Temperature-dependent nonlinear dynamic response of a KH2PO4cry

Thiourea[SC(NH2)2] in RLC circuit: Nonlinear dynamic response

“…Aluminium coating in the high vacuum evaporator was made onto the polished surfaces of the sample for electrodes and silver paste was used for lead wire contacts. RLC serial circuit was employed for detecting the nonlinear dynamic response signals [4,5], where input signals were derived from the function generator and amplifier, and output response signals from the voltage across the resistance R. Signals are observed either directly on the oscilloscope in the x-t mode or through the sample-and hold circuit by which (X,,X,+~) forms of signals are fed into the oscilloscope in the x-y mode operation.…”

“…Terms & Conditions of access and use can be found at http://www.tandfonline.com/ page/terms-and-conditions INTRODUCTION Although linear response theories are applied to understand the fluctuation dynamics of the phase transition the linear response theory completely fails when the critical system enters the chaotic region, and the nonlinear dynamic nature of the system becomes very important in understanding the critical dynamics of fluctuation [l]. Ferroelectric crystals such as Rochelle salt [2,3] and KDP crystals [4,5] are found to display the nonlinear dynamic responses near the phase transition temperatures. T h i o~r e a [ S C ( N H~)~] , a ferroelectric molecular crystal, has a very complex phase diagram consisted of the paraelectric phase above T1=202K, the ferroelectric phase below T,=169K, and the incommensurate phase in the wide range of temperature between T1=202K and TC=169I< [6].…”