High Piezoelectric Performance in Lead-free BCHT Fine-grained Ceramics Synthesized by Mechanochemistry
Lead-free piezoelectric ceramics (Ba1-xCax) (Ti1-yHfy)O3 with stoichiometries close to the morphotropic phase boundary (MPB) were synthesized by high-energy ball milling. The influence of Hf and Ca contents and the sintering method (conventional and hot-press) on the piezoelectric, dielectric, and f...
| Authors: | , , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2025 |
| Country: | España |
| Institution: | Universidad de Sevilla (US) |
| Repository: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:idus.us.es:11441/174327 |
| Online Access: | https://hdl.handle.net/11441/174327 https://doi.org/10.1016/j.ceramint.2025.04.009 |
| Access Level: | Open access |
| Keyword: | D. BaTiO3 and titanates C. Piezoelectric properties C. Ferroelectric properties C. Dielectric properties |
| Summary: | Lead-free piezoelectric ceramics (Ba1-xCax) (Ti1-yHfy)O3 with stoichiometries close to the morphotropic phase boundary (MPB) were synthesized by high-energy ball milling. The influence of Hf and Ca contents and the sintering method (conventional and hot-press) on the piezoelectric, dielectric, and ferroelectric response was investigated. It was confirmed that the different phases stabilized at room temperature and the structural distortion are strongly dependent on the stoichiometry. The coexistence of tetragonal, orthorhombic and rhombohedral phases was observed in samples with the lowest Ca and Hf contents. These samples, which are in the MPB region, also showed the greatest structural distortion, resulting in higher values of d33. Samples with lower Hf content exhibited a higher coercive field, remnant polarization, and temperature in the ferroelectric to paraelectric transition. Despite the high sintering temperature leading to high densification, grain growth during sintering was limited because of the use of mechanochemically synthesized powders. Although Ba0.85Ca0.15Hf0.10Ti0.90O3 stoichiometry has been reported in the literature as the best for piezoelectric properties, in this work, BCHT solid solution with the lowest dopant content studied (Ba0.90Ca0.10Hf0.05Ti0.95O3) showed the best combination of functional properties. Ceramics of this composition with grain size <2 μm exhibited a d33 > 250 pC/N, with almost no relaxation after 24 h, and the highest permittivity. In the field of piezoelectric materials, there is considerable interest in reducing grain size while maintaining high piezoelectric performance, as this can lead to improvements in mechanical properties. |
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