Electrocaloric effect and dielectric properties in ferroelectric ceramics based on solid solution of barium-calcium titanate

Abstract

Barium titanate based ceramics is the most common class of lead-free ceramics due to its high values of dielectric constant, polarization, piezo- and electrocaloric effects. In this paper dielectric properties and electrocaloric effect in ceramics based on solid solution of barium-calcium titanate had been studied. It was shown, that increasing of calcium titanate in solid solution leads to increasing of dielectric constant and electrocaloric effect, simultaneouslyit leads to decreasing of leakage currents. While increasing fraction of calcium titanate from 0% to 10%, dielectric constant at frequency of 1 kHz rises from 10500 to 13600, maximum adiabatic electrocaloric response at ΔE = 1.3 V/μm rises from 0.5 K to 0.7 K.

Role of Density and Grain Size on the Electrocaloric Effect in Ba0.90Ca0.10TiO3 Ceramics

“…To compare our results with similar systems reported in the literature, the electrocaloric responsivity (ζ = ΔT/ΔE) was calculated and the results are presented in Figure 7 for all samples. In our case, the maximum of ζ is 0.56 K mm/kV, which is much higher than the 0.49 K mm/kV reported for the same composition by the direct method [ 18 ] and 0.17 K mm/kV for Ba 0.8 Ca 0.2 TiO 3 [ 19 ]. This result is also very good in comparison with another barium titanate solid solution, single or double substituted [ 30 , 31 , 32 ].…”

“…Although some papers were published concerning dielectric and ferroelectric properties of BCT ceramics [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ], only recently have the electrocaloric effect properties of these ceramics been investigated, and mainly for the double substituted BaTiO 3 [ 17 , 18 , 19 ]. The only paper that reported electrocaloric properties in Ca-doped BT is that of AS Anokhin et al [ 18 ]. The authors investigated the EC effect in 10% Ca-doped BaTiO 3 and obtained a maximum of EC at the transition temperature.…”

The Effect of Ca Dopant on the Electrical and Dielectric Properties of BaTi4O9 Sintered Ceramics

“…Ceramics compounds i.e., BaTi 4 O 9 , BaTi 5 O 11 and Ba 2 Ti 9 O 20 , exhibit better relative permittivity values and insignificant dielectric loss in the region radio frequency [ 3 ]. Moreover, a complex perovskite AB 4 O 9 type, i.e., Barium tetra titanate (BT 4 ), where A and B sites usually represent cations and many researchers make additions to these sites, enhances the microwave dielectric properties [ 4 , 5 , 6 , 7 ]. Meanwhile, doping divalent metals (Ca 2+ , Sr 2+ , Sn 2+ ) onto BaTi 4 O 9 improves the dielectric properties (ε r ) of the sample, such as the quality factor (Q) and temperature coefficient of resonant frequency (τ f ), which are important in the manufacture of electronic devices.…”