On the origin of grain size effects in Ba(Ti0.96Sn0.04)O3 perovskite ceramics

Abstract

The study of grain size effects in ferroelectric ceramics has attracted great research interest over the last 50 years. Although different theoretical models have been proposed to account for the variation in structure and properties with grain size, the underlying mechanisms are still under debate, creating a significant level of uncertainty in the field. Here, we report the results of a study on the influence of grain size on the structural and physical properties of Ba(Ti0.96Sn0.04)O3, which represents a model perovskite system, where the effects of point defects, stoichiometry imbalance and phase transitions are minimized by Sn substitution. It was found that different microscopic mechanisms are responsible for the various grain size dependences observed. In fine-grained ceramics, high permittivity is due to high domain wall density and polar nanoregions; high d33 in coarse-grained ceramics results from a high degree of domain alignment during poling; large electric field-induced strain in intermediate-grained ceramics is an outcome of a favourable interplay between constraints from grain boundaries and reversible reorientation of non-180º domains and polar nanoregions. These paradigms can be regarded as general guidelines for the optimization of specific properties through grain size control. I.

A Study on the Relationship Between Grain Size and Electrical Properties in (K,Na)NbO3‐Based Lead‐Free Piezoelectric Ceramics

“…This phenomenon is in agreement with previous report that the R-T phase boundary can greatly enhance the piezoelectricity in KNN-based ceramics. [31,32] These grain-size-dependent features are considered to be responsible for the increased piezoelectricity in poled samples with larger grains due to the enhancement of domain alignment after the poling process. Thus, we can conclude that the critical grain size (approximately 1 µm) has a profound influence on both phase structure and electrical properties.…”

“…Furthermore, the values of E c increase before the grain size approaches 0.5 µm and then decrease slowly with the increase of grain size. The decreased E c is also likely ascribed to the easier domain switching in the samples with coarse grains . These grain‐size‐dependent features are considered to be responsible for the increased piezoelectricity in poled samples with larger grains due to the enhancement of domain alignment after the poling process.…”

Nano-domains in lead-free piezoceramics: a review

“…an R-T phase coexistence. 54,70,130,431 With an increasing AGS, d33 of both ceramics increased monotonously; d33* of BTS0.04 ceramics first increased and then reduced; d33* of B0.85C0.15T0.1Z0.9 ceramics increased monotonously. For BTS0.04 ceramics, it was believed that the high εr achieved in fine-grained BTS ceramics was due to the high domain wall density and PNRs; high d33 was obtained in coarse-grained ceramics due to a high degree of domain alignment during poling; large electric fieldinduced strain in intermediate-grained ceramics was an outcome of a favorable interplay between constraints from grain boundaries and reversible reorientation of non-180° domains and polar nanoregions.…”

Terahertz Probing Irreversible Phase Transitions Related to Polar Clusters in Bi0.5Na0.5TiO3‐Based Ferroelectric

“…This can be explained by the field‐induced transitions that take place at 1 kV, resulting in the enhanced ε′ and ε″ due to the intrinsically induced polarization. When the voltage returns to zero, ε′ and ε″ increase again because the dipoles are no longer locked by the bias field (freezing effect) and respond easily to the AC THz beam field 21. After the application of the −1 kV voltage, the values of both ε′ and ε″ are slightly increased, when compared with those after poling at 1 kV.…”