The availability of crystals of BaO made possible an investigation of the low frequency dielectric constant $\kappa$ of BaO. This has been measured over the frequency range 60 to 6×${10}^7$ cycles per second and the temperature range -25° to 60°C. Over these ranges $\kappa$ is about 34, which is quite different from the value of 14 frequently quoted. There is some evidence for a rise in $\kappa$ at the lowest frequencies. Data on dielectric loss is presented.

• Received 15 January 1951

DOI:https://doi.org/10.1103/PhysRev.83.801