Dielectric relaxation behaviour of the $KH_2PO_4$ single crystal was studied in the vicinity of the ferroelectric phase transition temperature by use of the electric pulse excitation.
Induced polarization fluctuation was observed to be nearly independent of the pulse width ranging from 1㎲ to 1ms, and also of the pulse height from 50 mV to 5V. The resonance type dielectric response mixed with some complex relaxation was observed in the range of temperature from 133.4˚K to 122.1˚K, the phase transition temperature and no anomaly at the Curie point.
Dielectric constant measured from RC decay curve satisfies approximately the Curie-Weiss law with Curie constant of 263.7˚K and the Curie-Weiss temperature coincides with the transition temperature within the experimental error, showing that the phase transition is of the second order.
$KH_2PO_4$ 單結晶의 dielectric relaxation behaviour 를 electric pulse excitation 方法으로 强誘電性 相轉移 溫度 부근에서 調査하였다.
Polarization fluctuation 은 矩形波의 幅이 $1 \mu s$에서 1ms까지, 振幅이 50mV에서 5V까지의 變化에 대해 거의 같은 形態로 나타났으며 그 結果는 $KH_2PO_4$ 結晶體에서의 dielectric response가 주로 共振型임을 보여 주었다.
$133.4\,^\circ\!K$부터 相轉移 溫度인 $122.1\,^\circ\!K$ 사이에서는 relaxation 形態의 運動도 겹쳐서 매우 複雜한 樣相을 나타냈으며 相轉移点에서 不連續的인 變化를 보이지 않았다.
RC decay 曲線으로 부터 測定된 誘電常數는 대체적으로 Curie-Weiss law를 滿足시키며 Curie 常數는 $263.7\,^\circ\!K$이었다. Curie-Weiss 溫度는 實驗的 誤差內에서 실제 相轉移 溫度와 一致했으며 따라서 second order 의 相轉移임을 보여 주었다.
