In this work,a phenomenological model is applied to describe the magnetocaloric effect for the La_(0.75)Ca_(0.25)MnO_(3)system near a second-order phase transition from a ferromagnetic to a paramagnetic state.Based on...In this work,a phenomenological model is applied to describe the magnetocaloric effect for the La_(0.75)Ca_(0.25)MnO_(3)system near a second-order phase transition from a ferromagnetic to a paramagnetic state.Based on this model,it can predict the values of the magnetocaloric properties from calculation of magnetization as a function of temperature under different external magnetic fields.The magnetic entropy change reaches a peak of about 5.39 J/(kg·K)at 257 K upon 4 T applied field variation.TheΔSM distribution is much more uniform than that of gadolinium,which is desirable for an Ericson-cycle magnetic refrigerator.展开更多
The electrocaloric(EC)effect accompanied with the ferroelectric to paraelectric phase transition in(111)-oriented PbMg_(1/3)Nb_(2)/3O_(3)(PMN)is investigated.It is shown that the largest change TDis 0.37 K in 3 kV/cm ...The electrocaloric(EC)effect accompanied with the ferroelectric to paraelectric phase transition in(111)-oriented PbMg_(1/3)Nb_(2)/3O_(3)(PMN)is investigated.It is shown that the largest change TDis 0.37 K in 3 kV/cm electric field shift near the Curie temperature of 221 K;that is,the cooling TDper unit field(MV/m)is 1.23×10^(-6) m·K/V.This value is significantly larger,and comparable with the value of 0.254×10^(-6) m·K/V for PbZr_(0.95)Ti_(0.05)O_(3)thin film under larger electric field shift ED=30 kV/cm.Thus,the EC effect of(111)PMN single crystal provides cooling solutions at low temperatures,and opens more opportunities for practical application in cooling systems.展开更多
The magnetocaloric effect (MCE) achieved for La_(0.7)Sr_(0.3)MnO_(3)/Ta_(2)O_(5) composites has been investigated. The maximum value of magnetic entropy change of La_(0.7)Sr_(0.3)MnO_(3) composites is found to decreas...The magnetocaloric effect (MCE) achieved for La_(0.7)Sr_(0.3)MnO_(3)/Ta_(2)O_(5) composites has been investigated. The maximum value of magnetic entropy change of La_(0.7)Sr_(0.3)MnO_(3) composites is found to decrease slightly with the further increasing of Ta_(2)O_(5) concentration. It is shown that La_(0.7)Sr_(0.3)MnO_(3)/Ta_(2)O_(5) composites exhibit much more uniform magnetic entropy change than that of gadolinium. Moreover, the results indicate that the temperature range between 100 K and 400 K can be covered using the La_(0.7)Sr_(0.3)MnO_(3)/Ta_(2)O_(5) composites. Therefore, MCE makes the composites promising for room-temperature magnetic cooling applications.展开更多
文摘In this work,a phenomenological model is applied to describe the magnetocaloric effect for the La_(0.75)Ca_(0.25)MnO_(3)system near a second-order phase transition from a ferromagnetic to a paramagnetic state.Based on this model,it can predict the values of the magnetocaloric properties from calculation of magnetization as a function of temperature under different external magnetic fields.The magnetic entropy change reaches a peak of about 5.39 J/(kg·K)at 257 K upon 4 T applied field variation.TheΔSM distribution is much more uniform than that of gadolinium,which is desirable for an Ericson-cycle magnetic refrigerator.
文摘The electrocaloric(EC)effect accompanied with the ferroelectric to paraelectric phase transition in(111)-oriented PbMg_(1/3)Nb_(2)/3O_(3)(PMN)is investigated.It is shown that the largest change TDis 0.37 K in 3 kV/cm electric field shift near the Curie temperature of 221 K;that is,the cooling TDper unit field(MV/m)is 1.23×10^(-6) m·K/V.This value is significantly larger,and comparable with the value of 0.254×10^(-6) m·K/V for PbZr_(0.95)Ti_(0.05)O_(3)thin film under larger electric field shift ED=30 kV/cm.Thus,the EC effect of(111)PMN single crystal provides cooling solutions at low temperatures,and opens more opportunities for practical application in cooling systems.
文摘The magnetocaloric effect (MCE) achieved for La_(0.7)Sr_(0.3)MnO_(3)/Ta_(2)O_(5) composites has been investigated. The maximum value of magnetic entropy change of La_(0.7)Sr_(0.3)MnO_(3) composites is found to decrease slightly with the further increasing of Ta_(2)O_(5) concentration. It is shown that La_(0.7)Sr_(0.3)MnO_(3)/Ta_(2)O_(5) composites exhibit much more uniform magnetic entropy change than that of gadolinium. Moreover, the results indicate that the temperature range between 100 K and 400 K can be covered using the La_(0.7)Sr_(0.3)MnO_(3)/Ta_(2)O_(5) composites. Therefore, MCE makes the composites promising for room-temperature magnetic cooling applications.
