Search results for "POWDER"
showing 10 items of 437 documents
Permanent magnetism in apoferritin-encapsulated Pd nanoparticles
2007
Pd nanoparticles have been prepared within the apoferritin cavity. X-Ray powder diffraction, transmission electronic microscopy and magnetization measurements have been used for characterizing the nanoparticles. The nanoparticles exhibit permanent magnetism at room temperature.
Structural and magnetic characterization of Pd nanoparticles encapsulated in apoferritin
2010
Pd nanoparticles exhibiting permanent magnetism at room temperature have been prepared within the apoferritin cavity. Pd nanoparticles in air and under an inert atmosphere were synthesized to study the influence of the aerobic and anaerobic conditions in the final magnetic properties. The surface of nanoparticles as well as the type of crystalline phase could determine the magnetic properties. X-ray powder diffraction, including Debye-function analysis, transmission electronic microscopy, and magnetization measurements have been used for characterizing the nanoparticles.
Evidence for a Double Doping Regime in Nd:YAG nanopowders
2009
Nanopowders of Yttrium Aluminium Garnet doped with neodymium (Nd:YAG) were investigated by X-Ray Absorption Fine Structure (XAFS) at the Nd LIII-edge in the 1.3 - 20.8 % doping range. XANES spectra appear similar in the full range of the Nd concentration. However, a significant decrease in the white line intensity of XANES is revealed as the quantity of Nd doping ions increases. Plotting the white line intensity as a function of Nd doping ions reveals two linear trends with two different slopes, identifying a threshold value where the neodymium concentration reaches 5 at.% This experimental finding provides support for the existence of a double doping regime in Nd:YAG nanopowders.
Beta-forging of Ti6Al4V titanium alloy powders consolidated by HIP: Plastic flow and strain-rate relation
2014
Ti6Al4V is probably the best known and studied titanium alloy, not only for aerospace applications. Nevertheless the deformation behavior still represents a challenge if any modification in the deformation process is required or introduced. This work deals with deformation behavior description of Ti6Al4V HIPped powders during high temperature deformation tests carried on in the Beta-region. Laboratory compression and tensile tests have been coupled with relaxation tests in order to achieve robust data about strain rate sensibility m-coefficient and activation energy Q. These results have been fitted for the assessment of a more general exponential deformation law. The final result is a “Dor…
Quantitative X-Ray Powder Diffraction Analysis of Some Feldspars Used as Raw Material in Ceramics
2001
Synthesis of Nd:YAG nanopowder using the citrate method with microwave irradiation
2010
Abstract Nd:YAG nanopowders were prepared using the Pechini process with microwave irradiation ( MWs ). A reference sample was also prepared using conventional heating. XRD pattern analysis showed that nanopowder obtained by means of conventional heating and calcination for 1 h at 900 °C has a structure made up of the garnet phase together with the hexagonal phase that disappeared after two additional hours of thermal treatment. The MWs powder calcined for 1 h consists of the single garnet phase. SAXS data analysis indicated that nanoparticles are characterized by a sharp interface. TEM investigation showed crystalline particles with remarkable agglomeration in both samples, although a more…
In-situ time resolved X-ray diffraction study of the formation of the nanocrystalline NbAl3 phase by mechanically activated self-propagating high-tem…
1999
The mechanically activated self-propagating high-temperature synthesis (MASHS) technique was used to produce a NbAl3 intermetallic compound. This process results from the combination of two steps: a mechanical activation of the Nb 3Al powder mixture which is followed by a self-propagating high-temperature synthesis (SHS) reaction, induced by the exothermal character of the reaction Nb3Al. An original experiment was designed to study in-situ the formation of the NbAl3 phase in the combustion front: time-resolved X-ray diffraction coupled with an infrared imaging technique and a thermocouple measurement were performed to monitor the structural and thermal evolution during the SHS reaction. Ow…
Crystal structures of new ternary compounds in RE–Pt–Pb and RE–Au–Pb systems (RE=rare earth metal)
2012
Abstract The crystal structures of the compounds RE 2 Pt 2 Pb (RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; Mo 2 FeB 2 structure type, space group P 4/ mbm , Pearson code tP10 ), REPtPb (RE = La, Ce, Pr, Nd, Sm; ZrNiAl structure type, space group P 6 ¯ 2 m , Pearson code hP9 ), RE 2 Au 2 Pb (RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; Er 2 Au 2 Sn structure type, space group P 4 2 / mnm , Pearson code tP20 ) and REAuPb (RE = Tm, Yb and Lu) were determined using X-ray powder diffraction.