Search results for "COATINGS"

Optical system for automatic color monitoring in heterogeneous media during vinification processes

2019

Abstract Wine is one of the most important food products worldwide. However, the application of technologies to the winemaking process can improve. An RGBC optical sensor, used to measure color intensity and shade, was developed and tested in real environments. It is able to measure samples without filtering by offering the color intensity and shade of a filtered sample. Color intensity can be measured within the range of 1.5 and 9.5 color points with an approximate 3% error. The model for shade can be applied to red wines with an approximate 1% error. It can operate directly in cellars under real operating conditions. It avoids collecting samples, and filtering and measuring in a spectroph…

Properties of trialkylamines as catalysts of resoles synthesis

2000

A series of the syntheses of phenol–formaldehyde resoles was carried out in the presence of trimethyl-, triethyl-, tripropyl-, and tributylamines and sodium hydroxide as catalysts for this process. The rate constants were calculated for the partial reactions identified in the synthesis. Also, the performance properties of the resins obtained and the hardened resin samples were estimated in simple tests. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 898–902, 2000

Systematical, experimental investigations on LiMgZ (Z= P, As, Sb) wide band gap semiconductors

2011

This work reports on the experimental investigation of the wide band gap compounds LiMgZ (Z = P, As, Sb), which are promising candidates for opto-electronics and anode materials for Lithium batteries. The compounds crystallize in the cubic (C1_b) MgAgAs structure (space group F-43m). The polycrystalline samples were synthesized by solid state reaction methods. X-ray and neutron diffraction measurements show a homogeneous, single-phased samples. The electronic properties were studied using the direct current (DC) method. Additionally UV-VIS diffuse reflectance spectra were recorded in order to investigate the band gap nature. The measurements show that all compounds exhibit semiconducting be…

Searching for hexagonal analogues of the half-metallic half-Heusler XYZ compounds

2008

The XYZ half-Heusler crystal structure can conveniently be described as a tetrahedral zinc blende YZ structure which is stuffed by a slightly ionic X species. This description is well suited to understand the electronic structure of semiconducting 8-electron compounds such as LiAlSi (formulated Li$^+$[AlSi]$^-$) or semiconducting 18-electron compounds such as TiCoSb (formulated Ti$^{4+}$[CoSb]$^{4-}$). The basis for this is that [AlSi]$^-$ (with the same electron count as Si$_2$) and [CoSb]$^{4-}$ (the same electron count as GaSb), are both structurally and electronically, zinc-blende semiconductors. The electronic structure of half-metallic ferromagnets in this structure type can then be d…

Enhanced Reflectivity Change and Phase Shift of Polarized Light: Double Parameter Multilayer Sensor

2022

Herein, the concept of point of darkness based on polarized light phase difference and absorption of light is demonstrated by simulations using low refractive index and extinction coefficient semiconductor and dielectric, and high refractive index nonoxidizing metal multilayer thin film structures. Several multilayer sensor configurations show great sensitivity to thickness and refractive index variation of the detectable material by measuring the reflectivity ratio {\Psi} and phase shift {\Delta}. Focus is on such multilayers, which have sensitivity to both parameters ({\Psi}, {\Delta}) in the visible spectral range, thus opening the possibility for further research on a new biomedical sen…

The 23rd international vacuum microbalance techniques conference

1990

Photoelectron spectroscopy of thin discontinuous metal films deposited onto a sapphire substrate

1995

Abstract The charging of small metallic clusters forming discontinuous gold and gallium films, condensed in vacuum onto an insulating substrate (sapphire), was experimentally studied by the method of ultraviolet photoelectron spectroscopy (UPS) for a photon energy of 5.4 eV. It seems that the charging is due to electron emission as well as to electron transfer from metal islands to the empty electron states in the metal-insulator interface.

A Comparative Ab Initio Thermodynamic Study of Oxygen Vacancies in ZnO and SrTiO3: Emphasis on Phonon Contribution

2013

Using a hybrid Hartree–Fock (HF)-DFT method combined with LCAO basis set and periodic supercell approach, the atomic, electronic structure and phonon properties of oxygen vacancies in ZnO and SrTiO3 were calculated and compared. The important role of a ghost basis function centered at the vacant site and defect spin state for SrTiO3 is discussed. It is shown that the use of hybrid functionals is vital for correct reproduction of defects basic properties. The Gibbs free energy of formation of oxygen vacancies and their considerable temperature dependence has been compared for the two oxides. These calculations were based on the polarizability model for the soft mode temperature behavior in S…

Valence band photoemission from thin iron films - A comparison of experimental and theoretical results

1998

Abstract In this contribution, we report on photoemission data from thin iron films on W(110) that have been carried out by means of spin-resolved photoelectron spectroscopy as well as Magnetic Circular Dichroism in valence band photoemission at the storage ring BESSY. These techniques give complementary information on the electronic and magnetic properties, such as exchange and spin–orbit splitting. We compare our experimental data to new photoemission calculations, which have been obtained in the framework of a fully relativistic one-step theory for ferromagnetic materials.

Competition between submonolayer ordering and multilayer adsorption: Studies of simple lattice gas models

1986

Abstract We model condensation of adatoms at a substrate surface by a semi-infinite simple cubic lattice gas system. While in the bulk there is just a nearest-neighbour attractive interaction, in the first layer adjacent to the surface we allow for a periodic potential due to the substrate with a period of two lattice spacings, or for a next-nearest-neighbour repulsive interaction mediated by the substrate. Hence order-disorder phenomena may occur in the first layer, while only gas-liquid condensation transitions can occur in layers further away from the substrate surface. The ground-state phase diagrams of this model are obtained exactly, while the behaviour at nonzero temperatures is obta…