The yield stress-DLVO force relationship is obeyed by α-Al2O3 and alumina-coated TiO2 dispersions with adsorbed polyacrylate only if the yield stress and its corresponding zeta potential data were collected in the positively charged region. In this region, the underlying surface positive charge density of the particles exceeds the negative charge density of the polyacrylate. At this state the a...

We present recent experimental results of the use of electrostatic probes to characterize the differences seen in the low frequency instabilities (<200 kHz) in a laboratory Hall discharge operating in the ionization regime, i.e. at low voltages, where the ion current has not reached a maximum. Two very different wall materials are used in this study alumina and boron nitride. A wavelet decompos...

The adsorption of piperidine vapor on the hydrated alumina (alpha-Al2O3, corundum) (0001) surface was investigated using vibrational broad bandwidth and scanning sum frequency generation (SFG) spectroscopy. The interfacial vibrational signature in the C-H stretching region of piperidine at the alumina (0001) surface is shown to be a sensitive spectroscopic probe revealing the adsorption mechani...

the present study investigates the effect of different exposure densities on third grade iranian junior high school (ijhs) students’ efl development and retention. it also attempts to explore whether there is any differential performance due to type of post-exposure assessment tasks (recognition vs. written production). performances of five groups of learners receiving equal amount of exposure ...

Based on density functional methods, we investigate the origin of variations in electronic structures and dielectric constants of representative alumina polymorphs. We consider the most stable -Al2O3 and three metastable phases of alumina, , , and -Al2O3. Computed energy gaps are found to be in the order of , which can be understood based on electrostatic potentials at specific lattice sites; w...

We show that roughened surfaces of hyperbolic metamaterials scatter light preferentially inside the media, resulting in a very low reflectance. This phenomenon of fundamental importance, demonstrated experimentally in arrays of silver nanowires grown in alumina membranes, is consistent with a broad-band singularity in the density of photonic states. It paves the road to a variety of application...

Service life-time of alloys used in high temperature applications is often limited by corrosion. FeCrAl(Re) alloys are partially designed to form a protective α-alumina oxide scale at elevated temperatures in order to mitigate further oxidation. The scale growth commonly follows a parabolic rate law, which under a Wagnerian setting depends on transport of charged species; ions, vacancies and el...

a comprehensive study on the structural, electronic and nonlinear optical (nlo) properties of alumina nanostructures (al2o3)n with n = 2-5 belonging to the groups iii and vi dopants carried out by density functional theory. the nbo charges exhibit dopant atoms caused to the increasing charge transfer and introduces acceptor-donor model for nlo response of alumina nanostructures. under the influ...