Physicochemical Properties of New Dicationic Ether-Functionalized Low Melting Point Ammonium Salts

2010 ◽  
Vol 63 (7) ◽  
pp. 1122 ◽  
Author(s):  
Minna Kärnä ◽  
Manu Lahtinen ◽  
Pirkko-Leena Hakkarainen ◽  
Jussi Valkonen
Keyword(s):  
Physicochemical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Side Chain ◽  
Residual Water ◽  
X Ray Diffraction ◽  
Thermal Stabilities ◽  
X Ray ◽  
Heat Transfer Fluids ◽  
High Temperature Synthesis

Eleven new and one previously known but insufficiently characterized dicationic quaternary ammonium (QA) salts were synthesized and characterized. They contain an ethoxy ethyl group either in a side chain and/or as spacer of the diammonium cation and have bromide, hexafluorophosphate (PF6–), bis(trifluoromethanesulfonyl)imide (TFSI), or trifluoromethanesulfonate (TFMS) as an anion. 1H and 13C techniques, mass spectrometry, and elemental analysis together with X-ray diffraction and thermoanalytical methods were used for their characterization both in the liquid and solid state. In addition, residual water content and viscosity measurements were made for the two room temperature ionic liquids (RTILs). Capillary electrophoresis was used to measure the conductivity of the RTILs. Crystal structures of four compounds were determined by X-ray single crystal diffraction, and powder diffraction was used to study the crystallinity of the solid salts and to compare the structural similarities between the single crystals and the microcrystalline bulk form. Two of the TFSI salts were liquids below room temperature, having liquid ranges of ~380 and 350°C, respectively, and seven out of 12 salts melted below 100°C. In addition, both the TFSI and PF6 salts exhibited high thermal stabilities decomposing at about, or above 300°C. Both RTILs presented moderate viscosities at elevated temperatures. The determined physicochemical properties of the reported ILs suggest their applicability for various applications such as heat transfer fluids, high temperature synthesis, and lubricants.

Synthesis and Luminescence Properties of Chalcopyrite-Type CuAlS2

2006 ◽  
Vol 301 ◽  
pp. 177-180 ◽  
Author(s):  
Yuichiro Kuroki ◽  
Tomoichiro Okamoto ◽  
Masasuke Takata
Keyword(s):  
Diffraction Analysis ◽  
Room Temperature ◽  
Single Phase ◽  
Elevated Temperatures ◽  
Emission Peak ◽  
Maximum Intensity ◽  
X Ray Diffraction ◽  
Ultraviolet Emission ◽  
X Ray ◽  
Copper Aluminum

Copper aluminum disulfide (CuAlS2) powders were synthesized in an evacuated ampoule at elevated temperatures. X-ray diffraction analysis revealed that the powders heated at temperatures higher than 800oC were single-phase CuAlS2. In the cathodoluminescence (CL) spectra measured at room temperature, the powders heated at temperatures higher than 600oC exhibited a visible emission peak at approximately 1.8 eV and a distinct ultraviolet emission peak at 3.45 eV. The powder heated at 700oC showed the maximum intensity of ultraviolet emission which is considered to be associated with excitons.

Effect of Nd on Microstructures and Properties of AZ31 Wrought Mg Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 301-304
Author(s):  
Wei Qiu ◽  
En Hou Han ◽  
Lu Liu
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Mg Alloys ◽  
The Other ◽  
Mg Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructures And Mechanical Properties ◽  
Re Elements

Addition of RE elements to Al-containing Mg alloys can improve properties of Mg alloys at elevated temperatures. In the present investigation, hot-extruded AZ31+x%Nd. (x=0.1,0.3,0.6and1.0 wt%) wrought Mg alloy were prepared .The effects of Nd on microstructures and mechanical properties at room temperature of new alloy were investigated. The investigation found that Nd can bring about two kind of precipitation phases . One is AlNd phase, the other is AlNdMn phase, which were identified as Al11Nd3 and Al8NdMn4 by X-ray diffraction and TEM.

Microstructure and texture of Ti-6Al-4V alloy deformed by rotary forging at elevated temperatures

2020 ◽  
Vol 111 (10) ◽  
pp. 807-813
Author(s):  
Shan Jiang
Keyword(s):  
Grain Refinement ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Electron Back Scatter Diffraction ◽  
Dislocation Slip ◽  
Basal Texture ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rotary Forging ◽  
Main Deformation

Abstract Ti-6Al-4V alloy cylinder samples were subjected to rotary forging at temperatures ranging from room temperature to 1 473 K. The microstructure and texture were examined by means of electron back-scatter diffraction and X-ray diffraction. The results indicated that the rotary forging could remarkably promote formability at elevated temperatures but not room temperature. For the 1 073 K and 1173 K samples, dynamic recrystallization led to a notable grain refinement effect and produced a typical basal texture. With the further increase of deforming temperature to 1 473 K, dislocation slip contributed the main deformation and the effect of grain refinement was weakened. The martensitic transformation took place during the cooling process of the 1 473 K sample, forming a strip type microstructure and a special texture different from basal texture.

Effects of NaBH4 Additions on Hydrogen Absorption by Nanostructured FeTi Powders

2008 ◽  
Vol 587-588 ◽  
pp. 921-925 ◽  
Author(s):  
Sofia F. Marques ◽  
Raquel A. Silva ◽  
Jose Brito Correia ◽  
Nobumitsu Shohoji ◽  
Carmen M. Rangel
Keyword(s):  
Hydrogen Absorption ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Low Cost ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gas Atmosphere ◽  
Scanning Electron

FeTi intermetallic powders are very promising media for reversible hydrogen storage. However, difficult activation treatments including annealing at elevated temperatures in high pressure H2 gas atmosphere are mandatory. In the present work nanostructured FeTi powders were produced and activated in situ at room temperature using mechanical alloying/milling (MA/MM) of pure metallic constituents, Fe and Ti, added with sodium borohydride. The resultant powders, FeTiHx, already H2 pre-charged, absorbed a significant amount of H2 but require optimization for reversible absorption/desorption. This system has one of the highest volumetric storage capacities and can be produced at low cost. Several parameters of the as-milled powders were controlled. The phase constitution of the reaction products was characterized by X-ray diffraction and scanning electron microscopy and the absorption isotherms of the activated powders were determined.

Tribological behaviour of AZ91D/ultra-high-temperature ceramic composites at room and elevated temperatures

2021 ◽  
pp. 135065012110100
Author(s):  
KT Sunu Surendran ◽  
A Gnanavelbabu
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Wear Test ◽  
X Ray Diffraction ◽  
Tribological Behaviour ◽  
X Ray ◽  
The Matrix ◽  
Scanning Electron ◽  
Ultra High Temperature

In this research work, the tribological behaviour of an AZ91D alloy and its composites reinforced with different titanium-based ultra-high-temperature ceramic particulates was investigated. Titanium-based ultra-high-temperature ceramic materials (5 wt%) such as titanium carbide, titanium boride and titanium nitride was used for the fabrication of three different composites, namely ATC, ATB and ATN, respectively. The proposed composites were prepared using a novel ultrasonic treatment-assisted stir-squeeze casting technique. Material characterization was performed using scanning electron microscopy and X-ray diffraction techniques. The porosity and hardness of the composites were determined prior to the wear test. In the pin-on-disc tribometer, the wear test was carried out at room temperature by varying the normal load (12.5–50 N) and the sliding speed (0.25–1 m/s). In addition, at a temperature of up to 200 °C, the tribological behaviour of the composites was assessed. The homogeneous distribution of ultra-high-temperature ceramic particles in the matrix was confirmed by the analysis of the microstructure using scanning electron microscopy images. The X-ray diffraction results showed that the reinforcement materials in the matrix were thermally stable. The hardness of the ATC, ATB and ATN was improved by approximately 31%, 33.8% and 29.6%, respectively. In comparison, at all wear testing conditions, ATB demonstrated superior tribological performance, while the performance of ATN was poor and ATC was moderate. Abrasion, oxidation and delamination were the wear mechanisms at room temperature. At elevated temperatures, oxidation, delamination, thermal softening and plastic deformation wear mechanisms were significant..

scholarly journals Studies of Optical, Dielectric, Ferroelectric, and Structural Phase Transitions in 0.9[KNbO3]-0.1 [BaNi1/2Nb1/2O3−δ]

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 35
Author(s):  
Blanca Yamile Rosas ◽  
Alvaro A. Instan ◽  
Karuna Kara Mishra ◽  
S. Nagabhusan Achary ◽  
Ram S. Katiyar
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Structural Phase ◽  
Cubic Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Wide Range

The compound 0.9[KNbO3]-0.1[(BaNi1/2Nb1/2O3−δ] (KBNNO), a robust eco-friendly (lead-free) ferroelectric perovskite, has diverse applications in electronic and photonic devices. In this work, we report the dielectric, ferroelectric, and structural phase transitions behavior in the KBNNO compound using dielectric, X-ray diffraction, and Raman studies at ambient and as a function of temperature. Analyses of X-ray diffraction (XRD) data at room temperature (rtp) revealed the orthorhombic phase (sp. Gr. Amm2) of the compound with a minor secondary NiO cubic phase (sp. Gr. Fm3m). A direct optical band gap Eg of 1.66 eV was estimated at rtp from the UV–Vis reflectance spectrum analysis. Observation of non-saturated electric polarization loops were attributed to leakage current effects pertaining to oxygen vacancies in the compound. Magnetization studies showed ferromagnetism at room temperature (300 K) in this material. XRD studies on KBNNO at elevated temperatures revealed orthorhombic-to-tetragonal and tetragonal-to-cubic phase transitions at 523 and 713 K, respectively. Temperature-dependent dielectric response, being leaky, did not reveal any phase transition. Electrical conductivity data as a function of temperature obeyed Jonscher power law and satisfied the correlated barrier-hopping model, indicating dominance of the hopping conduction mechanism. Temperature-dependent Raman spectroscopic studies over a wide range of temperature (82–673 K) inferred the rhombohedral-to-orthorhombic and orthorhombic-to-tetragonal phase transitions at ~260, and 533 K, respectively. Several Raman bands were found to disappear, while a few Raman modes such as at 225, 270, 289, and 831 cm−1 exhibited discontinuity across the phase transitions at ~260 and 533 K.

Magnetic Properties Of Iron/Silica Gel Nanocomposites

1988 ◽  
Vol 132 ◽  
Author(s):  
Robert D. Shull ◽  
Joseph J. Ritter ◽  
Alexander J. Shapiro ◽  
Lydon J. Swartzendruber ◽  
Llawrence H. Bennett
Keyword(s):  
Silica Gel ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Subsequent Treatment ◽  
Ferric Nitrate ◽  
Bragg Scattering ◽  
X Ray Diffraction ◽  
Iron Compounds ◽  
X Ray ◽  
Interconnected Pores

ABSTRACTHomogeneous gelled composites of iron and silica containing 5–30 wt. % Fe have been prepared by low temperature polymerization of aqueous solutions of ferric nitrate, tetraethoxysilane, and ethanol (with an HF catalyst). X-ray diffraction data, characterized by the presence of a diffuse scattering peak centered at 20≈24 degrees and the absence of any strong Bragg scattering from the iron-containing regions, indicates that these bulk materials are comprised of nanometer-sized regions of iron compounds embedded in a silica gel matrix. Scanning electron microscopy observations show that this matrix is characterized by the presence of many interconnected pores and that the size of these pores is related to the particle size of the Fe-containing regions. The paramagnetic nature of these materials at room temperature, as well as the small size of the iron-containing regions, is indicated by the appearance in many of the samples of only a high intensity central doublet in the 57Fe M6ssbauer spectra. The Mössbauer effect data demonstrates that the form of the iron can be changed by a subsequent treatment in an atmosphere of ammonia or hydrogen at elevated temperatures: for a 10 wt. % Fe sample treated with ammonia, only a central doublet was observed but with a much larger quadrupole splitting and isomer shift. Both of these subsequently treated materials became superparamagnetic at room temperature. In addition, magnetic susceptibility measurements indicate that the hydrogen treated material becomes a spin glass at low temperatures.

scholarly journals Microstructures and hardness of as-cast {C, Ta or Ti or Hf of Zr}-containing Cr-rich Niobium-based alloys candidate for uses at elevated temperatures

2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Patrice Berthod
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Chemical Properties ◽  
Inert Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Energy Dispersion Spectrometry ◽  
Very High ◽  
And Chemical Properties

Four alloys based on niobium and containing about 33wt.%Cr, 0.4wt.C and, in atomic content equivalent to the carbon one, Ta, Ti, Hf or Zr, were elaborated by classical foundry under inert atmosphere. Their as-cast microstructures were characterized by X-ray diffraction, electron microscopy, energy dispersion spectrometry and while their room temperature hardness was specified by Vickers indentation. The microstructures are in the four cases composed of a dendritic Nb-based solid solution and of an interdendritic NbCr2 Laves phase. Despite the MC-former behavior of Ta, Ti, Hf and Zr usually observed in nickel or cobalt-based alloys, none of the four alloys contain MC carbides. Carbon is essentially visible as graphite flakes. These alloys are brittle at room temperature and hard to machine. Indentation shows that the Vickers hardness is very high, close to 1000HV10kg. Indentation lead to crack propagation through the niobium phase and the Laves areas. Obviously no niobium-based alloys microstructurally similar to high performance MC-strengthened nickel-based and cobalt-based can be expected. However the high temperature mechanical and chemical properties of these alloys remain to be investigated. 

The surprising formation of structurally distorted ap-9-(o-tert-butylphenyl)-9-methylthiofluorene and its facile homolysis into sp-9-(o-tert-butylphenyl)-3-methylthiofluorene and sp-9-(o-tert-butylphenyl)fluorene

1999 ◽  
Vol 77 (5-6) ◽  
pp. 960-966 ◽  
Author(s):  
Yuqing Hou ◽  
Cal Y Meyers
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Dynamic Nmr ◽  
X Ray Diffraction ◽  
Similar Treatment ◽  
X Ray ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Acidic Conditions ◽  
Bulk Effect

The continued study of rotationally restricted 9-(o-tert-butylphenyl)fluorenes has provided surprising results. Treatment of sp-9-(o-tert-butylphenyl)-9-fluorenol (1) with ethanol or methanol under acidic conditions affords sp-9-(o-tert-butylphenyl)-9-ethoxyfluorene (2b) and sp-9-(o-tert-butylphenyl)-9-methoxyfluorene (3b), respectively, but similar treatment with methanethiol converts 1 into the rotamerically opposite ap-9-(o-tert-butylphenyl)-9-methylthiofluorene (4a). While all three products reflect reaction with inversion at C-9, 2b and 3b reflect subsequent rotation, which is not the case with 4a. X-ray diffraction shows 4a to be highly distorted and strained, but apparently favored thermodynamically over its sp rotamer. Homolysis of 4a is observed at room temperature, and at elevated temperatures accounts for the formation of sp-9-(o-tert-butylphenyl)fluorene (6b) and sp-9-(o-tert-butylphenyl)-3-methylthiofluorene (7c) as major products. X-ray diffraction shows 6b and 7c to be virtually devoid of distortion. Methylation of 6b via its anion also proceeds with inversion without rotation to form ap-9-(o-tert-butylphenyl)-9-methylfluorene (4c). Dynamic NMR unexpectedly showed that in these ap configurations 9-CH3 (of 4c) has a greater bulk effect than 9-CH3S (of 4a) in forcing the o-tert-butyl group into the fluorene plane.Key words: fluorene, rotamer, distortion, homolysis, carbanion, carbocation, radical.

scholarly journals The Crystal and Mesophase Structure of Hexakis(alkylsulfono)- benzene Homologues by X-Ray Diffractometry

1986 ◽  
Vol 41 (6) ◽  
pp. 855-860 ◽  
Author(s):  
N. Spielberg ◽  
Z. Luz ◽  
R. Poupko ◽  
K. Praefcke ◽  
B. Kohne ◽  
...  
Keyword(s):  
Room Temperature ◽  
Gradual Increase ◽  
Side Chain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Transition ◽  
Three Phase ◽  
Benzene Homologues ◽  
Hexagonal Columnar ◽  
Stacking Disorder

A powder X-ray diffractometer study of hexakis(tridecylsulfono)benzene (HASB13) has been carried out over the temperature range 20 to above 80 °C. In this range three phase transitions are observed by sharp discontinuities in the diffraction pattern indicating a solid-solid, solidmesophase, and mesophase-liquid transition. The mesomorphic phase is identified as a hexagonal columnar discotic mesophase, Dhd, with intercolumnar spacing of 25.7 Å and average stacking distance of 4.9 Å. Both distances are independent of temperature but there appears to be a gradual increase in the stacking disorder as the temperature is increased. The magnitude of the intercolumnar distance suggests a considerable degree of side chain disorder. A detailed X-ray diffraction study was also performed at room temperature on a single crystal of hexakis(propylsulfono) benzene (HASB3), which is not mesogenic. The results provide detailed information on the structure of HASB 3 which is used in the interpretation of HASB 13 results.

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