Structural, dielectric, ferroelectric and tuning properties of Pb-free ferroelectric Ba0.9Sr0.1Ti1-xSnxO3

Abstract

A series of Pb-free ferroelectric materials Ba0.9Sr0.1Ti1-xSnxO3 (BSTS-x) with 0  x  0.15 was successfully prepared via solid-state reaction method. The effect of Sn substitution on the crystal structure, microstructure, dielectric behavior, ferroelectric and tunable features of BSTS-x ceramics were systematically investigated. Room temperature (RT) x-ray diffraction (XRD) analysis using the Rietveld refinement method reveals that all the synthesized BSTS-x ceramics were well crystallized into single perovskite structure. The results show a tetragonal phase for 0.00  x  0.02, which evolves to orthorhombic and tetragonal coexisting phases for 0.05  x  0.07. The composition x = 0.10 showed a mixture of tetragonal, orthorhombic and rhombohedral phases at RT, while a single cubic phase is observed for x = 0.15. The crystal phases determined by XRD were confirmed by Raman spectroscopy. Enhanced dielectric permittivity with a maximum value of ′~ 35000 is observed for x = 0.10 at RT. The ferroelectric behavior of BSTS-x ceramics was investigated through polarization hysteresis loops and tunability measurements. High tunability of 63% at RT and under the low DC-applied electric field of 1.40 kV/cm is achieved for x = 0.10.

Enhanced electrocaloric and energy-storage properties of environment-friendly ferroelectric Ba0.9Sr0.1Ti1−xSnxO3 ceramics

“…As a consequence, the dielectric constant is highly improved. This enhancement was explained by Shi et al for Sn doped BT [39], as discussed in our earlier work [26]. They have noticed that the formed Polar Nano-Regions (PNRs) in the matrix BT under matrix stress, which should have smaller lattice constants due to their lower Sn concentration, expand.…”

“…In our previous paper [26], the results of dielectric measurements showed that with increasing Sncontent in BST lattice, the three transitions merge into one broad peak near RT at x = 0.10, i.e., at the quasi-quadruple point in the phase diagram (inset of Fig. 1).…”

“…Polycrystalline BSTS-x ceramics with nominal compositions x = 0.00, 0.05 and 0.10 were fabricated via the conventional solid-state reaction method using barium carbonate (BaCO3, 99.8%), strontium carbonate (SrCO3, 99.8%), titanium dioxide (TiO2, 99.8%) and stannic dioxide (SnO2, 99.9%) as starting raw materials from Alfa Aesar company. A detailed description of sample preparation and phase diagram can be found elsewhere [26]. Before performing the measurements, silver electrodes were coated on both sides of the ceramic samples.…”

“…Lately, Lu et al [25] reported a large EC effect strength of DTEC/DE = 0.52 K mm/kV at 309 K in Ba1-xSrxSn0.05Ti0.95O3 (x = 0.10) ceramics. In addition, our previous work [26] has demonstrated that the partial substitution of Sn 4+ in Ba0.9Sr0.1TiO3 (BST) lattice (Ba0.9Sr0.1Ti1-xSnxO3, x = 0.00 -0.15) shifted the phase transition to room temperature (RT) and also improved its dielectric and ferroelectric properties. Thus, a part of the present paper focuses on the lead-free ferroelectric Ba0.9Sr0.1Ti1-xSnxO3 (denoted BSTS-x) ceramics as potential candidates for solid-state refrigeration applications.…”

“…Thus, a part of the present paper focuses on the lead-free ferroelectric Ba0.9Sr0.1Ti1-xSnxO3 (denoted BSTS-x) ceramics as potential candidates for solid-state refrigeration applications. It is worth noting that a detailed description of the crystal structure, the microstructure and tuning properties of the BSTS-x samples have been reported elsewhere [26].…”