Growth and Characterization of Lead Zirconate-Titanate (PbZr1-xTixO3)-Based Novel Piezo-/Ferroelectric Single Crystals

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Single Crystals
Donor/Acceptor Doping
Solid Solution

Piezo-/ferroelectric materials form an important class of functional materials that can transduce mechanical energy to electrical energy and vice versa. PbZr1-xTixO3 (PZT) ceramics are the most extensively used piezoelectric materials owing to their good piezoelectric and electromechanical properties near the morphotropic phase boundary (MPB). However, the microstructures of this class of materials and the atomistic phenomena that cause the outstanding performance have not been thoroughly understood yet. Therefore, it is of particular interest to grow single crystals of PZT, which are not only necessary for thorough characterization of the anisotropic properties of this system, but also are expected to exhibit superior piezo-/ferroelectric performance over their ceramic counterparts. In this work, PZT single crystals with compositions of x = 0.54 and 0.45 were grown successfully by a top-seeded solution growth (TSSG) method, and characterized by X-ray diffraction, polarized light microscopy (PLM), piezoresponse force microscopy (PFM), and dielectric, ferroelectric, and piezoelectric measurements. On the other hand, given that PZT ceramics used in industry are always chemically modified to obtain desired and enhanced properties for specific applications, we extended our work to grow donor (La3+ and Bi3+)- and acceptor (Mg2+ and Mn2+)-doped PZT single crystals and to investigate the effects of the doping on the structure and properties. The compositions and homogeneity of the as-grown doped PZT single crystals were investigated by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and energy dispersive spectroscopy (EDS). The dielectric, ferroelectric and piezoelectric properties of these single crystals were investigated. These very first set of data on doped PZT single crystals not only provide a better understanding of structure-property relationship of PZT-based single crystals and their doping mechanisms, but also points to the possible applications of doped PZT single crystals as a new high-TC, high-performance piezo-/ferroelectric material. Moreover, there have been pressing demands for lead-free or lead-reduced replacement materials because of the environment concerns arising from the potential toxicity of the lead in high-performance piezo-/ferroelectric material such as PZT. In our search for high-temperature, lead-reduced piezoelectric materials, novel ferroelectric single crystals of complex perovskite ternary solid solution Bi(Zn0.5Ti0.5)O3-PbZrO3-PbTiO3 (BZT-PZ-PT) have been grown for the first time. The structure and properties of these crytals suggest that the BZT-PZ-PT ternary single crystals constitute a new family of high-TC ferroelectric materials, which are promising for various applications such as high-power electromechanical transducers that can operate in a wide temperature range.

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Zuo-Guang Ye
Science: Department of Chemistry
Thesis type: 
(Thesis) Ph.D.