Effect of Co⁶⁰ Gamma-Ray Irradiation on the Phase Transitions in NaNO₂

Abstract

Single crystals of NaNO₂ were irradiated with Co⁶⁰ gamma-ray of 1–6×10⁸ R at room temperature, then the dielectric constant ε₂₂ was measured in the vicinity of the transition temperatures. Both the ferroelectric to sinusoidal transition point (the Curie point) and the sinusoidal to paraelectric transition point (the Néel Point) monotonically decrease with gamma-ray irradiation. The ratio of the initial decreasing rate of the Curie point to that of the Néel point is 1.21. The sinusoidal phase widens with irradiation up to 2.5×10⁸ R, then it narrows with more irradiations. The transitions become sluggish with irradiation dose more than 2.5×10⁸ R.