Energy-storage properties and electrocaloric effects of Pb(1-3x/2)LaxZr0.85Ti0.15O3 antiferroelectric thick films

1-µm-Pb(1-3x/2)LaxZr0.85Ti0.15O3 (PLZT) antiferroelectric (AFE) thick films with x = 0.08, 0.10, 0.12, and 0.14 were deposited on LaNiO3/Si (100) substrates by a sol-gel method. The dielectric properties, energy-storage performance, electrocaloric effect, and leakage current behavior were investigated in detail. With increasing La content, dielectric constant and saturated polarizations of the thick films were gradually decreased. A maximum recoverable energy-storage density of 38 J/cm3 and efficiency of 71% were achieved in the thick films with x = 0.12 at room temperature. Moreover, a large reversible adiabatic temperature change ∆T = 25.0 o C was presented in the thick films with x = 0.08 at 127 o C at 990 kV/cm. All the samples had a lower leakage current density below 10- 6 A/cm2 at room temperature. These results indicated that the PLZT AFE thick films could be a potential candidate for applications in high energy-storage density capacitors and cooling devices

A giant electrocaloric effect of a Pb0.97La0.02(Zr0.75Sn0.18Ti0.07)O3 antiferroelectric thick film at room temperature

A 2-µm-Pb0.97La0.02(Zr0.75Sn0.18Ti0.07)O3 (PLZST) antiferroelectric (AFE) thick film with tetragonal structure was deposited on LaNiO3/Si (100) substrates via a sol-gel technique. The electrocaloric effect (ECE) of the PLZST thick film is investigated under the functions of external electric field and temperature. Giant ECEs (∆T = 53.8 oC and ∆S = 63.9 J·K-1·kg-1) are received at 5 oC, which is attributed to a field-induced AFE to ferroelectric (FE) phase transition. Moreover, a large ∆T of above 30 oC is remains at temperature range from 5 oC to 25 oC. The maximum electrocaloric coefficient (ξmax = 0.060 K·cm/kV) and refrigeration efficiency (COP = 18) of the film are also obtained at 5 oC. At room temperature, the values of ∆T, ∆S, COP and ξmax are 35.0 oC, 39.0 J·K-1·kg-1, 14 and 0.039 K·cm/kV at 900 kV/cm, respectively. The AFE thick films with giant ECEs are promising candidates for applications in cooling systems at room temperature

Enhanced energy-storage performance and electrocaloric effect in compositionally graded Pb(1−3x/2)LaxZr0.85Ti0.15O3 antiferroelectric thick films

The compositionally graded multilayer Pb(1−3x/2)LaxZr0.85Ti0.15O3 (PLZT) antiferroelectric (AFE) thick films were deposited on LaNiO3/Si (100) substrates by using a sol–gel method. The effect of gradient sequence on dielectric properties, energy-storage performance, and electrocaloric effect (ECE) was investigated in detail. It is found that the compositionally graded films exhibited a significant enhancement in dielectric properties, energy-storage performance and ECE, which was, in contrast to the single-composition PLZT film, contributed by the strain and the gradient of polarization near the interfaces between the adjacent layers. A recoverable energy-storage density of 44 J/cm3 and efficiency of 71% was obtained in the up-graded PLZT AFE thick film at 1950 kV/cm. A giant reversible adiabatic temperature change of ∆T=28 °C at room temperature at 900 kV/cm was also achieved in the up-graded film. Moreover, all the thick films displayed a small leakage current density below 10−6 A/cm2 at room temperature. Thus, the compositionally graded PLZT AFE thick films with a large recoverable energy-storage density and a giant ECE could be a potential candidate for the applications in high energy-storage density capacitors and cooling devices