Energy Additivity in Oxygen-containing Crystals and Glasses.

Abstract

In recent papers (2, 3) it has been shown that the energies of dissociation of simple and complex oxides into the gaseous ions of their component elements are approximately additive, conforming to the relationship where Ei is the "ionic dissociation energy" of the compound (or glass) M,M:,Ml,, . . * 0, and zy is a constant characteristic of element M. This constant may be thought of as the average contribution of one gram-atom of element M to the total energy of dissociation into gaseous ions of compounds or glasses in which each M atom is surrounded by a shell of oxygen atoms. No assumption regarding the nature of the forces (ionic or covalent) holding the M atoms to these oxygens is involved. Differences in the number of oxygens around each M in different compounds or glasses produce departures from strict additivity, but the deviations are not great. A large part of the magnitude of each % value can be attributed to the energies of formation of the gaseous ions, ill+" and 0-?, from the uncharged gaseous atoms, M and 0. In studying other factors affecting the magnitudes of the energy constants, it is of interest to subtract the contributions of these atomic ionization energies-in other words, to compute and compare energy constants,4, for dissociation into gaseous uncharged atoms, rather than ions.The 4 values are related to the % values by the following equation:Here u is the valence of the atom M in the compounds or glasses being considered and Qf designates the heat of formation, obtainable from Bichowsky and Rossini's valuable tabulation (1). Table 1 lists values of e& together with the values of eM from which they were computed by means of equation 2. Some additional €4 values are included, for elements for which the data on ionization energies of the gaseous elements required for the computation of % are not available. The equation used for

Synthesis and properties of cerium aluminosilicophosphate glasses

“…Following their work, G i was calculated for CeO 2 from the heats of formation for crystalline CeO 2 and gaseous Ce, and the density and molecular weight of CeO 2 [27,[29][30][31][32][33][34]. The density of each CASP and CAP glass was determined by Archimedes method using kerosene as the immersion fluid.…”

Anionic structure and elasticity of Na2O–MgO–SiO2 glasses

“…(2), Makishima and Mackenzie [13], Rocherulle et al [16] and Inaba et al [19] observed a good agreement between the calculated and measured Young moduli in their glasses. However, all V i values used in these literature were based on Pauling's ionic radii in octahedral coordination, and the old thermodynamic data [46,47] were adopted by some authors for their calculation of G i . Values of both V i and G i , on the other hand, have been recalculated by Lin and Liu [26], using Shannon's radii [48] with appropriate CN and the thermodynamic data listed in CRC Handbook of Chemistry and Physics (1992/1993).…”

Average single bond strength and optical basicity of Bi2O3–B2O3 and Sb2O3–B2O3 glasses

“…Kwak and Sung [19] have reported that the single bond strength of Bi-O bond is 214 kJ/mol. But according to Sun and Huggins [20] the dissociation energy of Bi 2 O 3 is 147 kcal/mol. It has been clarified from IR, Raman and X-ray diffraction analysis that coordination number of Bi 3+ does not change and remains high values of around six independent of glass composition in the Bi 2 O 3 -B 2 O 3 system [7,21].…”

“…[19] but it seems more reasonable since it is found on the basis of dissociation energy of the oxide while the value of Kwak and Sung is obtained using an approximation of relationship between bond strength and field strength of different cations. According to Sun and Huggins [20] the dissociation energy of Sb 2 O 3 is 164 kcal/mol and the single bond strength of Sb-O bond by using coordination number of Sb 3+ cation CN = 3 is 54.7 kcal/mol or 228.9 kJ/mol. Coordination number of Sb 3+ cation CN = 3 assumed in this paper is in agreement with IR and Raman spectral results reported by Terashima et al [7] as well as Sb K-edge EXAFS spectral results obtained by Ellison and Sen [22] for Sb 2 O 3 -B 2 O 3 glasses.…”