The influence of uniaxial compressive stress on the phase transitions and dielectric properties of NaNO2

• Dielectric constant (εε) of NaNO2 under uniaxial stress is studied.
• The stress–temperature phase diagrams of NaNO2 are determined.
• Unusual behavior of εε with σyyσyy is found.

The effect of uniaxial stress on dielectric properties of sodium nitrite (NaNO2) ferroelectric has been investigated. The real part of the dielectric susceptibility was measured at the frequency of 1 kHz without and on applying compressive uniaxial stress along different crystallographic directions using a uniaxial compress meter. Extraordinary changes in the dielectric constant of NaNO2 under the influence of applied uniaxial stresses were observed for the first time.The shifts of the phase transition points TiTi and TcTc under the uniaxial stresses σyyσyy and σzzσzz were investigated. The “uniaxial pressure–temperature” phase diagram of NaNO2 was obtained from these results. The observed phenomena were interpreted on the base of the phenomenological Landau theory of phase transitions in NaNO2 by taking into account the uniaxial compressive stress effect. A best agreement between the theoretical predictions and experimental results has been revealed.