Obiekt

Tytuł: THE STRUCTURE OF THE FIRST CO-ORDINATION SHELL OF Pb ATOMS IN LEAD-SILICATE GLASSES :A MOLECULAR DYNAMICS STUDY

Twórca:

Rybicka Anna

Typ zasobu:

artykuł

Współtwórca:

Rybicki Jarosław, Witkowska Agnieszka, Feliziani Sandro, Mancini Giorgio

Abstrakt:

The structure of lead-silicate glasses, although being investigated for over sixty years, remains still controversial. One of the open questions is the structure of the lead subsystem: what are the basic structural units like, and how are they interconnected. In the literature the appearance of [PbO4]n, or [PbO3]n chains is reported even in the glasses of the same stoichiometry. In order to elucidate the problem of contradicting experimental findings, extensive molecular dynamics (MD) simulations in the isobaric-isoenthalpic (NpH) ensemble of the structure of lead-silicate glasses have been performed in the whole range of glassformation. The atoms were assumed to interact by a two-body Born-Mayer-Huggins interaction potential with full ionic charges. The potential parametrization was taken from Damodaran et al. [Phys. Chem. Glasses, 31, 212 (1990)1. The simulation box contained about 3000 atoms. For each composition an equilibrated ming Pb03 pyramids with the Pb atom in the vertices or in the middle of an al ost flat triangle formed from forapical oxygens of three different SiO4 tetrahedra. Another of all Pb atoms can be qualified as vertices ofrather distorted square pyramids. The remaining of lead atoms have neighbourhoods difficult to classify. For x 0.67 only a few Pb atoms were identified as remaining in the front of a face of a SiO4 tetrahedron. Most of the Pb atoms are placed in the vertices of edge sharing square PbO4 pyramids. Our MD results are compared with available experimental data. 0.1 X 0.33, about of all Pb atoms is either placed in the front of the faces of the SiO4 tetrahedra, forapical oxygens of three different SiO4 tetrahedra. Another of all Pb atoms can be qualified as vertices of rather distorted square pyramids. The remaining of lead atoms have neighbourhoods difficult to classify. For x 0.67 only a few Pb atoms were identified as remaining in the front of a face of a SiO4 tetrahedron.

Miejsce wydania:

Poznań

Wydawca:

OWN

Format:

application/pdf

Identyfikator zasobu:

oai:lib.psnc.pl:501

Język:

eng

Kolekcje, do których przypisany jest obiekt:

Data ostatniej modyfikacji:

2014-07-29

Data dodania obiektu:

2014-05-22

Liczba wyświetleń treści obiektu:

199

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https://lib.psnc.pl/publication/594

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