Coexistence of Large Negative and Positive Electrocaloric Effects and Energy Storage Performance in LiNbO₃ Doped K_0.5Na_0.5NbO₃ Nanocrystalline Ceramics

Abstract

The electrocaloric effect (ECE) has been investigated in (1 − x)K 0.5 Na 0.5 NbO 3 −xLiNbO 3 (KNN-xLiN) nanocrystalline ceramics with compositions in the range of 0.01 ≤ x ≤ 0.05 by the indirect measurement using Maxwell's approach. The coexistence of the negative and positive ECEs has been achieved in all samples. The maximum values of negative and positive ECE were found to be −0.40 and 0.24 K for x = 0.01, −0.23 and 0.18 K for x = 0.03, and −0.13 and 0.29 K for x = 0.05, respectively. The maximum recoverable energy densities were found to be 0.12, 0.13, and 0.128 J/cm 3 with energy storage efficiencies of 30, 50, and 51% at an electric field of 45 kV/cm for x = 0.01, 0.03, and 0.05, respectively. The coexistence of the negative and positive ECEs with a high recoverable energy density in one material makes it a promising candidate for highly efficient, environmentally friendly cooling devices and energy-storage device applications.

Electrocaloric effect and pyroelectric performance in (K,Na)NbO3‐based lead‐free ceramics

“…[14][15][16][17][18][19][20][21][22] Recently, some investigations on ECE are also reported in the field of KNN-based materials. 10,12,[23][24][25][26] Li et al 12 obtained a ΔT of 0.41 K at 80°C in (Na 0.52 K 0.46 )(Nb 0.9 Sb 0.08 )O 3 -0.02LiTaO 3 ceramic via transition of O and T phases. Wang et al 10 also acquired a ΔT of 0.51 K at 77°C in 0.96(K 0.48 Na 0.52 )(Nb 0.95 Sb 0.05 ) O 3 -0.04Bi 0.5 (Na 0.82 K 0.18 ) 0.5 ZrO 3 ceramic in the vicinity of a phase transition of R and T phases.…”

Enhanced electrocaloric effect in compositional driven potassium sodium niobate‐based relaxor ferroelectrics

“…The ΔT value is almost doubled when the external applied electric field elevated from 40 to 65 kV/cm, proving the significant contribution of electric field to ECE performance. ceramics with FF or FP transitions [12,13,14,34,38,39,40,41]. It can be seen that the ΔT values of this work exceed most of the other KNN-based ceramics under the same or higher electric fields, illustrating that the ceramics prepared in this work are hopeful materials for practical refrigeration applications.…”

Large electrocaloric effect and energy storage performance of site-engineered lead-free Ba1-x (Bi0.5Li0.5) x TiO3 ferroelectric oxides

“…During the EC cyclic process, schematically shown in figure 1(a), the dipole orientation under electric field (E) lowers the entropy of the system by transferring the heat to the sink. Subsequently, the material is allowed to cool through the adiabatic process by the reorientation of dipoles upon withdrawal of the field and finally reaches the initial state by absorbing heat from the surrounding temperature [4,5]. Importantly, the change in entropy of the system is correlated to the strength and dynamics of polarization [6].…”