X-ray Diffraction Results (x-ray + diffraction_result)

Distribution by Scientific Domains

Selected Abstracts

Role of oxygen vacancies in the coloration of 0.65Pb(Mg1/3Nb2/3)O3 -0.35PbTiO3 single crystals

Zhiguo Xia
Abstract The coloration and oxygen vacancies in 0.65Pb(Mg1/3Nb2/3)O3 -0.35PbTiO3 (PMN-PT(65/35)) (starting composition) single crystals grown by a so-called modified Bridgman technique were investigated in this paper. Light yellow and dark brown colored crystals were generally observed for the typical as-grown PMN-PT(65/35) single crystals. X-ray diffraction results demonstrated that they were both of pure perovskite structure, but good electric properties were only obtained for the light yellow crystal. X-ray photoelectron spectroscopy (XPS) was used to investigate the electronic structure of its components. The O 1s photoelectron spectra of the dark brown colored crystals located at the higher binding energy side, which meant the existence of the more oxygen vacancies. It accordingly led to the formation of the low valence cations associated with the coloration of the crystals, which is also testified by the obtained X-ray photoelectron spectra of Ti and Nb. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Low-temperature phase transformation and phonon confinement in one-dimensional Ta2O5 nanorods

Rupesh S. Devan
The thermochromic phase transformations of one-dimensional Ta2O5 nanorods have been analyzed at elevated temperatures ranging from 80 to 300,K. The nanorods, grown in a large-area high-density array, are 14,22,nm wide and approximately 500,nm long. The array contained ,93.5% of the orthorhombic (,) phase and ,6.5% of the tetragonal (,) phase. Low-temperature X-ray diffraction results showed complex and polymorphic thermochromic phase transformations of the ,(001), ,(101) and ,(103) lattice planes of the nanorods, which incorporate (i) ,-to-, (,,,), (ii) ,,,,, and (iii) ,,, phase transitions. In comparison with the Raman scattering of three-dimensional bulk powder and two-dimensional thin films of Ta2O5, there were concurrent Raman blue- and redshifts in the one-dimensional Ta2O5 nanorods, indicating that the molecular vibrations of the nanorods were confined owing to the reduction of size and dimension. [source]

Effects of two different maleic anhydride-modified adhesion promoters (PP-g-MA) on the structure and mechanical properties of nanofilled polyolefins

P. Eteläaho
Abstract The effects of adhesion promoter properties on the structure and mechanical behavior of nanoclay-filled polyolefin nanocomposites are presented. Two different maleic anhydride-modified polypropylenes having varying maleic anhydride content and molecular weight were used. The influence of these parameters on the performance and morphology of the prepared polypropylene and high density polyethylene-based nanocomposites was examined by mechanical testing, X-ray diffraction, and electron microscopy. The low molecular weight adhesion promoter seemed to be effective in both matrices in relation to mechanical property enhancements, whereas its high molecular weight counterpart performed well only in polyethylene matrix. X-ray diffraction results and examination of morphology revealed that the intercalation and the dispersion of the nanoclay were more even in both matrices when the low molecular weight adhesion promoter with a higher maleic anhydride content was used. On the other hand, the use of high molecular weight adhesion promoter led to a less uniform dispersion but also to a greater amount of exfoliated clay particles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

Collagen nanofilm immobilized on at surfaces by electrodeposition method

Xiudong Yang
Abstract A simple electrodeposition method is presented for the preparing of collagen nanofilms (EAT) on anodic oxidized titanium surfaces (AT). The nanofilms were observed by scanning electron microscopy and atomic force microscopy. Functional TiOx layers with anionic groups of PO4, SO4 and OH were investigated on the AT surface by X-ray photoelectron spectroscopy; X-ray diffraction results indicated that the AT surface was composed mainly of anatase and rutile. The bioactive electrodeposited TiOx layers on the AT surface showed lower water contact angles and higher surface energy than pure titanium surfaces (CT) and displayed higher collagen molecule immobilization. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source]

A Novel Hybrid Method of Sol,Gel and Ultrasonic Atomization Synthesis and Piezoelectric Properties of SrBi4Ti4O15 Ceramics

Zhijun Xu
SrBi4Ti4O15(SBTi) powders were synthesized by a novel hybrid method of sol,gel and ultrasonic atomization. TiO2 particle was used as a starting material to replace other expensive soluble titanium salts. X-ray diffraction results showed that the pure-phase SBTi powders were obtained at 700°C for 2 h, which is much lower than the calcination temperature (800°,850°C) required in solid-state reactions. The ceramics sintered at 1100°C for 1 h exhibited 94.5% of relative density and a piezoelectric coefficient of 21 pC/N. The results showed that this hybrid method could lead to an attractive method for the industrial fabrication of SBTi materials. [source]

Effect of clay on the morphology of binary blends of polyamide 6 with high density polyethylene and HDPE- graft -acrylic acid

Zhengping Fang
Polyamide 6 (PA6)/HDPE/organo-bentonite (Oclay) and PA6/HDPE- grafted -acrylic acid (PEAA)/Oclay nanocomposites were prepared via melt compounding. The influence of Oclay on the morphology of composites was investigated. Scanning electron microscopy results revealed the size of the dispersed HDPE, and PEAA phase decreased with increasing Oclay content. Transmission electron microscopy and X-ray diffraction results revealed that the Oclay was predominately intercalated with some evidence of partial exfoliation. The majority of Oclay platelets were concentrated in the PA6 phase and in the interfacial region between PA6 and HDPE (PEAA). The Oclay platelets played the role of coupling species between the two polymers, increasing the interaction of the two phases in certain extent. These results were proved by FTIR and positron annihilation lifetime spectroscopy. Consequently, apparent emulsifying effect was induced. A schematic mechanism of the apparent compatibilization effect was presented. POLYM. ENG. SCI., 47:551,559, 2007. © 2007 Society of Plastics Engineers. [source]

Polypropylene/Clay nanocomposites: Effect of compatibilizer on the thermal, crystallization and dynamic mechanical behavior

Sangeeta Hambir
Polypropylene (PP)/clay nanocomposites are prepared using different grades of PP, compatibilizers, and organically modified clays. The melt intercalation of the PP is carried out in presence of a compatibilizer. The nanocomposites are characterized using various techniques for the structure and properties. X-ray diffraction results indicate well-defined structures. Thermogravimetric analysis indicates improved thermal stability of PP/clay nanocomposites. Isothermal crystallization studies carried out using differential scanning calorimeter illustrate enhanced crystallization of PP in all the nanocomposites. Optical microscopic study demonstrates that the nanocomposites can be crystallized at higher temperatures, exhibiting well-defined birefringent structures. The dynamic mechanical analysis reveals higher storage moduli over a temperature range of ,400C to 1200C for nanocomposites, and the extent of increase in the storage modulus is dependent on the type of compatibilizer used. [source]

Thermal and morphological properties of high-density polyethylene/ethylene,vinyl acetate copolymer composites with polyhedral oligomeric silsesquioxane nanostructure

Patrícia Scapini
Abstract The demand for improved properties of common polymers keeps increasing, and several new approaches have been investigated. In the study reported here, composites with a polymer matrix comprising a blend of high-density polyethylene with ethylene,vinyl acetate copolymer (EVA), and with polyhedral oligomeric silsesquioxane (POSS) as a nanostructure, were processed and characterized in terms of their thermal and morphological properties. For the preparation of the composites, the concentrations of the blend components (0, 50 and 100 wt%) and of the POSS (0, 1 and 5 wt%) were varied. X-ray diffraction results indicated that the presence of EVA in the composites led to the appearance of crystalline domains at lower POSS concentrations. Transmission and scanning electron microscopy showed that samples with 1 wt% of POSS had a homogeneous distribution in the polymer matrix with average dimensions of ca 150 nm. However, the formation of aggregates occurred in samples with 5 wt% of POSS. Differential scanning calorimetry and thermogravimetic analyses indicated that the POSS did not affect the melt and degradation temperatures of the polymer matrix. POSS underwent aggregation at higher concentrations during the composite processing, indicating a solubility limit of around 1 wt%. The presence of EVA in the composite favors POSS aggregation due to an increase in the polarity of the polymer matrix. Copyright © 2009 Society of Chemical Industry [source]

6,-Methyl- B -norandrostenedione

L. C. R. Andrade
The title compound, C19H26O2, a B -norandrogen with a 6,-methyl group, is a recently identified and experimentally tested potent new aromatase inhibitor. It shares structural and physicochemical similarities both with the natural substrate of the enzyme, androstenedione, and with exemestane, another potent aromatase inhibitor having a 6-methylidene group. X-ray diffraction results indicate that the B -nor molecule and exemestane have nearly the same oxygen,oxygen and methyl,methyl separations, though they have distinct configurations of the hydrophobic groups at the 6-position. These structural comparisons allow correlations to be inferred between the active site geometry of the molecules and the aromatase inhibition power of the studied compound. [source]

Starch-based nanocomposites by reactive extrusion processing

Sathya B Kalambur
Abstract Nanocomposites with unique material properties have been prepared from synthetic plastics and nanosilicates (nanoclay) until now, but not from biopolymers such as starch. The primary challenge in making biopolymeric nanocomposites is to achieve strong adhesion between nanoclay and polymer matrix. For the first time nanocomposites with superior properties have been successfully made from starch-polycaprolactone (PCL) blends in the presence of montmorillonite (MMT) nanoclay. Reactive extrusion results showed that addition of a modified nanoclay at 3 % wt level increased elongation almost fourfold over that of pristine starch,PCL blends. X-ray diffractions results showed dispersion of clay in the polymer matrix. The nanocomposites have better solvent-resistance properties because of resistance to diffusion offered by clay platelets in the polymer matrix. Copyright © 2004 Society of Chemical Industry [source]