X-ray diffraction. Our study shows that serpentine-like garnierite consists of a mixture of different mineral species. Furthermore, these garnierites and their composition can provide details based on the mineralogy and the crystalline phases resulting from the thermal treatment.

Preparation of drug-montmorillonite UV-radiation protection compounds by gas-solid adsorption

Clay Minerals ◽  
2001 ◽  
Vol 36 (4) ◽  
pp. 541-546 ◽  
Author(s):  
C. del Hoyo ◽  
M. A. Vicente ◽  
V. Rives
Keyword(s):  
High Temperature ◽  
Ultraviolet Radiation ◽  
Interlayer Space ◽  
External Surface ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Clay Surface ◽  
Intercalation Complexes ◽  
Pure Drug

AbstractEthyl cinnamate/montmorillonite intercalation complexes were obtained by gaseous adsorption of the drug on the clay surface. They were characterized by powder X-ray diffraction, differential thermal and thermogravimetric analyses and by visible-UV and IR spectroscopies. It was found that after 1 day of adsorption, most of the drug enters the interlayer space of the clay by substitution of water molecules, and is removed only after heating at high temperature. In addition, a portion is physisorbed on the external surface of the crystallites, being removed easily below 100°C. The interlayer complex improves the protecting ability of the pure clay or the pure drug against ultraviolet radiation, specially in the so-called ‘C’ range (290–190 nm).

Solid State Reaction Study Of The System Co-Li2CO3

1996 ◽  
Vol 51 (7) ◽  
pp. 813-820
Author(s):  
A. Marini ◽  
V. Berbenni ◽  
V. Massarotti ◽  
D. Capsoni ◽  
G. Bruni
Keyword(s):  
Solid State ◽  
Thermal Treatment ◽  
Solid State Reaction ◽  
Room Temperature ◽  
Reaction Model ◽  
Lithium Content ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reactive Processes

Abstract A detailed analysis of the reactive processes taking place in Co-Li2CO3 was performed by use of thermogravimetry and X-ray diffraction. A reaction model is proposed which accounts for the nature, stoichiometry, and amount of the phases present, at room temperature, in samples subjected to different thermal treatments. In particular it is shown that the thermal treatment influences substantially the final lithium content and the relative amount of the Li-containing phases. The results obtained for powdered samples are compared with those obtained in a previous work for plaques.

scholarly journals Experimental study of swelling in unsaturated compacted clays

Clay Minerals ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 469-479 ◽  
Author(s):  
N. Saiyouri ◽  
D. Tessier ◽  
P. Y. Hicher
Keyword(s):  
Particle Size ◽  
Water Molecules ◽  
Suction Pressure ◽  
X Ray Diffraction ◽  
Electronic Microscopy ◽  
Swelling Properties ◽  
X Ray ◽  
Water Layers ◽  
Compacted Clays ◽  
Clay Layers

AbstractThis paper describes the swelling properties of two highly compacted clays, natural, untreated Wyoming montmorillonite (MX80) and Fourges smectite (FoCa7), saturated with Na and Ca, respectively.The initially compacted samples were hydrated by subjecting them to different suction pressures in a range between 100 MPa and 1 kPa. For each equilibrium state, the volume change (swelling) and water content (hydration) were measured. The samples were then studied by X-ray diffraction using a transmission device to determine interlayer distance and particle size, in order to clarify both the swelling and hydration mechanisms. The distances between clay layers ranged between 10 and 21.6 Å , i.e. corresponding to between 0 and 4 water layers. Upon hydration, the particle size decreased from 350 and 100 clay layers per particle to 10 layers per particle when the suction pressure decreased from 100 MPa to 1 kPa for MX80 and FoCa7, respectively. The first swelling stage is described as being an insertion of water molecules between the layers. Then a division of the initial particles into particles of smaller size with increasingly large inter-particle distances was observed. Observations by transmission electronic microscopy confirmed these results.

scholarly journals The Structure and Properties of Fe(II) 1,10-Phenanthroline-Thiobarbiturate

2020 ◽  
pp. 479-488
Author(s):  
Nicolay N. Golovnev ◽  
Maxim S. Molokeev ◽  
Irina V. Sterkhova ◽  
Timur Yu. Ivanenko
Keyword(s):  
Thermal Analysis ◽  
Thiobarbituric Acid ◽  
Mononuclear Complex ◽  
Octahedral Complex ◽  
Water Molecules ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
Bipy Molecule

The structure of the mononuclear complex [Fe(Bipy)(H2O)2(Htba)2]∙6H2O (I), where Bipy – 2,2’-dipyridine, H2tba – 2-thiobarbituric acid (C4H4N2O2S), was determined by single crystal X-ray diffraction technique (cif-file CCDC No. 1831367). Crystals I are rhombic: a = 17.4697 (7), b = 11.7738 (4), c = 13.4314 (5) Å, V = 2762.6(2) Å3, space group Pnma, Z = 4. Two nitrogen atoms of the Bipy molecule and two water molecules are located in the equatorial plane of the octahedral complex, and two S-coordinated Htba− ions the axial positions are occupied. The structure is stabilized by N−H∙∙∙O, O−H∙∙∙O, С−H∙∙∙O, C−H∙∙∙S intermolecular hydrogen bonds and π–π interaction between Bipy and Htba−. The compound is characterized by the methods of powder X-ray diffraction, thermal analysis, and IR spectroscopy

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