Chemical Synthesis, Sintering and Piezoelectric Properties of Ba_0.85Ca_0.15 Zr_0.1Ti_0.9O₃ Lead‐Free Ceramics

Abstract

The preparation of Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 (BCZT) powders by wet chemical methods has been investigated, and the powders used to explore relationships between the microstructure and piezoelectric properties (d 33 coefficient) of sintered BCZT ceramics. Sol-gel synthesis has been shown to be a successful method for the preparation of BCZT nanopowders with a pure tetragonal perovskite phase structure, specific surface area up to 21.8 m 2 /g and a mean particle size of 48 nm. These powders were suitable for the fabrication of dense BCZT ceramics with fine-grain microstructures. The ceramics with the highest density of 95% theoretical density (TD) and grain size of 1.3 lm were prepared by uniaxial pressing followed by a two-step sintering approach which contributed to the refinement of the BCTZ microstructure. A decrease in the grain size to 0.8-0.9 lm was achieved when samples were prepared using cold isostatic pressing. Using various sintering schedules, BCZT ceramics with broad range of grain sizes (0.8-60.5 lm) were prepared. The highest d 33 = 410.8 AE 13.2 pC/N was exhibited by ceramics prepared from sol-gel powder sintered at 1425°C, with the relative density of 89.6%TD and grain size of 36 lm.

Local piezo-response for lead-free Ba0.9Ca0.1Ti0.9Zr0.1O3 electro-ceramic by switching spectroscopy

“…The poled ceramic shows a bulk d 33 around 232 pC/N. This value is comparable with the bulk d 33 obtained by A. Reyes et al 6 and K. Castkova et al 41 . The local piezo-response and the macroscopic ferroelectric behavior observed in this sample is in agreement with the global tetragonal structure formed, as it can be observed in the XRD 2D-GIXRD and Raman sections.…”

A comparative study of structural and electrical properties in lead-free BCZT ceramics: Influence of the synthesis method

“…3 for multi-component compounds such as BCZT that involves several precursors, this is highly demanding. Nonetheless, synthesis of BCZT using various wet chemical synthesis techniques including Pechini polymeric precursor method and hydrothermal process have been tried in the past [10][11][12][13][14][15][16]. However, neither comparison, nor deep investigation into the grain size effect in both types of ceramics have been undertaken so far.…”

“…It may not be out of place to mention that a few previous reports on comparative studies are available in literature [14,15], which explore relationships between the sintering conditions and only piezoelectric properties of these materials. Present work, on the other hand, provides a comprehensive study correlating the effect of grain size on various other electrical properties as well.…”

Phase transition and improved electrical performance of Ba0.85Ca0.15Zr0.1Ti0.9O3–Ca0.28Ba0.72Nb2O6 ceramics with high Curie temperature

“…This improvement in d 33 and k p could be attributed to the formation of the O-T phase boundary because there are more polarization states involved when near room temperature. In addition, oxygen vacancies should be mainly responsible for the substitution of Nb 5+ ions on the B-site(Ti 4+ )because of the migration of oxygen vacancies, and because of the interaction between defect dipoles and spontaneous polarization inside the domains[26][27][28]. The d 33 and k p values in this study are much higher than those reported for BCZT-xABO 3 ceramics[9- 11], but they did decrease with an increase in CBN content.…”