Plasma resonance in Pb$_{1-x}$Ag$_x$Te alloys

From the data of reflectance measurements for Pb$_{1-x}$Ag$_x$Te ($x$ = 0.001–0.007) alloy single crystals, the hole concentration and conductivity are calculated as functions of the Ag content. It is established that, for all of the samples, the plasma minimum is in the infra-red region and shifts to shorter wavelengths, as the Ag content is increased. In this case, the hole concentration and conductivity increase.