scholarly journals Synthesis of magnesium carbonate hydrate from natural talc

2020 ◽  
Vol 18 (1) ◽  
pp. 951-961
Author(s):  
Qiuju Chen ◽  
Tao Hui ◽  
Hongjuan Sun ◽  
Tongjiang Peng ◽  
Wenjin Ding
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Crystal Growth ◽  
Crystal Morphology ◽  
Magnesium Carbonate ◽  
Organic Additives ◽  
X Ray Diffraction ◽  
Morphological Transformation ◽  
X Ray ◽  
Carbonation Process

AbstractVarious morphologies of magnesium carbonate hydrate had been synthesized without using any organic additives by carefully adjusting the reaction temperature and time during the talc carbonation process. At lower temperatures, magnesium carbonate hydrate was prone to display needle-like morphology. With the further increase of the carbonation temperature, the sheet-like crystallites became the preferred morphology, and at higher aging temperatures, these crystallites tended to assemble into layer-like structures with diverse morphologies, such as rose-like particles and nest-like structure. The reaction time had no effect on the crystal morphology, but it affected the particle size and situation of the crystal growth. X-Ray diffraction results showed that these various morphologies were closely related to their crystal structure and compositions. The needle-like magnesium carbonate hydrate had a formula of MgCO3·3H2O, whereas with the morphological transformation from needle-like to sheet-like, rose-like, and nest-like structure, their corresponding compositions also changed from MgCO3·3H2O to 4MgCO3·Mg(OH)2·8H2O, 4MgCO3·Mg(OH)2·5H2O, and 4MgCO3·Mg(OH)2·4H2O.

Effect of Iron Substitution on Structure and Optical Properties of Nanocrystalline CaTiO3

2008 ◽  
Vol 3 ◽  
pp. 123-128 ◽  
Author(s):  
A. Bandyopadhyay ◽  
S. Mondal ◽  
M. Pal ◽  
Umapada Pal ◽  
M. Pal
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Iron Concentration ◽  
Rietveld Analysis ◽  
Exothermic Peak ◽  
Optical And Electrical Properties ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
X Ray ◽  
Soft Chemical Route

Nanocrystalline CaTiO3 powders doped with Fe2O3 have been prepared using a soft chemical route. Precipitation of CaTiO3 nanocrystals has been studied by monitoring the exothermic peak in their DSC spectra. The crystal growth temperature of the samples depends on the concentration of iron. Surface morphology, crystal structure, optical and electrical properties of the nanostructures are investigated. X-ray diffraction study shows that the as-prepared powders are amorphous in nature and CaTiO3 phase formation starts at around 500 0C. Rietveld analysis revealed that the particle size of iron substituted CaTiO3 is in nanometer range. Optical bandgap of the nanostructures varies from 4.3 to 3.7 eV for the variation of iron concentration from 0.05 to 0.2 mole %.

Structural and IR-spectroscopic characterization of magnesium acesulfamate

2016 ◽  
Vol 71 (1) ◽  
pp. 51-55 ◽  
Author(s):  
Oscar E. Piro ◽  
Gustavo A. Echeverría ◽  
Beatriz S. Parajón-Costa ◽  
Enrique J. Baran
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Elemental Analysis ◽  
Spectroscopic Characterization ◽  
Magnesium Carbonate ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Ir Spectroscopic

AbstractMagnesium acesulfamate, Mg(C4H4NO4S)2·6H2O, was prepared by the reaction of acesulfamic acid and magnesium carbonate in aqueous solution, and characterized by elemental analysis. Its crystal structure was determined by single crystal X-ray diffraction methods. The substance crystallizes in the triclinic space group P1̅ with one molecule per unit cell. The FTIR spectrum of the compound was also recorded and is briefly discussed. Some comparisons with other simple acesulfamate and saccharinate salts are also made.

Synthesis and sintering of SiC under high pressure and high temperature

1999 ◽  
Vol 14 (3) ◽  
pp. 906-911 ◽  
Author(s):  
S. K. Bhaumik ◽  
C. Divakar ◽  
S. Usha Devi ◽  
A. K. Singh
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
High Pressure ◽  
Silicon Powder ◽  
Synthesis Temperature ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microscopic Studies ◽  
Simultaneous Synthesis

Starting from elemental powders, simultaneous synthesis and compaction of SiC were conducted at 3 GPa pressure and temperatures in the range 2100–2900 K. The sintered compacts were characterized by x-ray diffraction, microhardness measurements, and microscopic studies. The efficiency of formation of SiC was dependent on the particle size of the silicon powder, crystallinity of the reactant carbon, molar ratio of silicon and carbon, and synthesis temperature and time. Carbon in excess of the stoichiometric amount was required to obtain compacts free from residual silicon. The SiC samples, with a Si: C molar ratio 1: 1.05, prepared at 2100 K for 300 s had a density and hardness of 3.21 g/cm3 (98.8% of theoretical density) and 22 GPa, respectively. The crystal structure of the SiC depended on the synthesis temperature. Pure β–SiC in the temperature range 2100–2500 K, and a mixture of α– and β–SiC above 2500 K were obtained. The β–SiC was highly crystalline and nearly defect-free.

William Barlow’s early publications in the ‘Zeitschrift für Krystallographie und Mineralogie’ and their influence on crystal structure research

2019 ◽  
Vol 234 (11-12) ◽  
pp. 769-785 ◽  
Author(s):  
Peter Paufler
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Crystal Morphology ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Starting Point ◽  
Diffraction Patterns ◽  
Structure Research

AbstractThe English crystallographer William Barlow is famous for two achievements, both published in German, in Zeitschrift für Krystallographie und Mineralogie between 1894 and 1901. They concern the derivation of all possible symmetrical arrangements of points in space and the idea to represent crystal structures by replacing points by spheres. His results had an impact upon crystal structure modelling and describing crystal morphology. Utilizing self-made models, he found the 230 space group types of symmetry obtained earlier by both E. S. Fedorow and A. Schoenflies in a different manner. The structures he proposed before the discovery of X-ray diffraction served in some cases as starting point for the interpretation of diffraction patterns thereafter.

Crystal growth, crystal structure, optical, electro-optic and electrostrictive properties of the orthorhombic tartrato-antimonate(III) nitrate KZn[Sb2{(+)-C4H2O6}2]NO3 · 5 H2O (“KZnSbTN”)

1994 ◽  
Vol 209 (1) ◽  
Author(s):  
L. Bohatý ◽  
R. Fröhlich
Keyword(s):  
Crystal Structure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Single Crystals ◽  
Diffraction Data ◽  
Title Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electro Optic ◽  
Electrostrictive Properties

AbstractKZnSbTN is an example from the large acentric double salt-like family of tartrato-antimonates. Its crystal structure was determined from single-crystal X-ray diffraction data (orthorhombic,Single crystals of the title compound of up to 4×4×6 cm

scholarly journals Mechanical alloying of iron-coated NbC and Si in stirred media mill

2019 ◽  
Vol 55 (2) ◽  
pp. 209-216 ◽  
Author(s):  
A. Al-Azzawi ◽  
F. Kristály ◽  
Á. Rácz ◽  
P. Baumli ◽  
K. Bohács ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Mechanical Alloying ◽  
Structural Changes ◽  
Nanocrystalline Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Batch Type ◽  
Stress Energy ◽  
Stirred Media Mill

In the current research, the effect of mechanical alloying (MA) of iron-coated NbC and Si on the material?s fineness and crystal structure was investigated. The MA experiments were carried out in a batch-type laboratory scale stirred media mill for various residence times up to 240 min in isopropanol. During MA, milling energy was measured, and stress energy (SE) was calculated. Morphology and material structural changes, during the mechanical alloying process, were determined by means of scanning electron microscopy (SEM) and powder X-ray diffraction (XRD), respectively. The particle size distribution of the product was measured by a Horiba 950 LA laser particle size analyser. Evolution of phases during highenergy milling of NbC, Al-Fe-carbide, Fe, and Si was studied as a function of specific milling energy. Transformations in the crystal structure were revealed, namely the generation of cementite and Nb-Si-carbide, which was proved by XRD results and thermodynamic calculations. As result of the experiments, optimum MA conditions were determined. The application of the mechanical alloying method gives the opportunity to produce nanocrystalline phase from the initial ironcoated NbC and Si powder

scholarly journals Influence of the Shape of Copper Powder Particles on the Crystal Structure and Some Decisive Characteristics of the Metal Powders

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 56 ◽  
Author(s):  
Ljiljana Avramović ◽  
Vesna M. Maksimović ◽  
Zvezdana Baščarević ◽  
Nenad Ignjatović ◽  
Mile Bugarin ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Structural Characteristics ◽  
Metal Powders ◽  
X Ray Diffraction ◽  
Applied Current ◽  
X Ray ◽  
Powder Particles ◽  
Micro Structures ◽  
Spherical Grains

Three different forms of Cu powder particles obtained by either galvanostatic electrolysis or a non-electrolytic method were analyzed by a scanning electron microscope (SEM), X-ray diffraction (XRD) and particle size distribution (PSD). Electrolytic procedures were performed under different hydrogen evolution conditions, leading to the formation of either 3D branched dendrites or disperse cauliflower-like particles. The third type of particles were compact agglomerates of the Cu grains, whose structural characteristics indicated that they were formed by a non-electrolytic method. Unlike the sharp tips that characterize the usual form of Cu dendrites, the ends of both the trunk and branches were globules in the formed dendrites, indicating that a novel type of Cu dendrites was formed in this investigation. Although the macro structures of the particles were extremely varied, they had very similar micro structures because they were constructed by spherical grains. The Cu crystallites were randomly oriented in the dendrites and compact agglomerates of the Cu grains, while the disperse cauliflower-like particles showed (220) and (311) preferred orientation. This indicates that the applied current density affects not only the morphology of the particles, but also their crystal structure. The best performance, defined by the largest specific surface area and the smallest particle size, was by the galvanostatically produced powder consisting of disperse cauliflower-like particles.

Correlation of Crystal Morphology and Structure Using a Modified X-Ray Film Technique

1987 ◽  
Vol 41 (1) ◽  
pp. 106-110 ◽  
Author(s):  
Ronald L. Musselman ◽  
Annegret A. G. Schneider
Keyword(s):  
Crystal Structure ◽  
Crystal Morphology ◽  
Crystalline Morphology ◽  
X Ray Diffraction ◽  
X Ray ◽  
Polarized Spectroscopy ◽  
Morphology And Structure ◽  
Diffraction Photograph ◽  
Convenient Technique

A convenient technique for the determination of the orientation of a solid-state molecule with respect to its crystalline morphology is presented. The process is especially suitable for spectroscopists wishing to orient crystals in preparation for polarized spectroscopy. Correlation of reciprocal axes with the crystal faces is accomplished by pinholes through a 0-level Weissenberg x-ray diffraction photograph, which allows assignment of spindle angles to lateral positions on the film. The correlation is extended to ORTEP drawings where a scaled-down crystal morphology is included in a standard crystal structure plot, enabling a clear picture of molecular orientations within a crystal. Viewing normal to actual crystal faces allows determination of molecular projections onto desired faces for alignment prior to polarized spectroscopy.

scholarly journals A new hydrate of magnesium carbonate, MgCO3·6H2O

2020 ◽  
Vol 76 (3) ◽  
pp. 244-249
Author(s):  
Christine Rincke ◽  
Horst Schmidt ◽  
Wolfgang Voigt
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Diffraction Pattern ◽  
Raman Spectra ◽  
Room Temperature ◽  
Magnesium Carbonate ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Phase

During investigations of the formation of hydrated magnesium carbonates, a sample of the previously unknown magnesium carbonate hexahydrate (MgCO3·6H2O) was synthesized in an aqueous solution at 273.15 K. The crystal structure consists of edge-linked isolated pairs of Mg(CO3)(H2O)4 octahedra and noncoordinating water molecules, and exhibits similarities to NiCO3·5.5H2O (hellyerite). The recorded X-ray diffraction pattern and the Raman spectra confirmed the formation of a new phase and its transformation to magnesium carbonate trihydrate (MgCO3·3H2O) at room temperature.

Electron Mtcroscope Study of the Structure of Natural Pyrolusite (Pseudo-Psilomelane)

1973 ◽  
Vol 31 ◽  
pp. 194-195
Author(s):  
K. P. Staudhammer ◽  
L. E. Murr
Keyword(s):  
Crystal Structure ◽  
Crystal Growth ◽  
New Mexico ◽  
Manganese Oxide ◽  
Black Hair ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Crystal

A manganese-bearing mineral characterized by a black hair-like surface crystal growth, and somewhat unique to the Socorro County, New Mexico area, has been referred to as psilomelane (pseudo-pyrolusite). Psilomelane, however, is a hydrated barium manganese oxide, generally A 3 X6Mn8016 (A= B2+, Mn3+, Al3+, Fe3+, S14+, etc. and X=O, OH). Natural psllomelane 1s a smooth, black, uniform or botryoidal mineral possessing an or- thorhombic crystal structure.Large specimens of the hair-like c·rystalline mineral (Fig. 1 (a) were analyzed by X-ray diffraction utilizing Debye-Scherrer nd diffractometer techniques and found to be tetragonal (a=4.42A, c = 2.87A).

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