New insights into BaTi_1–x Sn _x O₃ (0 ≤ x ≤ 0.20) phase diagram from neutron diffraction data

Abstract

Neutron powder diffraction (NPD) was employed to further investigate the BaTi1−xSnxO3 (BTS) system previously studied by X‐ray diffraction. The room‐temperature phase compositions and crystal structures of BTS samples with x = 0, 0.025, 0.05, 0.07, 0.10, 0.12, 0.15 and 0.20 were refined by the Rietveld method using NPD data. It is well known that barium titanate powder (x = 0) crystallizes in the tetragonal P4mm space group. The crystal structures of the samples with 0.025 ≤ x ≤ 0.07 were refined as mixtures of P4mm and Amm2 phases; those with x = 0.1 and 0.12 show the coexistence of rhombohedral R3m and cubic phases, while the samples with x = 0.15 and 0.20 crystallize in a single cubic phase. Temperature‐dependent NPD was used to characterize the BaTi0.95Sn0.05O3 sample at 273, 333 and 373 K, and it was found to form single‐phase Amm2, P4mm and structures at these respective temperatures. The NPD results are in agreement with data obtained by differential scanning calorimetry and dielectric permittivity measurements, which show a paraelectric–ferroelectric transition (associated with structural transition) from to P4mm at about 353 K followed by a P4mm to Amm2 phase transition at about 303 K.

Structural perspective on the anomalous weak-field piezoelectric response at the polymorphic phase boundaries of (Ba,Ca)(Ti,M)O3Abebe1, Brajesh2, Mishra3 et al. 2017Phys. Rev. B291180View full textAdd to dashboardCite

“…Qualitatively, this phase diagram is similar to that of BCTS (Fig. 6a), with the three phase boundaries Pm3m-P4mm, P4mm-Amm2 and Amm2-R3m merging at ~ 11 mole percent of Sn at ~ 45 o C. As per this phase diagram, and also reported earlier [20,37,38], the P4mm-Amm2 and Amm2-R3m boundaries at room temperature are at y = 0.05 and y = 0.08, respectively. Amm2 phase is stable in the shown in Fig.…”

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

“…According to Toby [16], the relatively high values of the R-factors can be attributed to the conditions of the data collection such as high counting statistics and background levels. Similar results have been found in similar systems BaTi1-xSnxO3 [17,18]. Indeed, the most important way to determine the quality of a Rietveld fit is to check the observed and calculated patterns graphically and to ensure that the model is chemically plausible [16].…”

Tuning ferroelectricity by manipulating the global and local structure in a lead-free Sr-doped Ba(Ti1-x Snx)O3ceramics

“…These static PNRs have been experimentally confirmed and are believed to be responsible for the diffuse and relaxor phase transitions in this system [29,[38][39][40]. Despite extensive dielectric studies, the structural picture is not yet clear as various contradictory models have been reported for this system [41][42][43].…”