| In the recent ten years, the relaxor-normal ferroelectric solid solution single crystals, such as lead zinc niobate-lead titanate (PZN-PT) and lead magnesium niobate-lead titanate (PMN-PT) have attrated a lot of attention for their excellent piezoelectric, electromechanical coupling, optical, acoustic and ferroelectric properties. They can be used as piezoelectric materials for the next generation of ultrasound transducers and high performance micro actuators. The PZN-0.07PT single crystal with composition near the morphotropic phase boundary (MPB) has pure phase structure, high compositional homogeneity, high structural quality, and high macroscopic physical properties. It has been used in making piezoelectric devices. In addition, PZN-0.07PT single crystal can be poled into good single domain state, which has application potential for many optical devices. But up to date, its optical properties have not been reported. Therefore, study the optical properties of PZN-0.07PT single domain single crystal is pratically meaningful. More recently, it has been demonstrated that the lead indium niobate-lead magnesium niobate-lead titanate (PIN-PMN-PT) single crystals have higher coercive field and higher phase transition temperature than the corresponding binary PMN-PT single crystal, which is very important for large field drived piezoelectric devices and has a wider work temperature range. For device applications, it is very important to study the electromechanical propeties of PIN-PMN-PT single crystals.Firstly, the PZN-0.07PT single crystal was poled into single domain state along its spontaneous polarization direction. Then, the refractive indices were measured by using the Brewster angle method. We confirm that the single crystal belongs to positive uniaxial crystal. The linear electro-optic coefficients were measured by a modified Mach-Zehnder interference system. It was found that the effective electro-optic coefficient of PZN-0.07PT single crystal is two times higher than that of the commonly used electro-optic crystal lithium niobate. The influence of inverse piezoelectric effect of ferroelectric crystal on the half-wave voltages of electro-optic phase and intensity modulation systems has been analyzed using the refraction index ellipaoid theory. Based on our results, the inverse piezoelectric effect of ferroelectric single crystal cannot be ignored in electro-optic applications. The transverse piezoelectric strain can greatly reduce the half-wave voltage of electro-optic modulations. The optical absorption edge and inberband energy have been determined by the combined ultraviolet-visible-near infrared absorption spectrum and polarized Raman spectrum. The direct and indirect transitions were analyzed. It was confirmed that the indirect transition is mainly due to the contribution of the phonon corresponding to the Nb-O-Zn bond stretching mode. Our results showed that the PZN-0.07PT single domain single crystal has very high optical transmission, sufficient for many optical devices.The dielectric, piezoelectric, acoustic, and electromachanical coupling properties of new ternary PIN-PMN-PT ferroelectric single crystal have been measured. Several complete sets of full matrix data have been determined under different poling conditions. The [011]c poled PIN-PMN-PT single crystals have excellent shear and transverse piezoelectric properties. The temperature and frequency dependence of dielectric constant have been also determined experimentally. It was demonstrated that the coercive field and phase transition temperatures of PIN-PMN-PT single crystals are much higher than that of binary PMN-PT single crystals. The single domain and orientation properties of PIN-PMN-PT single crystals have been also studied. Our results showed that the orientation effect plays a key role in the macroscopic piezoelectric and electromechanical properties of multidomain relaxor-based ferroelectric single crystals.The frequency dispersion of ultrasonic velocity and attenuation in [001]c poled PIN-0.45PMN-0.31PT multidomain single crystal have been measured by using ultrasonic spectroscopy from 25-100 MHz. Then, the frequency dispersions of real and imaginary parts of the corresponding elastic constant were also determined. The experimental data agree well with the Kramers-Kronig relationship. We found that the attenuation coefficient of the [001]c poled PIN-0.45PMN-0.31PT is only about 40% of that of [001]c poled PMN-0.32PT single crystal, and much lower than the attenuation of PZT piezoelectric ceramics. These results indicate that the ternary relaxor-based ferroelectric PIN-PMN-PT single crystals are very suitable for high frequency medical ultrasound transducers in addition to high power electromechanical devices.
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