Scaling behavior of different shapes of hysteresis loops and recoverable energy storage density in Na_(0.5)Bi_(0.5)TiO_(3), K_(0.5)Bi_(0.5)TiO_(3), and Na_(0.25)K_(0.25)Bi_(0.5)TiO_(3) ferroelectrics

In this work,the dependency of the polarization(P)-electric field(E)loop area A of lead free ferro-electrics Na_(0.5)Bi_(0.5)TiO_(3)(NBT), K_(0.5)Bi_(0.5)TiO_(3)(KBT),and Na_(0.25)K_(0.25)Bi_(0.5)TiO_(3)(NKBT)on the amplitude(E0)of the electric field is studied.Based on the nature of the hysteresis loop with increasing E0,the lnA versus lnE0 graph is divided into three stages and the scaling exponents of each stage are estimated.In the third stage,NBT,KBT,and NKBT show different shapes of P-E loops(square,slanted and pinched,respectively).Although,almost similar slopes in the third stage are obtained from the lnA versus lnE0 graphs of KBT and NKBT,the formation of pinched P-E loop of NKBT is discussed based on the current-time curve under a complete cycle of the applied electric field.The shape of the P-E loop also affects the recoverable energy storage density(Wrec)of the material.Similar to the scaling of A,the variation of lnWrec with lnE0 of NBT,KBT and NKBT are examined.Interestingly,three stages are only noticed in the lnWrec-lnE0 curve of pinched P-E loop(NKBT),whereas lnWrec linearly increases with lnE0 for square and slanted P-E loop.Such type of behavior of Wrec of NKBT is explained based on the reversible domain switching mechanism of the pinched P-E loop.

EMPIRICAL RELATIONSHIP BETWEEN RECOVERABLE STRAIN ENERGY AND TEMPERATURE FOR TiNi AND TiNiCu ALLOYS

Based on experimental study of the time dependence of the recoverable shape memory effect (SME)of shape memory alloys Ti50Ni50,Ti50Ni48Cu2 and Ti50Ni45Cu5 an empirical re- lationship between recoverable strain energy,U_r,and temperature,T.was derived as: U_r=U_o[1-exp(-mT_R^n)] where m—characteristic constant related to material,and n-shape-temperature sensitivity. The Johnson-Mehl-Aerami's phenomenological description of the time dependence of phase transformation was adopted to obtain a semiquantitative relationship associated with recoverable SME.between thermoelastic martensite transformation and temperature.This semiquantitative relationship is correspondent with the empirical expression.

A New Type of Power Clock for DSCRL Adiabatic Circuit

An asymmetry power clock,4 phase power clock supplying the power to the DSCRL(dual swing charge recovery logic) adiabatic circuit is presented.It is much simpler than the 6 phase power clock,symmetry power clock,used in the DSCRL adiabatic circuit.Although the 4 phase power clock is simpler,the DSCRL adiabatic circuit still shows good performance and high efficiency of energy transfer and recovery.This conclusion has been proved by the result of the HSPICE simulation using the 0 6μm CMOS technology.

HIGH TEMPERATURE SHAPE MEMORY EFFECT AND PRE-DEFORMATION FOR Ti_(50) Ni_(13) Pd_(37) ALLOY

The dependence of high temperature shape memory effect on the pre-deformation tempera- ture of the Ti_(50)Ni_3Pd_(37) alloy has been studied.This alloy,of which the reverse transformation start temperature on heating is 620 K,has both one-way and two-way shape memory effects. The maximum shape memory strain of the ahoy may be obtained under pre-deformation in the range of 620 to 640 K.This seems to be related to the minimum recoverable strain energy emerged from the above mentioned temperature range.