Search results for "Solid"
showing 10 items of 3575 documents
<title>Vibrational spectra of tungsten oxides with different lattice topology</title>
1997
It is determined that vibrations of linear chains -O-W-O-W- in tungsten-oxygen network are rather independent. The value of vibrational frequency is determined by asymmetry of O equals W - O bonds.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Photoelectric fields in doped lithium niobate crystals
2019
Photoinduced light scattering (PILS) in nominally pure stoichiometric and congruent lithium niobate single crystals (LiNbO3), and ones doped with B³⁺, Cu²⁺, Zn²⁺, Mg²⁺, Gd³⁺, Y³⁺, Er³⁺ cations was studied. All crystals have a relatively low effect of photorefraction and are promising materials for frequency conversion, electro-optical modulators and shutters. It was found that the photovoltaic and diffusion fields for some crystals have a maximum at a wavelength of 514.5 nm. All the crystals studied are characterized by a maximum of the integral intensity of the speckle structure of the PILS at a wavelength of 514.5 nm.
Solid-state electrochemical characterization of emissions and authorities producing Roman brass coins
2020
[EN] The voltammetry of immobilized particles (VIMP) is applied to describe the solid state electrochemistry of brass. This methodology, which involves sampling at the nanogram level, is applied to discriminate mints/authorities producing different Roman monetary emissions covering since the Republic (88 BCE) to Domitianus (55-96 CE) Upon attachment to graphite electrodes in contact with aqueous acetate buffer at pH 4.75, well defined voltarnmetric responses were obtained centered on Cu- and Zn-localized signals whose intensity can be correlated to EMP data, being sensitive to the contents of Zn (15-30 wt.%) and Sn (0.01-1.1 wt.%). Voltammetric data, combined with ATR-FTIR and FIB-PESEM/EDS…
Structure-property relationships in aromatic thioethers featuring aggregation-induced emission : Solid-state structures and theoretical analysis
2019
We describe in this paper a structure–property relationship study of aromatic thioethers with aggregation-induced emission (AIE) properties. We combine a structural analysis based on geometrical consideration with an in-depth analysis of the crystalline packing supported by quantum mechanical calculations. Our results allow us to correlate the enhanced fluorescence quantum yields with the significant increase of C–H⋯π and the decrease of π⋯π interactions in the solid state – a result which supports the well-accepted AIE mechanism quantitatively.
Relevant factors for the eco-design of polylactide/sisal biocomposites to control biodegradation in soil in an end-of-life scenario
2017
[EN] The eco-design considers the factors to prepare biocomposites under an end-of-life scenario. PLA/sisal biocomposites were obtained from amorphous polylactide and sisal loadings of 10, 20 and 30 wt% with and without coupling agent, and subjected to biodegradation in soil according to standard IS0846. Mass loss, differential scanning calorimetry and size-exclusion chromatography were used for monitoring biodegradation. A statistical factorial analysis based on the molar mass M-n, and crystallinity degree X-c pointed out the relevance and interaction of amount of fibre and use of coupling agent with the time of burial in soil., During the preparation of biocomposites, chain scission provo…
First bisphosphonate hydrogelators: potential composers of biocompatible gels
2020
Recently, investigation of hydrogels has gained ever increasing attention mostly because of their biomedical and pharmaceutical properties, and novel hydrogelators are constantly studied to find functional applications. Bisphosphonates (BPs) are well-known compounds applicable in different fields but are mostly used in clinics as drugs for bone-related diseases. In this study, a novel class of BP-hydrogelators together with a BP-organogelator was found, and the gelating abilities of the compounds were studied. Several techniques to analyze the structure and the properties of the formed gels were used, including solid state 13C and 31P CPMAS and solution state NMR spectroscopy, IR spectrosco…
Quantification of low levels of amorphous content in maltitol
2004
A method for the quantification of low levels of amorphous content of maltitol with hyper-DSC (high speed DSC) was developed. The method is based on the fact that the change of specific heat ( � Cp) at the glass transition is linearly proportional to the amorphous content. Twelve synthetic mixtures with various degrees of crystalline and amorphous maltitol were prepared. � Cp was determined at both fictive and
Crystallization and microstructural development of nickel-containing aluminosilicate glasses with cordierite stoichiometry
2001
Abstract The crystallization behaviour of two glasses with chemical compositions MAl2O4/SiO2=1/2.5, being MNi and equimolar mixtures of Mg and Ni, was investigated. Glasses were prepared by cooling samples melted at 1650 °C. During thermal treatment over the range of temperature up to 1200 °C both glasses were first crystallized to form a β-quartz solid solution, then transformed to α-cordierite or spinel depending on the amount of nickel. The temperatures of both the crystallization of β-quartz solid solution and its further transformation were also dependent on the nominal amount of nickel. Lower temperatures were found for glasses with a large amount of nickel. UV–Vis diffuse reflectanc…
Cobalt aluminate spinel-mullite composites synthesized by sol-gel method
1997
Abstract CoAl 2 O 4 spinel-mullite composites were prepared by double substitution of Al by Ti and Ni in stoichiometric 3:2 mullite. Gels with compositions 3(Al 2 − 2 x Co x Ti x O 3 )·2SiO 2 (x = 0.025, 0.05 and 0.2) and 3(Al 2 − 2 x M x O 3 )·2SiO 2 (x = 0.05; M = Co 2+ or Ti 4+ ) were synthesized by sol-gel techniques. The structure of the gels was investigated by infra-red spectroscopy. Heating gels at 750 °C produced an amorphous silicoaluminate network. The reaction sequence was investigated by differential thermal analysis, X-ray diffraction and ultraviolet-visible spectroscopy. All samples crystallized at temperatures lower than 1000 °C from the amorphous state. Al-Si spinel and/or …
Coefficient of thermal expansion and elastic modulus of thin films
1999
The coefficient of thermal expansion (CTE), biaxial modulus, and stress of some amorphous semiconductors (a-Si:H, a-C:H, a-Ge:H, and a-GeCx:H) and metallic (Ag and Al) thin films were studied. The thermal expansion and the biaxial modulus were measured by the thermally induced bending technique. The stress of the metallic films, deposited by thermal evaporation (Ag and Al), is tensile, while that of the amorphous films deposited by sputtering (a-Si:H, a-Ge:H, and a-GeCx:H) and by glow discharge (a-C:H) is compressive. We observed that the coefficient of thermal expansion of the tetrahedral amorphous thin films prepared in this work, as well as that of the films reported in literature, depen…