LOW-FREQUENCY DIELECTRIC ANOMALY IN THE INCOMMENSURATE PHASE OF NANO2

Low frequency dielectric constant of sodium nitrite (NaNO2) has been m easured near the incommensurate-to-paraelectric phase transition tempe rature (T-i) and the incommensurate-to-ferroelectric phase transition temperature (T-c) at the frequency range below 100 Hz. Beside the well -known dielectric anomalies at T-i and T-c, an additional anomaly in t he imaginary part of dielectric constant just below T-c is observed at the frequency below 10 Hz. The dielectric behavior is dependent on th e thickness of the sample and the thermal history of heating and cooli ng cycles. This phenomenon is attributed to the pinned discommensurati ons which may have slow relaxational characteristics.