V.A. Kreisberg, V.P. Rakcheev, T.V. Antropova
Microporous substructure in porous glasses: dynamic and equilibrium
approaches
Journal of Porous Materials (2004) (in print)
ABSTRACT
Porous glasses produced by the leaching of two-phase alkali
borosilicate glasses have been studied by dynamic and equilibrium
methods for diagnostics of pore morphology. It has been detected the
availability of microporous substructure with some kinds of adsorbing
micropores of diameter 0.3-2 nm including ultramicropores of molecular
size in porous glasses with transporting pores of mean diameter from 4
to 15 nm. The polymodal nanoporous structure of porous glasses detected
by kinetic mass spectral method of gas diffusion diagnostics (DD-method)
at low temperatures is consistent with the results obtained from
analyzing equilibrium desorption isotherms of nitrogen, oxygen and argon
at 77.5 K by different calculation techniques including an equilibrium
method of gas desorption at low partial pressures (LPED-method).
Micropore volume in porous glasses is equal to 6-18% from total pore
volume. The dependence of nanoporous morphology of porous glasses on
conditions of their production and composition has been established. The
diffusion and equilibrium characteristics of different molecules
(nitrogen, oxygen, argon) varying in molecule size and quadrupole moment
value have been determined for primary and secondary porous
substructures of porous glasses at liquid nitrogen temperature at the
first time.
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