Materials Literature
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Actively passivated: The surprising recovery of the luminescence intensity between 200 and 300 K for CdSe quantum dots gives insight into the importance of the interaction between the capping layer and the nanocrystal semiconductor. The vial on the left is at 160 K while the brightly luminescing solution on the right…
The dielectric properties of BaTi 0.90 Ga 0.05 Nb 0.05 O 3 (BTGN) and Ba 0.60 Sr 0.40 TiO 3 (BST) ceramics prepared by the conventional solid‐state route have been investigated. Their relative potential for microwave (MW) tunable applications was assessed by the figure of merit ( K ) defined as K = [equation omitted]…
Polydimethylaminoethyl methacrylate (PDMAEMA) was used as a multidentate ligand to modify the surface of CdSe/ZnS core-shell colloidal quantum dots in toluene with trioctylphosphine oxide (TOPO) as the surface ligand. Adsorption of PDMAEMA was accompanied by release of TOPO. The process is free of agglomeration, and t…
We report a novel method to exfoliate and disperse single-wall carbon nanotubes (SWNT) into organic and aqueous solutions. The method is based on treatment of single-wall carbon nanotubes with a solution of hydroxylamine hydrochloric acid salt [(NH 2 OH)(HCl)] and does not require truncation of the tubes or surface ad…
This paper investigates the use of shape-memory polymer thin films in microelectromechanical systems (MEMS). shape-memory polymers possess the capacity to recover large-strain deformations by the application of heat and are candidates for small-scale transduction. The key advantages of shape-memory polymers are their…
An nitrogen-implanted p-type ZnO film has been grown on a Si substrate buffered with Si3N4 using radio-frequency magnetron sputtering. The Si3N4 buffer layer can effectively improve film stoichiometry and reduce the formation of oxygen vacancies compared to ZnO on Si. The electrical properties of the p-type ZnO films…
Magnetic properties of the main allotropic modifications of carbon (diamond, graphite, nanographite, nanotubes, and fullerenes) are described. Properties of nanocarbon are considered from the standpoint of the interrelation between structural imperfection and magnetic ordering. Experimental data on high-temperature fe…
ZnO nanowires were obtained through evaporation of zinc powders under a low temperature of 400 °C. These ZnO nanowires, in the diameter of ∼10 nm, were long and curved with lengths of tens of micrometers. High-resolution transmission electron microscopy showed these ZnO nanowires were mostly crystalline structure; how…
Abstract This paper surveys the recent achievements with thermoset rubber/layered silicate nanocomposites considering their production methods, cure characteristics, structure and basic properties (mechanical, thermal and barrier). It was shown that the properties of the “nanoreinforced” rubbers strongly depend on the…
The search of solutions to the habitacional crisis that exists in Latin America has favored to the use of the soil-cement-sisal, adobe reinforced like alternative material of building, in such sense, prevailing to determine the vulnerability of a building of this type, is for that reason that, the characterization of…
Dilatometric techniques were used to determine the start and finish transformation heating temperatures for a carbon steel (0.30% C - 1.5% Mn). The mechanical behavior of the steel was measured by torsion testing in the temperature range of 700 to 820 °C with holding times ranging from 1 to 30 min. The flow stress cur…
This paper compares industrial clinker and cement produced using conventional and alternative fuels (animal meal, tyres or a mixture of the two). The results show no relevant differences in terms of mineralogical composition between the clinker manufactured with alternative fuels and the product obtained using convent…
In the present study, the morphology and the impurity distribution were investigated in growth sectors formed around the [0001] axis of synthetic quartz crystals. Plates containing cylindrical holes and cylindrical bars parallel to [0001] were prepared by ultrasonic machining and further used as seed-crystals. The hyd…
In this work, the thermal stability of piezoelectric constants of PMN-PT ceramics in the tetragonal and rhombohedral phases were investigated in a wide range of temperatures. The results showed that the tetragonal PMN-PT presented higher thermal stability and, consequently, the temperature coefficients for the piezoel…
The objective of this study was evaluated the effect of heat treatment parameters on the pozzolanic activity of natural kaolin clays. The experimental design included three factors: kaolin type, temperature and time. Five types of Colombian kaolin clays were thermally treated from 400 to 1000 °C by 1, 2, and 3 hours.…
Different methods have been proposed in the literature to deposit PZT thin films. Among these, chemical based processes have been revealed as a promising preparation route due to their low cost processing and the facility for controlling the stoichiometry of complex systems. The objective of this work was to investiga…
Metallic nanowires have attracted much attention in the last years due to new phenomena such as quantum conductance and the existence of unexpected long interatomic distances attaining 0.3-0.5 nm. These large distances represented a challenge for physical interpretation. In this work we present experimental data from…
The suitable detection system of steel reinforcement corrosion in concrete structures contributes to the reduction of their maintenance costs. Method of steel electrical resistance represents non-destructive monitoring of steel in cementitious systems. Specially prepared and arranged test specimen of steel as a corros…
The combination between petrological data and historical documentation sources is necessary to establish an accurate methodology for the location of the original quarries of the stony materials used in a determinate historical building. The petrographical and petrophisical data correlation combined with a multivariate…