We present the results of studies of thermal expansion,heat capacity,permittivity,polarization and the influence of different thermal conditions on the intensive electrocaloric ffect(ECE),△T_(AD),in a commercial mult...We present the results of studies of thermal expansion,heat capacity,permittivity,polarization and the influence of different thermal conditions on the intensive electrocaloric ffect(ECE),△T_(AD),in a commercial multilayer capacitor based on doped BaTiO_(3).Investigations in a wide temperature range revealed one anomaly in the behavior of the physical properties at about 290 K characteristic for the relaxors.Direct measurements showed a high reversibility of ECE under equilibrium thermal conditions.Good agreement was found between the values of△T_(AD) determined by direct and indirect measurements at the electric field up to 15.4 kV/cm.Quasi-isothermal conditions lead,firstly,to decrease of large△T_(AD)≈0.94 K obtained in adiabatic conditions under E=308 kV/cm to 0.87 K,and,secondly,the appearance of a difference between the values of △T^(ON) and△T^(OFF) determined when the electric field is applied and removed.Using this phenomenon and changing the frequency of the periodic electric field,E=15.4 kV/cm,the efect of cooling was obtained equal to[(OT^(ON)+AT^(OFF))/2]_(max)=-0.032 K.The results obtained are useful for further development of the electrocaloric refrigeration technique without thermal switches.展开更多
基金funded by Russian Foundation for Basic Research,Government of Krasnoyarsk Territory,Krasnoyarsk Region Science and Technology Support Fund to the research,project no.16-42-240428 r_apartially financially supported by Government of Russian Federation,Grant 074-U01.
文摘We present the results of studies of thermal expansion,heat capacity,permittivity,polarization and the influence of different thermal conditions on the intensive electrocaloric ffect(ECE),△T_(AD),in a commercial multilayer capacitor based on doped BaTiO_(3).Investigations in a wide temperature range revealed one anomaly in the behavior of the physical properties at about 290 K characteristic for the relaxors.Direct measurements showed a high reversibility of ECE under equilibrium thermal conditions.Good agreement was found between the values of△T_(AD) determined by direct and indirect measurements at the electric field up to 15.4 kV/cm.Quasi-isothermal conditions lead,firstly,to decrease of large△T_(AD)≈0.94 K obtained in adiabatic conditions under E=308 kV/cm to 0.87 K,and,secondly,the appearance of a difference between the values of △T^(ON) and△T^(OFF) determined when the electric field is applied and removed.Using this phenomenon and changing the frequency of the periodic electric field,E=15.4 kV/cm,the efect of cooling was obtained equal to[(OT^(ON)+AT^(OFF))/2]_(max)=-0.032 K.The results obtained are useful for further development of the electrocaloric refrigeration technique without thermal switches.
