Large Electrocaloric Responsivity and Energy Storage Response in the Lead-Free Ba(GexTi1−x)O3 Ceramics

Abstract

Ferroelectric property that induces electrocaloric effect was investigated in Ba(GexTi1−x)O3 ceramics, known as BTGx. X-ray diffraction analysis shows pure perovskite phases in tetragonal symmetry compatible with the P4mm (No. 99) space group. Dielectric permittivity exhibits first-order ferroelectric-paraelectric phase transition, confirmed by specific heat measurements, similar to that observed in BaTiO3 (BTO) crystal. Curie temperature varies weakly as a function of Ge-content. Using the direct and indirect method, we confirmed that the adiabatic temperature change ΔT reached its higher value of 0.9 K under 8 kV/cm for the composition BTG6, corresponding to an electrocaloric responsivity ΔT/ΔE of 1.13 × 10−6 K.m/V. Such electrocaloric responsivity significantly exceeds those obtained so far in other barium titanate-based lead-free electrocaloric ceramic materials. Energy storage investigations show promising results: stored energy density of ~17 mJ/cm3 and an energy efficiency of ~88% in the composition BTG5. These results classify the studied materials as candidates for cooling devices and energy storage applications.

Enhanced Energy Storage Performance and Efficiency in Bi0.5(Na0.8K0.2)0.5TiO3-Bi0.2Sr0.7TiO3 Relaxor Ferroelectric Ceramics via Domain Engineering

“…However, lead is hazardous to the environment and human health due to its toxicity, which has motivated the development of alternative lead-free materials. In recent years, lead-free perovskite-structured (ABO 3 ) RFEs, such as BT [25][26][27], BNT [6,[28][29][30][31], BFO [32][33][34], and other lead-free perovskite RFEs, such as Bi 4 Ti 3 O 12 [35], Sr 1.25 Bi 2.75 Nb 1.25 Ti 1.75 O 12 [36], and Sr 0.6 Ba 0.4 Nb 2 O 6 [37] based materials with boosted energy storage performance, have been reported for applications in energy storage devices.…”

Influence of Grain-Growth Inhibitors on Modified (Ba,Sr)(Sn,Ti)O3 for Electrocaloric Application

“…To realize solid-state cooling based on the EC effect, various material systems have been explored so far. Besides lead-containing EC material systems such as PbZr 0.95 Ti 0.05 O 3 (PZT) [ 2 ], PbSc 0.5 Ta 0.5 O 3 (PST) [ 3 ] and (1 − x)Pb(Mg 1/3 Nb 2/3 )O 3 –xPbTiO 3 (PMN-PT) [ 4 ], investigations on lead-free EC material systems based on ferroelectric BaTiO 3 [ 5 , 6 , 7 , 8 ] as well as the relaxor ferroelectrics Bi 0.5 Na 0.5 TiO 3 [ 9 , 10 , 11 ] and K 0.5 Na 0.5 NbO 3 [ 12 , 13 ] have also been widely reported.…”

Improved Energy Storage Density and Efficiency of Nd and Mn Co-Doped Ba0.7Sr0.3TiO3 Ceramic Capacitors Via Defect Dipole Engineering

“…In recent years, lead-free dielectric capacitors have received significant attention, and a great deal of research has been carried out to enhance energy storage properties due to lead toxicity and environmental issues. Lead-free dielectrics, such as BaTiO 3 (BT) [15,24,25], Bi 0.5 Na 0.5 TiO 3 (BNT) [13,[26][27][28][29], BiFeO 3 (BFO) [1,23,30], and K 0.5 Na 0.5 NbO 3 (KNN) [31,32]based materials/composites, afford improved energy storage performance and energy efficiency for energy storage applications. In particular, BT-based ceramics are potential candidates and are widely used for capacitor applications due to their high polarization, high dielectric constant, and low Curie temperature (T C ) [33,34].…”