Intensive electrocaloric effect in triglycine sulfate under nonequilibrium thermal conditions and periodic electric field

Abstract

We present the results of both direct measurements and modeling of the intensive electrocaloric effect ΔTAD in ferroelectric triglycine sulfate under nonequilibrium thermal conditions and periodically varying electric field. In the narrow region around the phase transition temperature TC, a visible difference was observed between the electrocaloric responses at applying ΔTON and removal ΔTOFF of the constant electric field: |ΔTON| < |ΔTOFF| and |ΔTON| > |ΔTOFF| at T < TC and T > TC, respectively. The variation of the frequency and profile of the periodic electric field at T < TC allowed one to obtain the gradual decrease in the average temperature of the top of the sample compared to the bottom kept at the constant temperature. At low frequency electric field, qualitative agreement was found between the time dependences of the measured experimentally and calculated ΔT values.Experimental and modeling studies of electrocaloric effect ΔTAD in triglycine sulfate showed that the applying/removal of a periodic electric field to/from the bulk sample decreases the average value of the waiving temperature of the top Ttop compared to T = const of the bottom. Both frequency and duty cycle of the electric field impulses strongly affect Ttop.