Phase transition sequence in sodium bismuth titanate observed using high-resolution x-ray diffraction

Abstract

Mn doping-induced structural and magnetic transformations in the antiferroelectric phase of the Bi1−xNdxFeO3 perovskites J. Appl. Phys. 112, 064105 (2012) Neutron diffraction study of stability and phase transitions in Cu-Sn-In alloys as alternative Pb-free solders J. Appl. Phys. 112, 053520 (2012) Communication: From graphite to diamond: Reaction pathways of the phase transition High resolution powder x-ray diffraction patterns of Na 0.5 Bi 0.5 TiO 3 at selected temperatures were examined to compare structural changes with observed piezoelectric thermal depoling temperatures. The depoling temperatures do not correlate with discrete phase transition temperatures, and therefore, a structural transition is not the origin of thermal depoling. Rather, a correlation is made with an increase in volume fraction of material which does not obey the long-range Cc space group. The origin of the thermal depoling behavior may be the loss of long-range ferroelectric order by a decreasing proportion of the Cc phase or the associated percolation of disordered nano-scale platelets.

Structure and properties of Fe-modified Na0.5Bi0.5TiO3at ambient

“…11 A small inclusion of this secondary phase (2 wt%) in unmodified NBT was also observed at room temperature. 11 It may represent the previously reported nano-scale platelets of space group P4bm within the room temperature structure. 8,9 When measured using longer-range probes such as X-ray diffraction, these fractions of the material may result in broadening of the diffraction peaks, as observed in the present work (cf.…”

“…Raman spectroscopy is sensitive to the short-range crystalline order, which below proposed by Dorcet et al 4 We have previously observed similar changes with temperature in unmodified NBT. 11 In this prior work, the thermal depolarization of this material was correlated with an increase in the volume fraction of material which does not correlate with the long-range Cc space group. 11 A small inclusion of this secondary phase (2 wt%) in unmodified NBT was also observed at room temperature.…”

“…11 In this prior work, the thermal depolarization of this material was correlated with an increase in the volume fraction of material which does not correlate with the long-range Cc space group. 11 A small inclusion of this secondary phase (2 wt%) in unmodified NBT was also observed at room temperature. 11 It may represent the previously reported nano-scale platelets of space group P4bm within the room temperature structure.…”

“…4 Recent work from Aksel et al presented in situ high resolution X-ray diffraction measurements of NBT during heating and attributed the depolarization process to an increase in volume fraction of material which is only present at a short range. 11 The T d of NBT may be modified through the addition of dopants or through the use of solid solution alloying with other perovskite structures. For example, Watanabe et al presented the impact of several lanthanide dopants substituted on the perovskite A-site of NBT and found that the T d of NBT decreased with increased dopant content.…”

A family of oxide ion conductors based on the ferroelectric perovskite Na0.5Bi0.5TiO3

“…Mg-doping on the Ti-site increases the ionic conductivity to ~ 0.01 S cm -1 at 600 o C, improves the electrolyte stability in reducing atmospheres and lowers the sintering temperature. This study not only demonstrates how to adjust the nominal NBT composition for dielectric-based applications, but also, more importantly, gives [10][11][12][13][14][15] . NBT exhibits maximum relative permittivity,  r ~ 3000 at ~ 320 o C (T max ) and possesses a distorted perovskite structure with extensive chemical, cationdisplacement and octahedral tilt disorder.…”