Structural and dielectric properties of iron doped barium strontium titanate for storage applications

Abstract

Barium strontium titanate (BST) and iron doped barium strontium titanate (BSTF) ceramics with general formula (Ba 0.5 Sr 0.5 Ti 1-y Fe y O 3 ) and different iron (Fe) contents were prepared by slow rate injection sol-gel technique. The phase analysis, morphology and dielectric properties of BSTFs were investigated. The phase analysis was carried out using XRD which revealed the crystallization of BSTF in perovskite structure with single phase. The Fe doped BST peaks shifted toward higher angles and the calculated crystallite size was 19 nm on average. The BSTF morphology was studied using TEM which showed that the particle size was affected by Fe content. The average particle size was found to be 37 nm for (Ba 0.5 Sr 0.5 Ti 1-y Fe y O 3 ) with Fe concentration of (y = 0.01, 0.05 and 0.1) calcined at (600, 800 and 1000°C). The dielectric measurements were carried out using impedance analyzer at room temperature as a function of frequency in the range of 10 Hz to 1 MHz. The dielectric constant and dielectric loss of the 1 mol% Fe-doped Ba 0.5 Sr 0.5 TiO 3 at 1 kHz were 1453.69 and 0.0063, respectively. The BSTF ceramics with high dielectric constant and low dielectric loss were obtained for the application DRAM cell capacitor.

Dielectric and structural studies of ferroelectric phase evolution in dipole‐pair substituted barium titanate ceramics

“…Effects of dopants, substitutions, and additives on the electric properties of BT have been investigated to improve the frequency adaptive performance of the material through systematic adjustment of the phase transition temperature, reduction of loss, and reduction in both temperature sensitivity and relative high permittivity while maintaining or increasing the relatively high electricfield tunability over extended temperature ranges. [6][7][8] Some of these property dependencies, for example, in both dissipation factor and temperature sensitivity of the relative permittivity coincide with capacitor requirements for industry [9][10][11][12] and must coexist with high breakdown strength, relatively high permittivity, intrinsic resistor-capacitor (RC) time constant, and cost of the material.…”

Multielement Doped Barium Strontium Titanate Nanomaterials as Capacitors

“…In another observation of Table 1, dielectric properties of the doped BST are afected by variation of sintering and calcination temperatures due to their efect on the number of oxygen vacancies and space charge polarization of the doped BST where increase in sintering temperature mostly resulted in enhanced dielectric constant. Varied relationship of the dielectric loss and sintering temperature has also been observed [73,78]. Calcination temperatures have the capacity to alter particle size of doped BST which further afect the dielectric properties of the doped BST nanomaterial [73].…”

“…(Fe, F)codoped BSTs have shown smaller dielectric constant along with elevated dielectric loss than the Fe-doped BST and pure BST which means that codoping did not improve the dielectric parameters of the unidoped and pure BST. Tis is of course due to the fact that the Fe dopant added on the Ti site caused distortion of the perovskite framework [78,105,130]. In another observation of Table 1, dielectric properties of the doped BST are afected by variation of sintering and calcination temperatures due to their efect on the number of oxygen vacancies and space charge polarization of the doped BST where increase in sintering temperature mostly resulted in enhanced dielectric constant.…”

“…On the other hand, the dielectric loss has shown higher values as calcination temperature was elevated. It was lowered as a result of the elevation of sintering temperature [78].…”

“…Calcination temperatures have the capacity to alter particle size of doped BST which further afect the dielectric properties of the doped BST nanomaterial [73]. Saeed et al reported lowering of dielectric constant as well as elevation of dielectric loss of Fe-doped BST as a result of increment in calcination temperature [78].…”