Acoustic delay line

Claim 1

In an acoustic delay line of the type having signal converting elements on the surface of a glass body for converting an input electric signal into an acoustic signal and an output acoustic signal into an electric signal, the improvement comprising that said body of glass consist of the following composition in wt. percent: SiO2 60-70 K2O + Na2O 2-6 Na2O < or = 0.5 Sb2O2 + As2O3 < or = 1.5 B2O3 < 5 Al2O3 <15 and the remainder not less than 25 percent by weight of the following constituents: PbO 0-5 CaO 0-10 BaO0-25 MgO 0-5 ZnO 0-15 CdO 0-20 SrO 0-15 Bi2O3 0-20 said glass also satisfying the requirement that -5 X 10 6< Sigma i Alpha ixi <+5 X 10 6, where Alpha i is the temperature coefficient of the rate of propagation in the range of 20*-70* C for the oxide component i as listed above for the corresponding oxides and xi is the molar fraction of said component in the glass.