Abstract
The unique properties and great variety of relaxer ferroelectrics make them highly attractive in energy-storage and solid-state refrigeration technologies. In this work, lanthanum modified lead titanate ceramics are prepared and studied. The giant electrocaloric effect in lanthanum modified lead titanate ceramics is revealed for the first time. Large refrigeration efficiency (27.4) and high adiabatic temperature change (1.67 K) are achieved by indirect analysis. Direct measurements of electrocaloric effect show that reversible adiabatic temperature change is also about 1.67 K, which exceeds many electrocaloric effect values in current direct measured electrocaloric studies. Both theoretical calculated and direct measured electrocaloric effects are in good agreements in high temperatures. Temperature and electric field related energy storage properties are also analyzed, maximum energy-storage density and energy-storage efficiency are about 0.31 J/cm3 and 91.2%, respectively.
Highlights
Since the discovery of ferroelectrics, ferroelectric materials have been exploited in many applications, such as: piezoelectric energy harvesting, optical electronic devices, and etc[1,2,3]
Large electrocaloric effect (ECE) in PLT ceramics is achieved for the first time, maximum value of ΔT is about 1.67 K, and giant refrigeration efficiency is up to 27.4
Additional direct measured electrocaloric effects are analyzed, giant temperature change (1.67 K) is achieved, which indicates that PLT ceramics may be used in future solid-state refrigeration applications
Summary
Since the discovery of ferroelectrics, ferroelectric materials have been exploited in many applications, such as: piezoelectric energy harvesting, optical electronic devices, and etc[1,2,3]. In order to gain higher ΔT, many scholars pay attentions to thin films due to their large breakdown field[19,20,21] It is a well-known fact that thin films have advantages in small solid state cooling devices, but bulk materials play an important role on larger scale devices, such as: refrigeration[22,23]. Additional direct measured electrocaloric effects are analyzed, giant temperature change (1.67 K) is achieved, which indicates that PLT ceramics may be used in future solid-state refrigeration applications. The typical thermal response times along the sample thickness direction is a few milliseconds Within such a short period, a very fast equilibration of the temperature throughout the whole sample, including the electrodes, attached thermistor and wires, took place, but the equilibrated sample exchanges the heat on a much longer time scale to the surrounding bath
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