Precipitation hardening in piezoceramics
Final Report Abstract
This project achieved precipitation hardening in barium-based and lithium-niobate based materials based on parameter field variations of processing and specifically aging treatment. Future considerations for suitable material systems need to consider the change of solubility of dopants with temperature with ideally complete solubility at sintering temperature and complete precipitation at aging temperature. In detail, dopant elements can remain in the matrix during precipitation, as long as they do not deteriorate the piezoelectric properties. This is particularly critical in relaxor ferroelectrics. In choosing the composition for precipitation hardening, the crystallography at aging temperature is crucial with a non-cubic precipitate advantageously leading to platelet-like or needle-like morphology. Demonstrated properties of precipitated systems are outstanding with an increase of mechanical quality factor of up to a factor of 8. Also, this particular LNN system was demonstrated to provide excellent high-power stability. The effects of precipitates on functional properties have been demonstrated using in-situ synchrotron diffraction and in-situ transmission electron microscopy. Follow-up work is ongoing in four funded projects at TU Darmstadt (2), Iowa State University and Xi´an Jiaotong University as well with a large German company on technical ceramics.
Publications
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Precipitation Hardening in Ferroelectric Ceramics. Advanced Materials, 33(36).
Zhao, Changhao; Gao, Shuang; Yang, Tiannan; Scherer, Michael; Schultheiß, Jan; Meier, Dennis; Tan, Xiaoli; Kleebe, Hans‐Joachim; Chen, Long‐Qing; Koruza, Jurij & Rödel, Jürgen
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Coherent Precipitates with Strong Domain Wall Pinning in Alkaline Niobate Ferroelectrics. Advanced Materials, 34(38).
Zhao, Changhao; Gao, Shuang; Kleebe, Hans‐Joachim; Tan, Xiaoli; Koruza, Jurij & Rödel, Jürgen
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Extrinsic and intrinsic contributions to the electrostrain in precipitation-hardened barium calcium titanate. Applied Physics Letters, 121(16).
Zhao, Changhao; Zhang, Mao-Hua; Rödel, Jürgen & Koruza, Jurij
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Precipitate-domain wall topologies in hardened Li-doped NaNbO3. Acta Materialia, 254, 118998.
Gao, Shuang; Zhao, Changhao; Bohnen, Matthias; Müller, Ralf; Rödel, Jürgen & Kleebe, Hans-Joachim
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Transitions from soft to hard piezoelectricity of (Ba, Ca)(Ti, Zr)O3 ceramics via precipitation hardening. Applied Physics Letters, 122(13).
Zheng, Mupeng; Zhao, Changhao & Rödel, Jürgen
