Structural development of tellurite glasses with the addition of LizO and NazO has been studied using infrared, Raman, and X-ray photoelectron spectroscopies. The increase in intensity of the peak at 755 cm-' in the infrared spectra as compared to the peak at 620 cm-' suggests the transformation of Te04 building units to Te03 pyramids with the addition of alkali oxide. Proposed structural change is further supported by the strong compositional dependence of the 755-cm-' peak in the Raman spectra as well as by the formation of a shoulder in the 0 l s peak of X-ray photoelectron spectra. In contrast to alkali silicate glasses, formation of nonbridging oxygens with the addition of alkali oxide is not observed. [

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Atomic force microscopy was used to measure forces acting on a sharp tungsten tip as it was brought into contact with silica and 30 mol% binary alkali silicate glasses. Experiments were performed in controlled atmospheres and under vacuum. Attractive forces and liquid-layer thicknesses were found to vary markedly between the glasses, and heterogeneity was observed on the binary alkali silicates analyzed in vacuo. Air or wet carbon dioxide exposure resulted in the penetration of the tip into a soft surface layer on the alkali silicates. In addition, liquid layer formation on the alkali silicates was found to be promoted by exposure to water vapor in the order lithium < sodium < potassium. X-ray photoelectron spectroscopy indicated that reaction between the potassium silicate surface and water vapor occurred on exposure to only torr (1 torr = 1.33 X 102 Pa) water. Surface segregation and leaching of potassium occurred under the same conditions.