XRD Results (xrd + result)

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Selected Abstracts

Syntheses, Crystal Structures, and the Phase Transformation of Octacyanometallate-Based LnIII,WV Bimetallic Assemblies with Two-Dimensional Corrugated Layers

Ai-Hua Yuan
Abstract The reactions between Ln(NO3)3nH2O and (Bu3NH)3[W(CN)8]H2O have led to two series of octacyanometallate-based complexes: Ln(H2O)5[W(CN)8] [Ln = La(1), Pr(2), Nd(3), Eu(4), Gd(5)] and Ln(H2O)4[W(CN)8] [Ln = Ho(6), Er(7), Tm(8), Lu(9)]. The crystal structures of 1,9 have two-dimensional corrugated layers in which the LnIII and WV centres are linked in an alternating fashion. Thermogravimetric (TG) and powder XRD results reveal the presence of a phase transformation in the LnIII,WV system with increasing atomic number of the LnIII atoms. [source]

A Novel Narrow Band Red-Emitting Phosphor for White Light Emitting Diodes

Sivakumar Vaidyanathan
Research on down conversion phosphor materials is the key for the development of solid-state lighting (SSL). Especially finding alternative red phosphor for white light emitting diodes (LEDs) based on blue or near ultraviolet (NUV) LEDs is important research task. In this view, we have synthesized a series of Eu3+ -substituted La2W2,xMoxO9 (x=0,2, in step of 0.3) red phosphor and characterized by X-ray diffraction (XRD) and photoluminescence. XRD results reveal a phase transition from triclinic to cubic structure for x>0.2. All the compositions show broad charge transfer (CT) band due to CT from oxygen to tungsten/molybdenum and red emission due to Eu3+ ions. Select compositions show high red emission intensity compared with the commercial red phosphor under NUV/blue ray excitation. Hence, this candidate can be a possible red phosphor for white LEDs. [source]

Hydrothermal Synthesis and Characterization of KxNa(1,x)NbO3 Powders

Jun-Hai Lv
NaNbO3, KNbO3, and KxNa(1,x)NbO3 powders were successfully prepared by the hydrothermal method. The phase of the products was identified to be orthorhombic structure by X-ray diffraction (XRD) technique, and the XRD results revealed that the x value of the KxNa(1,x)NbO3 gradually increased with the increase in the ratio of K+ to Na+ in alkaline solution. The morphology and the microstructure were investigated by scanning electron microscopy, energy-dispersive spectroscopy, and transmission electron microscopy, and the results indicated that the ratio of K+ to Na+ in the solution had a great effect on the morphology and the size of products. Na0.5K0.5NbO3 with morphotropic phase boundary composition could be synthesized when the molar ratio of K+ to Na+ was between 4:1 and 6:1 in the solution. A possible formation mechanism of the KxNa(1,x)NbO3 crystal was also proposed based on the experimental results. [source]

Evaluation of polymethacrylic ionomer as compatibilizers for MCPA6/clay composites

Tongfei Wu
Abstract The compatibilization effects provided by polymethacrylic ionomer (PMMA ionomer) on monomer-casting polyamide6 (MCPA6)/clay (pristine sodium montmorillonite) composites were studied in this work. The PMMA ionomer used in this study was sodium polymethacrylate ionomer (PMMA Na+ -ionomer), which is a copolymer of methyl methacrylate and sodium methacrylate, prepared using emulsion polymerization. MCPA6/clay/PMMA Na+ -ionomer composites were prepared by in situ anionic ring-opening polymerization (AROP) of ,-caprolactam (CLA). X-ray diffraction (XRD) and transmission electron microscopy (TEM) plus rheological measurement were used to characterize those composites. The results indicated that PMMA Na+ -ionomer is a good compatibilizer for this system. With increasing PMMA Na+ -ionomer content, a better dispersion of clay layers was successfully achieved in the MCPA6 matrix. Furthermore, differential scanning calorimetry (DSC) and XRD results indicated that well dispersed silicate layers limit the mobility of the MCPA6 molecule chains to crystallize, reduce the degree crystalline, and favor the formation of the ,-crystalline form of the MCPA6 matrix. 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

pH-sensitive alginate/soy protein microspheres as drug transporter

Hua Zheng
Abstract The complex microspheres based on alginate (AL) and soy protein isolate (SPI) were prepared by solution blending and then Ca2+ crosslinking, and their function as drug carrier was explored as well. The effects of composition on the structures of microspheres were studied, and the XRD results proved the miscibility between components. Meanwhile, FTIR results suggested that such miscibility was driven by strong hydrogen bonding. Especially, the complex microsphere with equal content of AL and SPI had the best miscibility by morphological analysis, shown as a smooth and uniform surface of SEM images. The controlled release function of the complex microspheres was verified using theophylline as a drug model, that is, the swelling and drug release were affected by pH conditions and showed obvious differences under given pH of stomach, intestine, and colon. Moreover, the intestine and colon may be optimal site for prompt release of drugs. Except for the attribution of AL component to pH sensitivity, the complex microspheres also inherited the bioactivity of SPI component, which may lower irritants of drug to the tissues in body. 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source]

Flexible nanocrystalline-titania/polyimide hybrids with high refractive index and excellent thermal dimensional stability

Guey-Sheng Liou
Abstract In this study, a novel synthetic route was developed to prepare polyimide,nanocrystalline,titania hybrid optical films with a relatively high titania content (up to 50 wt %) and thickness (20,30 ,m) from soluble polyimides containing hydroxyl groups. Two series of newly soluble polyimides were synthesized from the hydroxy-substituted diamines with various commercial tetracarboxylic dianhydrides. The hydroxyl groups on the backbone of the polyimides could provide the organic,inorganic bonding and resulted in homogeneous hybrid solutions by controlling the mole ratio of titanium butoxide/hydroxyl group. AFM, SEM, TEM, and XRD results indicated the formation of well-dispersed nanocrystalline-titania. The flexible hybrid films could be successfully obtained and revealed relatively good surface planarity, thermal dimensional stability, tunable refractive index, and high optical transparency. A three-layer antireflection coating based on the hybrid films was prepared and showed a reflectance of less than 0.5% in the visible range indicated its potential optical applications. 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1433,1440, 2010 [source]

Effect of Heat Treatment on Far Infrared Emission Properties of Tourmaline Powders Modified with a Rare Earth

Dongbin Zhu
Far infrared materials were prepared by precipitation method using natural tourmaline (XY3Z6Si6O18(BO3)3W4, where X is Na+, Ca2+, K+, or vacancy; Y is Mg2+, Fe2+, Mn2+, Al3+, Fe3+, Mn3+, Cr3+, Ti4+ or Li+; Z is Al3+, V3+, Cr3+, or Mg2+; and W is OH,, F,, or O2,) powders and cerium nitrate as raw materials. The results of Fourier transform infrared spectroscopy (FTIR) show that rare earth Ce can enhance the far infrared emission properties of tourmaline. Through characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the mechanism by which rare earth Ce acts on the far infrared emission property of tourmaline was systematically studied. The XPS spectra show that the Fe3+ ratio inside tourmaline powders after heat treatment can be raised by doping Ce. Moreover, it is showed that Ce3+ is dominant inside the samples but its dominance is replaced by Ce4+ outside. In addition, XRD results indicate the formation of CeO2 crystallites during the heat treatment and further TEM observations show they exist as nanoparticles on the surface of tourmaline powders. Based on these results, we attribute the improved far infrared emission properties of Ce-doped tourmaline to the enhanced unit cell shrinkage of the tourmaline arisen from the oxidation of Fe2+ (0.074 nm in radius) to Fe3+ (0.064 nm in radius) inside the tourmaline caused by the redox shift between Ce4+ and Ce3+. [source]

Use of different alkylammonium salts in clay surface modification for epoxy-based nanocomposites

G. Ipek Nakas
Layered silicates become widely used reinforcement material in the polymer nanocomposite production in recent years due to their high aspect ratio, ease of processing, and low cost. In this present study, the aim was to evaluate the usability of a raw clay source (Resadiye, Turkey) in the production of epoxy/clay nanocomposites and to investigate the effects of different surface modifiers. For this purpose, raw Na,montmorillonite clay was first purified and then surface modified by using different types of alkylammonium salts: tetramethyl ammonium bromide, benzyl triethyl ammonium bromide, dodecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide, and octadecyl trimethyl ammonium bromide. Purification and surface modification of this clay were evaluated by using the following analyses; X-ray diffraction (XRD), cation exchange capacity (CEC), particle size distribution, and dissolved organic content. These analyses simply indicated that surface modification increased both interlayer spacing between the silicate layers and CEC of the clay. These improvements were directly proportional with the chain length of the surface modifier. Nanocomposite specimens were produced by adding 0.5 wt% surface modified clay into the epoxy matrix. These specimens were characterized by XRD, Si-mapping facility of SEM, and mechanical tests. XRD results indicated an exfoliated structure whereas Si-mapping showed the uniform distribution of clay particles in epoxy, leading to improved mechanical properties, for instance more than 100% increase in fracture toughness of the neat epoxy specimen. POLYM. COMPOS., 2009. 2008 Society of Plastics Engineers [source]

Investigation of mineral composition of oil shale

Dong-Mei Wang
Abstract The aim of this paper is to identify the mineral composition of oil shale from different locations and relate it to their interval of occurrence. Thermogravimetric analysis (TGA), diffuse reflectance infrared Fourier transforms spectroscopy (DRIFTS) and X-ray diffraction (XRD) methods were used for this invetigation. Hydrogen peroxide was used as the oxidant to eliminate the influence of organic matter in TGA. DRIFTS results indicated that most of the kerogen is in aliphatic hydrocarbon form and the peak of hydrocarbon nearly disappeared after oxidation. XRD results indicated that quartz, muscovite, kaolinite and calcite are the dominant minerals. Longkou and Changchun oil shale samples contain high percentage of calcite (12.9 and 11.7% CO2 respectively) while Fushun and Huadian oil shale samples contain less than 6% CO2. Especially, in Fushun oil shale sample, the content is below 3%. Kaolinite is found in Fushun oil shale sample, while muscovite is only found in Huadian oil shale sample. Integration of the XRD, DRIFTS and TGA results of the oil shale samples from different locations has provided a better way of mineral composition identification. Copyright 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]