Search results for "Silicate"

Behaviour of advanced tritium breeder pebbles under simultaneous action of accelerated electrons and high temperature

2017

The authors greatly acknowledge the technical and experimen-tal support of O. Valtenbergs and L. Avotina (Institute of Chemical Physics, University of Latvia). The work is performed in the frames of the University of Latvia financed project No. Y9-B044-ZF-N-300, “Nano, Quantum Technologies, and Innovative Materials for Eco-nomics”.

Modeling glass materials

2005

Abstract Structural and dynamic properties of silicate melts and glasses (SiO 2 and its mixtures with Na 2 O and Al 2 O 3 ) are derived from Molecular Dynamics simulations and compared to pertinent experimental data. It is shown that these mixtures exhibit additional intermediate order as compared to pure silica, where the characteristic length scales stem from the tetrahedral network structure. While sodium ions show much faster diffusion through percolating channels than the silicon and oxygen ions forming the surrounding network, aluminium ions are incorporated into the network (leading to tricluster formation) and do not show such an enhanced mobility.

Scale-up low-cost synthesis of bimodal mesoporous silicas

2005

Porous pure and doped silicas with pore sizes at two length scales (meso/macroporous) have been prepared through a large scale one-pot surfactant assisted reproducible procedure by using a simple template agent and starting from non-expensive sodium silicate as silicon source. Together with the relative low-cost of the reagents we have used, the simplicity of this method, which moreover is scalable and provides high yields, could be a strong argument for considering its suitability for the production of bimodal porous silicas. Additionally, we present a simple chemical scheme that allows directing the synthesis towards different related materials including both bimodal nanoparticulated meso…

EPR study of Ce3+ luminescent centers in the Y2SiO5 single crystalline films

2017

Abstract The work reports results of EPR investigation of the Ce3+ incorporation in the Y2SiO5 and (Y,La)2SiO5 single crystalline films (SCFs), grown by liquid phase epitaxy method. The Ce3+ content determined from EPR spectra varied between 0.49 and 0.65 at. % in Y2SiO5 SCFs and strongly increased up to 1.9 at. % in (Y,La)2SiO5 SCF, suggesting a positive role of the La dopant in the incorporation of the Ce3+ ions into Y2SiO5 host. The EPR study showed the presence of only one type of Ce3+ centers (Ce1) corresponding to the localization of Ce3+ ions in the seven–fold coordinated positions of the Y2SiO5 host. No Ce2 center spectra (six-fold coordinated Ce3+ positions) were detected in films …

Structural model of gelation processes of a sodium silicate sol destabilized by calcium ions: combination of SAXS and rheological measurements

2005

This study deals with the physico-chemical processes involved in the formation of basic fractal silica gels derived from a sodium silicate sol destabilized by calcium ions. Using small-angle X-ray scattering and dynamic rheological measurements, structural and viscoelastic properties have been investigated in situ during aggregation and gelation processes. The experimental results lead to a consistent model that describes the structural features and aggregation mechanisms involved in the formation of these gels.

Multistep Crystallization Pathways in the Ambient‐Temperature Synthesis of a New Alkali‐Activated Binder

2021

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 MNi 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…

Slow dynamics in ion-conducting sodium silicate melts: Simulation and mode-coupling theory

2005

A combination of molecular-dynamics (MD) computer simulation and mode-coupling theory (MCT) is used to elucidate the structure-dynamics relation in sodium-silicate melts (NSx) of varying sodium concentration. Using only the partial static structure factors from the MD as an input, MCT reproduces the large separation in relaxation time scales of the sodium and the silicon/oxygen components. This confirms the idea of sodium diffusion channels which are reflected by a prepeak in the static structure factors around 0.95 A^-1, and shows that it is possible to explain the fast sodium-ion dynamics peculiar to these mixtures using a microscopic theory.

Novel silver-based nanoclay as an antimicrobial in polylactic acid food packaging coatings.

2010

This paper presents a comprehensive performance study of polylactic acid (PLA) biocomposites, obtained by solvent casting, containing a novel silver-based antimicrobial layered silicate additive for use in active food packaging applications. The silver-based nanoclay showed strong antimicrobial activity against Gram-negative Salmonella spp. Despite the fact that no exfoliation of the silver-based nanoclay in PLA was observed, as suggested by transmission electron microscopy (TEM) and wide angle X-ray scattering (WAXS) experiments, the additive dispersed nicely throughout the PLA matrix to a nanoscale, yielding nanobiocomposites. The films were highly transparent with enhanced water barrier …

Stability of Halloysite, Imogolite, and Boron Nitride Nanotubes in Solvent Media

2018

Inorganic nanotubes are attracting the interest of many scientists and researchers, due to their excellent application potential in different fields. Among them, halloysite and imogolite, two naturally-occurring aluminosilicate mineral clays, as well as boron nitride nanotubes have gained attention for their proper shapes and features. Above all, it is important to reach highly stable dispersion in water or organic media, in order to exploit the features of this kind of nanoparticles and to expand their applications. This review is focused on the structural and morphological features, performances, and ratios of inorganic nanotubes, considering the main strategies to prepare homogeneous col…