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Molecular dynamic calculations of the structure of a series of sodium silicate glasses, a common soda–lime glass, a sodium borosilicate glass and a sodium–potassium silicate glass were made. Calculated radial distribution functions are in good agreement with existing x-ray diffraction data and a previous MD calculation on silica glass. During the dynamical runs alkali and alkaline earth cations cluster around nonbridging oxygen atoms. In the borosilicate glass studied, the boron atoms enter the silica network and are tetrahedrally coordinated by oxygen. Other features of the simulated glasses include the coordination number of cations, the degree of inhomogeneity, the distribution of bridging and nonbridging oxygen atoms, the Si–O–Si bond angles, the ring structure, etc. Some preliminary diffusion studies will be presented.

Using the finite-element program MARC developed by MARC Analysis Corporation, thermal stresses are calculated for a simple sandwich seal and a bead seal under conditions of uniform cooling, reheating, and an isothermal hold and for a tempered glass plate. Results of the viscoelastic calculations are compared with previously obtained analytical solutions and with experimental stress measurements. The formalism for including viscoelastic material properties in the program is developed.

The purpose of this paper is to compare simple and efficient pairwise force fields for silica glass and assess their applicability for use in large

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The structure of seven sodium borosilicate glasses was calculated using molecular dynamics. Consistent with Zachariasen's rules of glass formation, silicon and boron were found to form a continuous near‐random network of SiO4, BO3, and BO4 polyhedra linked to each other at corners, whereas sodium ions occupied interstitial sites only. The most probable coordination of oxygen around sodium was five. There were roughly six oxygen atoms around an oxygen, nearly independent of the glass composition. The trigonal to tetrahedral conversion of boron with the addition of sodium agreed with the NMR results. The glasses studied showed no tendency to form boroxol groups.

The kinetics of energy transfer from antimony sensitizer to manganese activator in fluorophosphate phosphors has been studied. The transfer mechanism is identified as an exchange interaction by a comparison of the manganese concentration dependence of experimental quantum yield and emission decay curves with theoretical calculations for dipole-dipole, dipolequadrupole, and exchange mechanisms.The probability per unit time for the energy transfer by exchange is given by P=KB~ee"~~s in 8 cos y, where the empirical parameters are X= 48. 7 A 6 yacc~and I. = 0. 55 A. The antimony emission decay curve is found to be exponential in the absence of manganese acceptors, with a lifetime of 7. 65 + 0. 05 @sec. The subsequent manganese emission decay is found to fit the sum of two exponentials with the main component having a lifetime of 14.3+0. 5 msec and the minor component (which comprises only about 3/& of the total manganese emission) having a lifetime of 1.9 + 0. 1 msec.