Papers by Keyword: Crystalline Phase

Abstract: The thermal stability and crystalline phases precipitated from the as-cast rods of the Cu50Zr50-based alloys with addition of Al or simultaneous addition of Al/Ti or Al/Ag elements were investigated using DSC, DTA and XRD. The value of
Tx, Trg and γ as a function of alloy composition shows a same trend, in which the Cu46Zr46Al8 alloy exhibits the largest value of
Tx, Trg and γ. However, this trend is different from the variation of the dc with alloy composition, in which the Cu42Zr42Al8Ag8 alloy has the largest dc for glass formation. Trg′ based on Tg/Tm has a good correlation with the critical diameter for glass formation in this alloy system. It was found that the alloy with higher GFA has more complex precipitated crystalline phases from the as-cast rod with a diameter larger than the critical diameter for glass formation.

Abstract: TiO2 nanoparticles were synthesized with using N2-diluted and O2-enriched coflow hydrogen diffusion flames. We investigated the effects of the flame temperature on the crystalline phases and particle characteristics of the TiO2 nanoparticles that were formed. For the higher temperature conditions, the maximum centerline temperatures that were measured were greater than approximately 1,600K, and TiO2 nanoparticles, which had spherical shapes with diameters of approximately 60nm, were synthesized. For the lower temperature conditions, the maximum centerline temperatures that were measured were less than approximately 1,600K, and the diameters of the nanoparticles that were formed had unclear boundaries that ranged from 35 to 50nm. From the XRD analyses, it was believed that the crystalline structures of the nanoparticles that were formed were divided into two types. For the higher temperature cases, the fractions of the TiO2 nanoparticles that were synthesized, which had anatase-phase crystalline structures, increased with the increase of the flame temperatures. On the contrary, for the lower temperature cases, the fraction of anatase-phase nanoparticles increased with the decrease of the flame temperatures.

Abstract: Magnesium aluminum silicate glass-ceramics were prepared by controlled heat treatment of base glass. The Al2O3 content was varied from 7.58 to 14.71mol % keeping total Mg content almost constant in the form of (MgO+MgF2). The crystalline phases were identified by X-ray diffraction technique while scanning electron microscopy was employed for finding the microstructure in the sample. The dielectric behaviour of the material was studied over the frequency range from 10-107 Hz and in the temperature range from 603 to 793K using impedance analyzer. X- ray diffraction studies revealed the formation of pure and mixed phases of MgSiO3, fluorophlogopite and Mg2SiO4 depending upon the alumina content. Mixed phase material has higher dielectric constant (e′), loss factor (e²) and dissipation factor (tand) than the single-phase material at lower frequencies. Dielectric constant (e′) decreases with frequency rather sharply up to 104Hz, and then remains nearly constant at higher frequencies up to 107Hz. However, tand first increases and then decreases with frequency passing through a broad peak. In all the cases e¢ and tan d are seen to increase with temperature. The activation energies for dipolar relaxation were calculated for all samples and were found to vary from1.77Joule/mole to 13.82Joule/mole with variation of alumina from 7.58 to 14.71mol %.

Abstract: TiO2 coating films of 50-200nm thickness were prepared by the sol-gel technique using hydrolysis of titanium isopropoxide (TIP) in an attempt to study structure and surface properties of anatase at ambient temperature. The anatase phase is exhibited by the XRD peak at 2θ'=25o with orientation in (101), the crystal parameters of XRD for TiO2 thin films (50-200 nm), were varied depending on the thickness of film and substrate type. An annealing temperature and annealing time had an effect on the film surface quality and exhibit porosity and aggregates in the films. The surface of TiO2 thin film showed cluster particles through SEM and the shrinkage rate on the film increased as a result of heat treatment during annealing process. The film was uniform and homogeneous under AFM investigate. EDS have determined the stochiometric ratio of TiO2 film.

Abstract: Titanium oxide films were prepared by reactive magnetron sputtering using continuous or pulsed DC sputtering power. The results of the structure and vitro hemocompatibility analyses indicated that non-stoichiometric titanium oxide films possess better hemocompatibility than LTIC and that the hemocompatibility of the titanium oxide films are evidently improved with the increase of rutile phase. This can result from the lower interface tension between titanium oxide films and biological substances and lower ratio of dispersive and polar component of the surface energy.