Effects of Ca²⁺substitution on dielectric properties of (Ba_0.7Sr_0.3)(Ti_0.9Zr_0.1)O₃ceramics

Abstract

We investigated the dielectric properties of (Ba 0.7 Sr 0.3%x Ca x )(Ti 0.9 Zr 0.1 )O 3 (BSCTZ) and (Ba 0.7%y Ca y Sr 0.3 )(Ti 0.9 Zr 0.1 )O 3 (BCSTZ) (0 ³ x; y ³ 0:2) ceramics sintered at 1550 °C for 6 h. With increasing Ca 2+ ions substitution for Sr 2+ and/or Ba 2+ ions, both of the ceramics showed the decreasing unit cell volume due to the smaller ionic size of Ca 2+ ion than Ba 2+ and/or Sr 2+ ion. Also, BSCTZ and BCSTZ ceramics were found to have perovskite structures with tetragonal (P4mm) and cubic (Pm 3m) symmetry at room temperature. The dielectric constant (ε r ) and breakdown voltage of BSCTZ and/or BCSTZ ceramics depended on the average B-site bond valence. The dielectric loss (tan δ) of BSCTZ ceramics significantly increased with Ca 2+ ions substitution due to the decrease in grain size, whereas that of BCSTZ ceramics decreased only slightly because of the increase in the cubic phase fraction. Finally, we discuss the dependence of the dielectric properties on the crystal structure characteristics of the BSCTZ and BCSTZ ceramics.

Crystal Structural Characteristics and Electrical Properties of (Ba0.7Sr0.3-xCax)(Ti0.9Zr0.1)O3 Ceramics Prepared Using the Citrate Gelation Method

“…For the BSTZ ceramic (x = 0.00), abn grain growth with {111} twins (dark region) was detected, which is a similar result previous studies [23,24]. For all specimens, the average grain size was significantly sm than that of the BSCTZ specimen prepared using the SSR method [17]. The average size of the BSTZ ceramic (x = 0.00) was 1.243 µm, while the BSCTZ ceramic (x = The SEM images of the BSCTZ ceramics are shown in Figure 4.…”

“…In particular, the BDV value (=6.6839 kV/mm) of the x = 0.05 specimen prepared using the CG method was three times higher than that (=2.0043 kV/mm) of the x = 0.05 specimen prepared by the SSR method. This high value can be attributed to the characteristics of the CG method, which induces nucleation during powder production in the liquid phase, resulting in smaller grain sizes and a higher number of grain boundaries than those prepared through the SSR method [17]. those prepared using the SSR method.…”

“…For the (Ba 0.7 Sr 0.3-x Ca x )(Ti 0.9 Zr 0.1 )O 3 (BSCTZ) (0 ≤ x ≤ 0.2) ceramics prepared using the SSR method, a high sintering temperature (1550 • C) and a low breakdown voltage (BDV; ~2 kV/mm) were reported [17]. Thus, the CG method was applied for the synthesis of BSCTZ ceramics in this study to achieve a low sintering temperature and increase the BDV.…”

Effects of sintering temperature on the properties of Mn/Y codoped Ba0.67Sr0.33TiO3 ceramics for tunable application

“…displacement, which increases the polar axis length of the Ti 4? ion [17]. These phenomena enhanced the dielectric constant of the ceramic samples with larger grain size.…”

Dependence of dielectric properties on microstructural characteristics of (Ba0.7Sr0.25Ca0.05)(Ti0.9Zr0.1)O3 ceramics

“…In our previous report [26], the dielectric constant (ε r ) of (Ba 0.7 Sr 0.3 )(Ti 0.9 Zr 0.1 )O 3 ceramics could be improved from 12,000 to 18,000 by 0.05 mole of Ca 2 þ substituted for Sr 2 þ , however, the breakdown voltage (V b ) of the doped specimens showed the low value of about 2 kV/mm, which is the critical disadvantage for high-energy components. Therefore, the dielectric properties especially V b of (Ba 0.7 Sr 0.25 Ca 0.05 )(Ti 0.9 Zr 0.1 )O 3 (BSCTZ) ceramics should be improved with the control of the microstructural characteristics by ZnO addition and/or two-step sintering.…”