Occurrence of Strontium–Iron Oxide SrFe12O19 in the Fe2O3–Na2O–SrSO4 System

1974 ◽  
Vol 52 (18) ◽  
pp. 3235-3246 ◽  
Author(s):  
R. J. Routil ◽  
D. Barham
Keyword(s):  
Exothermic Reaction ◽  
Hexagonal Lattice ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Mole Percent ◽  
X Ray ◽  
Second Stage ◽  
Third Stage ◽  
Final Yield ◽  
Three Stages

The formation of SrFe12O19 in the Fe2O3–Na2CO3–SrSO4 system was found to proceed through three stages, first an endothermic reaction between Fe2O3 and Na2CO3 to form Na2Fe2O4 and CO2, second an exothermic reaction of Na2Fe2O4 with SrSO4 to produce Na2SO4, Sr7Fe10O22, and SrFe12O19, third an exothermic reaction between Sr7Fe10O22 and Fe2O3 towards more SrFe12O19. The yield of SrFe12O19 depended on the molar ratio of the reactants and on temperature. Below 700 °C the formation did not proceed beyond the second stage. Samples prefired at 900–1200 °C contained SrFe12O19 in all cases when the original relative molar concentrations xFe2O3,yNa2CO3, and zSrSO4 satisfied the condition (x − y + z)/z > 5/7 or x/y > 5/7 ≥ x/z. Substitution of Na2CO3 in the reaction mixtures with equivalent amounts of NaOH or other precursors of Na2O did not affect the second and the third stage of the reaction and the final yield of SrFe12O19. On the ternary diagram of the Fe2O3–Na2O–SrSO4 system the SrFe12O19 region was represented by the area of a quadrilateral with the corner points located at the composition points 98-1-1, 1-1-98, 26-36-38, and 50-49-1 mole percent. The highest yields were obtained from the mixtures represented by the molar ratio 6Fe2O3:1 Na2O:1SrSO4. The hexagonal lattice parameters of SrFe12O19 were determined as a0 = 5.885 Å and c0 = 23.047 Å. X-Ray diffraction reflections of SrFe12O19 were indexed and reassignment of several indices in ASTM 7-276 for BaFe12O19 was suggested.

Extraction of Zirconium From Iraqi Bauxite Ore

2020 ◽  
Vol 38 (10A) ◽  
pp. 1421-1429
Author(s):  
Israa A. Aziz ◽  
Moayyed G. Jalhoom ◽  
Muhanad A. Kheriallah
Keyword(s):  
Nitric Acid ◽  
Contact Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid Ratio ◽  
Second Stage ◽  
Stirring Rate ◽  
Bauxite Ore ◽  
Three Stages ◽  
Hydrometallurgical Method

This research is devoted to the study of the extraction of zirconium from Iraqi Bauxite Ore by using hydrometallurgical method. The chemical analysis was done to the bauxite ore by using X-ray florescence, X-ray diffraction and atomic absorption spectroscopy. Zirconium Extraction was performed via three stages; the first stage is leaching of bauxite with sodium hydroxide for alumina leaching. The second stage is leaching of zirconium species from the remained powder produced from stage one after washing with deionized water and, nitric acid (HNO3 solutions). The results of the first stage has reflected the recovery of 42.27 % of Al2O3 which has been leached 100°C temperature, 7.5 molar of NaOH, liquid to solid ratio of 20/1, and stirring rate 450 rpm.  The highest leaching percent of zirconium (Zr%) from the red mud approached 98.48 % at 100°C temperature, 7 molar acid concentration, 120 min. contact time, solid to liquid  ratio (S/L) of 16/1, and stirring rate of 450 rpm. 99.47% recovery of zirconium was accomplished  from  nitric acid solutions by use of 3molar tri-n-butylephosphate (TBP)in kerosene at ,contact time for 6 min, and organic to aqueous phase (O/A) of 4/1.

Research on the Mechanism and Microstructure of an Al-Ti-C Parent Alloy Prepared Using the Villiaumite–Woodchip Method

2019 ◽  
Vol 960 ◽  
pp. 30-37
Author(s):  
Liu Yu ◽  
Yong Dong He ◽  
Yu Feng Du
Keyword(s):  
Synthesis Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Second Stage ◽  
Third Stage ◽  
Titanium Aluminum ◽  
Carbon Compounds ◽  
Parent Alloy ◽  
Cracking Products

X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, differential scanning calorimetry, and thermogravimetric analysis were used to study the microstructure and properties of an Al-Ti-C parent alloy prepared using the villiaumite–woodchip method. The synthesis process of the Al-Ti-C parent alloy prepared using the villiaumite–woodchip method and aluminum liquid had the following stages: The first stage was the formation of titanium aluminum by titanium being displaced from the reaction between aluminum and villiaumite. The second stage was the dehydration and carbonization reactions of the woodchips at high temperatures. The third stage involved titanium aluminum, carbon aluminum, and titanium carbon compounds constitute the Al-Ti-C parent alloy with a refined effect water and carbon dioxide, which were the cracking products of the woodchips, reacted with aluminum to produce alumina and hydrogen, which accumulated in the grain boundary in the form of slag-gas pockets.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

The Coherence of Mary Barton: Romance, Realism, and Utopia

2015 ◽  
Vol 5 (3) ◽  
pp. 185-200
Author(s):  
Robert Z. Birdwell
Keyword(s):  
Thomas Carlyle ◽  
The Novel ◽  
Second Stage ◽  
The Third ◽  
Third Stage ◽  
Three Stages ◽  
Mode Of Production

Critics have argued that Elizabeth Gaskell's first novel, Mary Barton (1848), is split by a conflict between the modes of realism and romance. But the conflict does not render the novel incoherent, because Gaskell surpasses both modes through a utopian narrative that breaks with the conflict of form and gives coherence to the whole novel. Gaskell not only depicts what Thomas Carlyle called the ‘Condition of England’ in her work but also develops, through three stages, the utopia that will redeem this condition. The first stage is romantic nostalgia, a backward glance at Eden from the countryside surrounding Manchester. The second stage occurs in Manchester, as Gaskell mixes romance with a realistic mode, tracing a utopian drive toward death. The third stage is the utopian break with romantic and realistic accounts of the Condition of England and with the inadequate preceding conceptions of utopia. This third stage transforms narrative modes and figures a new mode of production.

Effect of Hydrated Metal Salts on the Coordination Product of Cobalt(II) halide and PNP Type Ligand, 2,6-bis(di-tertbutylphosphinomethyl) pyridine

2018 ◽  
Author(s):  
Tasneem Siddiquee ◽  
Abdul Goni
Keyword(s):  
Metal Salts ◽  
Molar Ratio ◽  
Pincer Complexes ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Pincer Ligand ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Distorted Tetrahedral Geometry ◽  
Cobalt Center

Chemical treatment of CoX<sub>2</sub><b><sup>. </sup></b>6H<sub>2</sub>O (X = Cl, Br, I) with the potentially tridentate PNP pincer ligand 2,6-bis(di-<i>tert</i>-butylphosphinomethyl)pyridine in 1:1 molar ratio results in cobalt(II) halide-PNP pincer complexes. The effect of the hydrated metal source on molecular structure and geometry of the complexes was studied by single crystal X-ray diffraction analysis. The complexes are neutral and the cobalt center adopts a penta-coordinate system with potential atropisomerization. Within the unit cell there are two distinct molecules per asymmetric unit. One of the two phosphorus atoms in the PNP ligand was observed to be partially oxidized to phosphinoxide. Disorder in the structure reflects a mixture of square pyramidal and distorted tetrahedral geometry.

scholarly journals Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 346
Author(s):  
Sonam Goyal ◽  
Maizatul Shima Shaharun ◽  
Ganaga Suriya Jayabal ◽  
Chong Fai Kait ◽  
Bawadi Abdullah ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalyst Support ◽  
Oxidation Potential ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Optimum Parameters ◽  
Reduction Of Co2 ◽  
Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

A new model for packing of type-I collagen molecules in the native fibril

1981 ◽  
Vol 1 (10) ◽  
pp. 801-810 ◽  
Author(s):  
Karl A. Piez ◽  
Benes L. Trus
Keyword(s):  
Type I Collagen ◽  
Hexagonal Lattice ◽  
Three Dimensional ◽  
Equatorial Region ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Left Handed ◽  
Crystal Model ◽  
Collagen Molecules

A specific fibril model is presented consisting of bundles of five-stranded microfibrils, which are usually disordered (except axially) but under lateral compression become ordered. The features are as follows (where D = 234 residues or 67 nm): (1) D-staggered collagen molecules 4.5 D long in the helical microfibril have a left-handed supercoil with a pitch of 400–700 residues, but microfibrils need not have helical symmetry. (2) Straight-tilted 0.5-D overlap regions on a near-hexagonal lattice contribute the discrete x-ray diffraction reflections arising from lateral order, while the gap regions remain disordered. (3) The overlap regions are equivalent, but are crystallographically distinguished by systematic displacements from the near-hexagonal lattice. (4) The unit cell is the same as in a recently proposed three-dimensional crystal model, and calculated intensities in the equatorial region of the x-ray diffraction pattern agree with observed values.

Application of vermiculite and limestone to desulphurization and to the removal of dust during briquette combustion

2003 ◽  
Vol 67 (6) ◽  
pp. 1243-1251 ◽  
Author(s):  
A. Lu ◽  
D. Zhao ◽  
J. Li ◽  
C. Wang ◽  
S. Qin
Keyword(s):  
Electron Microscopy ◽  
Coal Combustion ◽  
Combustion Temperature ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Retention Ratio ◽  
X Ray ◽  
Major Factors ◽  
Chemical Reactant ◽  
Scanning Electron

AbstractSmall domestic cooking furnaces are widely used in China. These cooking furnaces release SO2 gas and dust into the atmosphere and cause serious air pollution. Experiments were conducted to investigate the effects of vermiculite, limestone or CaCO3, and combustion temperature and time on desulphurization and dust removal during briquette combustion in small domestic cooking furnaces. Additives used in the coal are vermiculite, CaCO3 and bentonite. Vermiculite is used for its expansion property to improve the contact between CaCO3 and SO2 and to convey O2 into the interior of briquette; CaCO3 is used as a chemical reactant to react with SO2 to form CaSO4; and bentonite is used to develop briquette strength. Expansion of vermiculite develops loose interior structures, such as pores or cracks, inside the briquette, and thus brings enough oxygen for combustion and sulphation reaction. Effective combustion of the original carbon reduces amounts of dust in the fly ash. X-ray diffraction, optical microscopy, and scanning electron microscopy with energy dispersive X-ray analysis show that S exists in the ash only as anhydrite CaSO4, a product of SO2 reacting with CaCO3 and O2. The formation of CaSO4 effectively reduces or eliminates SO2 emission from coal combustion. The major factors controlling S retention are vermiculite, CaCO3 and combustion temperature. The S retention ratio increases with increasing vermiculite amount at 950°C. The S retention ratio also increases with increasing Ca/S molar ratio, and the best Ca/S ratio is 2-3 for most combustion. With 12 g of the original coal, 1 to 2 g of vermiculite, a molar Ca/S ratio of 2.55 by adding CaCO3, and some bentonite, a S retention ratio >65% can be readily achieved. The highest S retention ratio of 97.9% is achieved at 950°C with addition of 2 g of vermiculite, a Ca/S ratio of 2.55 and bentonite.

Synthesis, Characterization and Thermal Behavior of  HYP2O7·3H2O Electrical Properties of  HYP2O7

2021 ◽  
Author(s):  
Rahma Rahzelli Zrelli ◽  
Fathia Chehimi-Moumen ◽  
Dalila Ben Hassen-Chehimi ◽  
Malika Trabelsi-Ayadi
Keyword(s):  
Infrared Spectroscopy ◽  
Electrical Properties ◽  
Complex Analysis ◽  
Optical Band Gap ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Soft Chemistry ◽  
Medium Temperature ◽  
X Ray ◽  
Three Stages

Abstract The synthesis of the diphosphate HYP2O7·3H2O was made via soft chemistry route from evaporation of aqueous solution at room temperature. The obtained compound, was characterized by means of X-ray diffraction (XRD) and infrared spectroscopy (IR). The results showed a high purity phase. IR spectrum of this diphosphate revealed usual signals related to P2O7 diphosphate group and water molecules. The thermal decomposition of the synthesized product by DTA / TG proceeded through four stages leading to the formation of the Y2P4O13 as a final product. On the other hand, its decomposition by CRTA took place in three stages leading to the formation of the anhydrous diphosphate HYP2O7 as a final product. X-ray powder diffraction and infrared spectroscopy were used to identify these materials. Furthermore the electrical properties of the HYP2O7 were investigated through impedance complex analysis. Modest conductivity has been observed in this material at relatively medium temperature range. Activation energy of 0.67 and 1.44 eV, was deduced from the corresponding Arrhenius plot.The optical band gap of the title compound is calculated and found to be 2.71 eV.

Dispersion of TiO2 Nanotubes in a Chitosan Matrix

MRS Advances ◽  
2018 ◽  
Vol 3 (63) ◽  
pp. 3805-3810
Author(s):  
B. Núñez Mendoza ◽  
S.R. Vasquez-García ◽  
N. Flores-Ramírez ◽  
J. L. Rico ◽  
L. Zamora Peredo ◽  
...  
Keyword(s):  
Electrochemical Anodization ◽  
Infrared Spectrometry ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Second Stage ◽  
Chitosan Matrix ◽  
Third Stage ◽  
Membrane Type ◽  
Titanium Foils

ABSTRACTThis work presents the synthesis and characterization of TiO2 nanotubes (NTT) with chitosan (CS). In a first stage, electrochemical anodization of titanium foils was used to generate NTT in a membrane-type arrangement. From these experiments, suitable experimental conditions were selected. In a second stage, the synthesized NTT were detached from the titanium foils by sonication. In the third stage, the detached NTT were dispersed in an acid solution containing CS in various concentrations. Finally, the nanotubes-chitosan (NTT/CS) samples were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infrared Spectrometry (FTIR). Our results showed that the NTT presented very regular tube morphology with -OH and Ti-O- functional groups on the surface. The interaction of NTT and chitosan was enhanced by increasing the time of contact during the synthesis of the titanium composites.

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