Internal Friction of Simple Alkali Silicate Glasses Containing Alkaline‐Earth Oxides: I, Experimental Results

The internal friction of simple alkali silicate glasses to which systematic alkaline‐earth oxide additions were made was investigated. These additions produced two significant results: (1) The two peaks previously reported in alkali silicate glasses were shifted to higher temperatures and decreased in height and (2) a third peak was found in some glasses which became more pronounced with increasing alkaline‐earth oxide content. Internal friction measurements of alkali‐free silicate and phosphate glasses also are described. In these glasses, peaks were present which closely resembled those found in glasses containing alkali.