Dielectric and electrical conductivity studies in potassium nitrite and potassium nitrate

The dc conductivity, the dielectric constant and the dielectric loss at 100 kHz and 3·6 GHz, have been measured for samples of potassium nitrite and potassium nitrate over a wide range of temperature. The dc conductivity and the dielectric constant show anomalies at −13°C and 40°C in a crystal of KNO₂ pulled from the melt. However, the dielectric anomaly at 40°C does not indicate a ferroelectric-paraelectric phase transition and the room temperature phase of KNO₂ seems not to be ferroelectric. The dc conductivity, the dielectric constant and loss measured in a randomly oriented single crystal, grown from aqueous solution, and a sample prepared from a melt of potassium nitrate, show anomalies at about 130°C on heating, and at about 124°C and 108°C on cooling. The dc conductivity, dielectric constant and loss value of the two samples of KNO₃ together with the frequency effect in a melt sample of KNO₃ are reported.