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Wyszukujesz frazę "glasses" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
The structure of rarefied and densified PbSiO3 glass: a molecular dynamics study
Autorzy:
Bergmański, G.
Białoskórski, M.
Rychcik-Leyk, M.
Witkowska, A.
Rybicki, J.
Mancini, G.
Frigio, S.
Feliziani, S.
Powiązania:
https://bibliotekanauki.pl/articles/1954073.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska
Tematy:
oxide glasses
structure of glasses
ring analysis
MD simulations
Opis:
The paper is a molecular dynamics (MD) study of the structure of rarefied and densified lead-silicate glass of the PbSiO3 composition. Simulations have been performed in the constant volume regime for systems with densities of 3000, 4000, 5000, 5970 (normal density), 7000 and 8000kg/m3, using a two-body potential (Born-Mayer repulsive forces and Coulomb forces due to full ionic charges). All the systems were initially prepared as well equilibrated hot melts, and then slowly cooled down to 300K. The information on short-range correlations was obtained in a conventional way (from radial and angular distribution functions), while the middle-range order was studied via cation-anion ring analysis, using our new programme for basal ring determination. The structure of rarefied and densified glasses is compared with the structure of the same glasses under normal conditions. Moreover, the present results on PbSiO3 glass are compared with the corresponding data previously obtained for rarefied and densified PbGeO3 glass (Rybicki et al. 2001 Comput. Met. Sci. Technol. 7 91-112).
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 3; 393-412
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The structure of Pb-PbO-SiO2 glass via molecular dynamics simulation
Autorzy:
Rybicki, J.
Witkowska, A.
Bergmański, G.
Mancini, G.
Feliziani, S.
Powiązania:
https://bibliotekanauki.pl/articles/1954650.pdf
Data publikacji:
2022-01-20
Wydawca:
Politechnika Gdańska
Tematy:
lead-silicate glasses
oxide glasses
medium-range order
ring analysis
molecular dynamics simulations
Opis:
The paper is dedicated to a molecular dynamics (MD) study of the structure of partially reduced lead-silicate glass of composition 1Pb 1PbO 1SiO2. The simulations have been performed in the constant volume regime, using a two-body potential (Born-Mayer repulsive forces, and Coulomb forces due to full ionic charges). The system was initially prepared as a well equilibrated hot melt, and then slowly cooled down to 300K. The information on short-range correlations were obtained in a conventional way (from pair and angular distribution functions), while the medium-range order was studied via cation-anion ring analysis. In the paper, the short- and medium-range order in the simulated system is discussed and compared with the structure of a glassy completely reduced system, i.e. 2Pb 1SiO2 and unreduced one, i.e. 2PbO 1SiO2 glass.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 2; 243-256
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Short- and medium-range order in bismuth-silicate glasses: a solecular dynamics study
Autorzy:
Witkowska, A.
Rybicki, J.
Laskowski, R.
Mancini, G.
Feliziani, S.
Alda, W.
Powiązania:
https://bibliotekanauki.pl/articles/1954531.pdf
Data publikacji:
1999
Wydawca:
Politechnika Gdańska
Tematy:
structure of matter
oxide glasses
MD simulations
Opis:
We report on the results of classical molecular dynamics (MD) simulations of str ucture of amorphous 15 Bi2O3 85 SiO2 [% mol] and 40 Bi2O3 60 SiO2 [% mol], and their totally reduced forms, 15 Bi2 85 SiO2 [% mol], and 40 Bi2 60 SiO2 [% mol], respectively. The simulations have been perfo rmed in the isobaric-isoenthalpic ensemble, using a two-body interaction potential. The set of the potential parameters was constructed as a suitable com bination of the parameters which were previously proposed for pure Bi2O3, and SiO2. Both unreduced, and reduced sy stems were initially prepared as well equilibrated hot melts, and then slowly co oled down to 300K. The structural information from the MD simulations was obtained from radial and angular distribution functions, static structural factors, Voronoi polyhedra sta tistics, and ring analysis. The simulation results can be summarised as follows. In unreduced glass with 15% [mol] Bi2O3 contents, the silicon structural units (mainly regular tetrahedra) form continuous network, whereas in 40% [mol] Bi2O3 glass these units are disconnected. In both unreduced systems Bi ions have mainly six-fold oxygen co-ordination, and no dominating structural unit can be individuated. However, the distorted bismu th units form a continuous network. In both totally reduced glasses (15% Bi2 85% SiO2, and 40% Bi2 60% SiO2 [% mol]), the silica network is built entirely from corner shari ng SiO4 tetrahedra. The structure of the silica subsystem is similar to that of pure *-SiO2. After the reduction, the Bi-Bi co-ordination significantly increases, whereas the first neighbour distance decreases. Moreover, partial static structural fact ors for Bi-Bi pairs indicate that the medium-range order in reduced glasses exhi bits greater periodicity than in unreduced glasses. Neutral Bi atoms form small clusters within the silica matrix.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1999, 3, 2; 239-254
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A molecular dynamics study of the influence of chemical reduction on the structure of amorphous Germania
Autorzy:
Witkowska, A.
Murawski, L.
Bergmański, G.
Powiązania:
https://bibliotekanauki.pl/articles/1963001.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
oxide glasses
hydrogen reduction
molecular dynamics
structural modelling
Opis:
The contribution is dedicated to the molecular dynamics (MD) study of the structure of reduced germania glass of composition 1Ge 1GeO2. The work is inspired by a recent report on the formation of Ge clusters in hydrogen reduced germanate glasses containing oxides of heavy metals. The MD simulations have been performed in the microcanonical (NVE) ensemble, using a simple two-body Born-Mayer-Huggins interaction potential. A tendency of germanium atoms to agglomeration into clusters, observed in the present calculations, is compared with an analogous tendency of Bi and Pb atoms, observed previously in the xBi (1-x)GeO2 and xPb (1-x)GeO2 systems. The differences in the short and medium-range order in GeO2 system between the 1Ge 1GeO2 and GeO2 glasses are discussed.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 2; 273-281
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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