Low temperature sintering and dielectric properties of (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3−xCu2+ ceramics obtained by the sol-gel technique

Abstract

Lead-free Cu 2+-modified (Ba 0.85 Ca 0.15)(Ti 0.9 Zr 0.1)O 3 (BCZT-xCu 2+) piezoelectric ceramics was synthesized by sol-gel method. The effects of Cu 2+ additions on sintering characteristics, the phase structure, microstructure, electrical properties and complex impedance characteristic were investigated systematically. The XRD patterns exhibited a pure perovskite structure without impurity phase in all samples. SEM micrographs, temperature dependence of dielectric constant and polarizationelectric field (P-E) hysteresis loops indicated that a small amount of Cu 2+ addition affected the properties obviously. The results revealed that the addition of Cu 2+ significantly improved the sinterability of BCZT ceramics which resulted in a reduction of sintering temperature from 1440 °C to 1230 °C. The TG-DSC was analyzed to verify the reaction process of BCZT-Cu 2+ materials. (Ba 0.85 Ca 0.15)(Ti 0.9 Zr 0.1)O 3 ceramics with x = 0.020 Cu 2+ exhibited good electrical properties: ε m = 12112, T c = 360 K, ε r = 2614, tan δ = 0.026, K p = 0.47 and d 33 = 382 pC/N. The results indicated that Cu 2+-modified BCZT ceramics could be a promising candidate for commercial purposes.

Thermally-stable high energy storage performances and large electrocaloric effect over a broad temperature span in lead-free BCZT ceramic

“…[14][15][16][17] Moreover, it was reported that BCZT ceramics possess low dielectric loss (tan d) (1-3%), which is encouraging for obtaining high-efficiency energy storage density. 10,[18][19][20][21] BCZT relaxor ferroelectric ceramics have been attracting much attention for energy storage applications and electrocaloric cooling devices owing to their outstanding dielectric and ferroelectric properties. 22,23 Zhan et al 24 achieved an energy storage density of 590 mJ cm À3 and storage efficiency (h) of 72.8% in Ba 0.95 Ca 0.05 Zr 0.30 Ti 0.70 O 3 ceramics at 160 kV cm À1 .…”

Realizing Enhanced Electrical Properties of CaBi2Nb2O9-Based High-Temperature Piezoceramics by Constructing a Pseudophase Boundary

“…Normally, semicircles in high-, middle-, and low-frequency regions represent the contributions from the grain interior, grain boundary, and ceramic−electrode interface, respectively. 14,46 As shown, large semicircles at the high-frequency range can be observed for both the CBN and CBNCC-0.015 ceramics, revealing that the grains dominate the conduction process of both ceramics. It should be noted that a small arc at the low-frequency range can be noticed for the pure CBN ceramic, which is related to the electrode polarization.…”

“…So as to find out the detailed reason for the change in resistivity, the Nyquist plots of the CBN and CBNCC-0.015 samples at various temperatures are given in Figures c and d. Normally, semicircles in high-, middle-, and low-frequency regions represent the contributions from the grain interior, grain boundary, and ceramic–electrode interface, respectively. , As shown, large semicircles at the high-frequency range can be observed for both the CBN and CBNCC-0.015 ceramics, revealing that the grains dominate the conduction process of both ceramics. It should be noted that a small arc at the low-frequency range can be noticed for the pure CBN ceramic, which is related to the electrode polarization. , A series model of two parallel (CQR) elements is selected to fit the Nyquist plots.…”

Structural, dielectric and ferroelectric properties of Cu2+- and Cu2+/Bi3+-doped BCZT lead-free ceramics: a comparative study

“…Such type of behaviour can be attributed to the decrease in grain and grain boundary resistances with increasing temperature (Table 3) as these resistances are related to the diameter of the semicircles. For all samples the grain boundary resistance value is higher compared to grain resistance because the grain boundaries are normally more insulating and capacitive than grains [54]. With the increase in temperature, grain boundary resistance decreases and conductivity increases and can be attributed to the ionisation of oxygen vacancies at high temperatures [55].…”