Reaction Synthesis of Cr2AlC Ceramics Powders

2012 ◽  
Vol 624 ◽  
pp. 13-16
Author(s):  
Chun Long Guan ◽  
Zi Ping Zhang ◽  
Ying Chun Shan ◽  
Chun Hua Wang
Keyword(s):  
Effect Of Temperature ◽  
Molar Ratio ◽  
Reaction Synthesis ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Solid Reaction ◽  
X Ray ◽  
Temperature Range

Polycrystalline Cr2AlC was fabricated by a solid reaction synthesis of a mixture of Cr, Al and graphite powders in a flowing or the atmosphere in the temperature range of 700 to 1450 °C. The products for identification and analysis were characterized by X-ray diffraction (XRD). The effects of the composition of the initial elemental powders and temperature of purity and formation of Cr2AlC were examined. It is found that the co-existence of Cr7C3 with Cr2AlC is attributed to the surplus of carbon in the starting powders at 1350 °C, selecting the starting materials with a Cr: Al: C molar ratio of 2: (1.1-1.6): 1. For sample obtained from the starting elemental powders with the Cr: Al: C molar ratio of 2: 1.2: 0.94, no other phases but Cr2AlC were detected. In addition, the effect of temperature on the formation of Cr2AlC ceramic powders was carried out.

Raman Scattering and X-ray Diffraction Studies on Zinc(II)Bromide Solutions in Methanol and N,N-Dimethylformamide in the Temperature Range 77-333 K

1994 ◽  
Vol 49 (12) ◽  
pp. 1119-1130
Author(s):  
Toshiyuki Takamuku ◽  
Keisuke Nakamura ◽  
Mikito Ihara ◽  
Toshio Yamaguchi
Keyword(s):  
Raman Scattering ◽  
Methanol Solution ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Temperature Range ◽  
Methanol Solutions ◽  
Species Being ◽  
Bromide Solutions

Abstract The structure of zinc(II) bromo complexes in methanol and N,N-dimethylformamide (DMF) (molar ratio [solvent]/[ZnBr2] = 10, temperature range 77 -333 K) has been investigated by Raman scattering and X-ray diffraction. In the methanol solution symmetric Zn - Br vibrations (γ1) of the dibromo- and tribromozinc(II) complexes were observed at 209 and 184 cm-1, respectively. With decreasing temperature the intensity of the γ1 band decreased for the dibromo and increased for the tribromo complex. In addition, the γ1 band for the tetrabromo complex appeared in the supercooled and glassy methanol solutions. In the DMF solution only one band, assigned to both the dibromo-and tribromozinc(II) complexes, was observed. Its intensity did not change with temper­ature. The X-ray diffraction data revealed that the average number of Zn -Br interactions within the zinc (II) bromo complexes does not change with temperature while the number of nonbonding Br ··· Br interactions within the complexes increases from 1.5 at 298 K to 1.9 at 243 K for the methanol solution and from 1.3 at 298 K to 1.8 at 243 K for the DMF solution. These Raman and X-ray results have confirmed that in both methanol and DMF solutions at high temperatures the dibromo species is predominantly formed, whereas at low temperatures the tribromo complex is favored, the tetrabromo species being formed only in the supercooled and glassy methanol solutions. The temperature dependent equilibrium shifts of the zinc(II) bromo complexes in the methanol and DMF solutions are discussed together with previously reported results for the aqueous phase.

[Ca (2,2′-Bipyridine)3]2+-Intercalated Montmorillonite: An Application as Potentiometric Sensor

2012 ◽  
Vol 428 ◽  
pp. 7-13 ◽  
Author(s):  
S. Payungsak ◽  
Atchana Wongchaisuwat ◽  
Ladda Meesuk
Keyword(s):  
Interlayer Space ◽  
C:N Ratio ◽  
Potentiometric Sensor ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Solid Reaction ◽  
X Ray ◽  
Artificial Graphite ◽  
Higher Sensitivity

This article involves the use of [Ca (2,2′-bipyridine)3]2+-intercalated montmorillonite as a potentiometric sensor to measure anions in aqueous solution. The [Ca (2,2′-bipyridine)3]2+-intercalated montmorillonite was prepared by modification of an in situ solid-solid reaction, between natural Ca (II)-montmorillonite and 2,2′-bipyridine at a molar ratio 1:3. The formation of [Ca (2,2′-bipyridine)3]2+- in the interlayer space of montmorillonite was confirmed by powder X-ray diffraction (XRD) and the existence of 2,2′-bipyridine was confirmed by the C:N ratio of the product compared with that of the 2,2′-bipyridine molecule. The potentiometric sensor was constructed by mixing [Ca (2,2′-bipyridine)3]2+-intercalated montmorillonite with artificial graphite, polytetrafluoroethylene (PTFE) and carboxymethylcellulose (CMC) in an appropriate ratio. It was found that the sensor had higher sensitivity to S2- rather than other anions, graphs of log [S2-] vs voltage (mv) gave a slope 30.0 which was closed to theoretical value, 29.5. Activity of the [Ca (2,2′-bipyridine)3]2+ sensor was verified by using sensor made from Ca (II)-montmorillonite as a reference. Reproducibility and precision of the electrode were also determined.

Raman And Fluorescence Spectra Observed in Laser Microprobe Measurements of Several Compositions in the Ln-Ba-Cu-O System

1990 ◽  
Vol 48 (2) ◽  
pp. 278-279
Author(s):  
Edgar S. Etz ◽  
Thomas D. Schroeder ◽  
Winnie Wong-Ng
Keyword(s):  
Fluorescence Spectra ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Raman Microprobe ◽  
Methods Of Synthesis ◽  
Compositional Homogeneity ◽  
Processing Techniques

We are investigating by Raman microprobe measurements the superconducting and related phases in the LnBa2Cu3O7-x (for x=0 to 1) system where yttrium has been replaced by several of the lanthanide (Ln = Nd,Sm,Eu,Ho,Er) elements. The aim is to relate the observed optical spectra (Raman and fluorescence) to the compositional and structural properties of these solids as part of comprehensive materials characterization. The results are correlated with the methods of synthesis, the processing techniques of these materials, and their superconducting properties. Of relevance is the substitutional chemistry of these isostructural systems, the differences in the spectra, and their microanalytical usefulness for the detection of impurity phases, and the assessment of compositional homogeneity. The Raman spectra of most of these compounds are well understood from accounts in the literature.The materials examined here are mostly ceramic powders prepared by conventional solid state reaction techniques. The bulk samples are of nominally single-phase composition as determined by x-ray diffraction.

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.

Effect of Temperature on Fe3O4 Magnetic Nanoparticles Prepared by Coprecipitation Method

2014 ◽  
Vol 900 ◽  
pp. 172-176 ◽  
Author(s):  
Ji Mei Niu ◽  
Zhi Gang Zheng
Keyword(s):  
Magnetic Nanoparticles ◽  
Coprecipitation Method ◽  
Effect Of Temperature ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Magnetic Carriers ◽  
Average Grain Size ◽  
Or Gene ◽  
Block Temperature

The Fe3O4 magnetic nanoparticles obtained by the aqueous coprecipitation method are characterized systematically using scanning electron microscope, X-ray diffraction and vibrating sample magnetometer. These magnetic nanoparticles are spheric, dispersive, and have average grain size of 50 nm. The size and magnetic properties of Fe3O4 nanoparticles can be tuned by the reaction temperature. All samples exhibit high saturation magnetization (Ms=53.4 emu·g-1) and superparamagnetic behavior with a block temperature (TB) of 215K. These properties make such Fe3O4 magnetic nanoparticles worthy candidates for the magnetic carriers of targeted-drug or gene therapy in future.

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.

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.

A Sulfide Ion Sensor from Commercial Bentonite

2014 ◽  
Vol 894 ◽  
pp. 412-415
Author(s):  
Duangsamorn Morawong ◽  
Atchana Wongchaisuwat ◽  
Ladda Meesuk
Keyword(s):  
Interlayer Space ◽  
Intercalation Compound ◽  
X Ray Diffraction ◽  
Solid Reaction ◽  
X Ray ◽  
Sulfide Ion ◽  
Best Response ◽  
Percent Recovery ◽  
Synonymous Term ◽  
Nernstian Slope

Bentonite is a synonymous term of montmorillonite which is a clay mineral consisting of 2 : 1 aluminosilicate layered structure. In this work, a commercial bentonite was used to prepare an intercalation compound [Ca (2,2-bipyridine)3]2+in the interlayer space, by solid-solid reaction, which formation was confirmed by the expansion of the interlayer space of bentonite from 1.5 to 1.8 nm, by powder X-Ray Diffraction technique. The intercalation compound [Ca (2,2-bipyridine)3]2+-bentonite was then used as a sensor to assemble a potentiometric electrode. The electrode gave best response to sulfide ion in terms of Nernstian slope. Precision of measurement, reproducibility and percent recovery were also studied. The electrode could be used to measure sulfide ion in real water samples and gave satisfactory results.

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