Investigation of Phase Transition Process in PT/PVDF(70)-TrFE(30)Ferroelectric Composite by Using Thermally Stimulated Current Method

The thermally stimulated current(TSC)behaviors of PT/PVDF(70)-TrFE(30)composite were investigated systematically.Two kinds of the ferroelectric phase(less organized ferroelectric and organized ferroelectric phase)coexist in the copolymer matrix at room temperature.The phase transitions can be identified clearly by poling sample above the Curie point and then cooling it to different temperatures.The result shows that the para-to-ferroelec trictransitions on cooling appear at 62℃and 50℃，and ferro-to-paraelectric transitions on heating at about 95℃ and 108℃，respectively.It also indicates that traps exist in ferroelectric phase but not in paraelectric phase of the copolymer.Lead titanate(PT) does not contribute to the current peaks within the experimental temperature range,but it makes Tc decrease and causes the current density increase compared with the pure copolymer.