Enwei Sun

Elastic, dielectric, and piezoelectric constants of Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystal poled along [011]c

Ternary single crystals xPb(In1/2Nb1/2)O3–(1−x−y)Pb(Mg1/3Nb2/3)O3–yPbTiO3 (PIN-PMN-PT) poled along [011]c showed remarkable electromechanical properties. We report complete sets of elastic, dielectric, and piezoelectric constants of PIN-PMN-28%PT and PIN-PMN-32%PT, measured by using combined resonance and ultrasonic methods. The electromechanical coupling coefficients k15, k32, and k33 can reach 0.95, 0.90, and 0.92, and the piezoelectric strain coefficients d15, d32, and d33 are as high as 3354 pC/N, −1781 pC/N, and 1363 pC/N, respectively. These full matrix data sets provide the base for fundamental studies on domain engineering phenomena as well as urgently needed input data for the design of electromechanical devices using [011]c poled PIN-PMN-PT single crystals.

Influence of manganese doping to the full tensor properties of 0.24Pb(In1/2Nb1/2)O3-0.47Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystals

Complete sets of elastic, piezoelectric, dielectric, and electromechanical properties of [001]c and [011]c poled pure and 0.5 wt. % manganese-doped 0.24Pb(In1/2Nb1/2)O3-0.47Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystals have been characterized at room temperature. The results indicate that manganese ion substitution in the B-site of perovskite 0.24PIN-0.47PMN-0.29PT single crystals makes the material harder with much higher mechanical quality factor Qm and slight decrease in piezoelectric and dielectric constants. The much improved Qm value (200-900) makes Mn-doped single crystals more suitable for high-power transducer applications than pure single crystals.

Complete set of material properties of single domain 0.24Pb(In1/2Nb1/2)O3-0.49Pb(Mg1/3Nb2/3)O3-0.27PbTiO3 single crystal and the orientation effects

Multidomain relaxor-based single crystals have intrigued the enthusiasm of many researchers due to their superior electromechanical properties. In order to understand the physical origin of multidomain properties, one must know the complete set of material coefficients in single domain state. Previous published single domain data were all measured under bias because single domain state is unstable. Here, we report a set of single domain data without bias for rhombohedral 0.24Pb(In(1∕2)Nb(1∕2))O(3)-0.49Pb(Mg(1∕3)Nb(2∕3))O(3)-0.27PbTiO(3) single crystal. Comparing rotated coefficients from single domain data with measured multidomain material coefficients, we concluded that the orientation effects account for more than 90% of the observed multidomain properties.

Optical interband transitions in relaxor-based ferroelectric 0.93Pb(Zn1∕3Nb2∕3)O3–0.07PbTiO3 single crystal

The optical transmission spectrum of [111]c poled relaxor-based ferroelectric single crystal 0.93Pb(Zn1/3Nb2/3)O3–0.07PbTiO3 (PZN–0.07PT) was measured in the range of ultraviolet to near infrared. The optical absorption edge has been determined and the wavelength dependence of the absorption coefficient was calculated. The direct energy gap Egd=3.144 eV, indirect energy gap Egi=2.915 eV, and phonon energy Ep=0.097 eV (or 782 cm−1) were determined based on the theory of band to band transitions. It was also confirmed by Raman spectra that the indirect transition for the [111]c poled PZN–0.07PT single crystal is mainly due to the contribution of 780 cm−1 phonon corresponding to the Nb–O–Zn bond stretching mode.

Phase coexistence and domain configuration in Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 single crystal revealed by synchrotron-based X-ray diffractive three-dimensional reciprocal space mapping and piezoresponse force microscopy

The crystalline phases and domain configuration in the morphotropic phase boundary composition Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 (PMN-0.34PT) single crystal have been investigated by synchrotron-based X-ray 3D Reciprocal Space Mapping (3D-RSM) and Piezoresponse Force Microscopy. The coexistence of tetragonal (T) and monoclinic MC phases in this PMN-0.34PT single crystal is confirmed. The affiliation of each diffraction spot in the 3D-RSM was identified with the assistance of qualitative simulation. Most importantly, the twinning structure between different domains in such a mixed phase PMN-PT crystal is firmly clarified, and the spatial distribution of different twin domains is demonstrated. In addition, the lattice parameters of T and MC phases in PMN-0.34PT single crystal as well as the tilting angles of crystal lattices caused by the interfacial lattice mismatch are determined.

Linear electro-optic properties of relaxor-based ferroelectric 0.24Pb(In1/2Nb1/2)O3-(0.76 − x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 single crystals

Linear electro-optic properties of 0.24Pb(In1/2Nb1/2)O3-(0.76 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 single crystals, with compositions in the rhombohedral, morphotropic phase boundary (MPB) and tetragonal phases, have been investigated. Very large effective electro-optic coefficient [Formula: see text] (204 pm/V) was observed in a crystal with the MPB composition when it is poled along [001]. The rhombohedral phase (x = 0.27 and 0.30) single crystals poled along [111] direction and tetragonal phase (x = 0.39) single crystal poled along [001] direction are in single domain, and their electro-optic coefficients ([Formula: see text] = 76, 94, and 43 pm/V for the crystals with x = 0.27, 0.30, and 0.39, respectively) were found to be much higher than that of traditional electro-optic single crystal LiNbO3 ([Formula: see text] = 19.9 pm/V). The electro-optic coefficients of the single crystal in the rhombohedral phase have excellent temperature stability in the experimental temperature range of 10-40 °C. The half-wave voltage [Formula: see text] was calculated to be much lower (less than 1000 V) than that of LiNbO3 single crystal (2800 V). These superior properties make the ternary relaxor-PT single crystals very promising for electro-optic modulation applications.

Influence of phase transitions on green fluorescence intensity ratio in Er^3+ doped K_05Na_05NbO_3 ceramic

The fluorescence intensity ratio (FIR) method is a non-contact temperature (T) measurement technique based on thermally coupled levels of rare earth ions in a doped host. Green fluorescence originating from ²H_11/2 and ⁴S_3/2 states of Er³⁺ doped K_0.5Na_0.5NbO₃ (KNN) ceramic are studied in the temperature range of 300 K to 720 K. The fluorescence intensities change dramatically around phase transition points where the crystal symmetry changes, inducing deviation of the FIR from Boltzmanns law. The temperature determined by the FIR method deviates from thermocouple measurements by 7 K at the orthorhombic to tetragonal phase transition (T_O-T) point and 13 K at the Curie point (T_C). This finding gives guidance for developing fluorescent T sensors with ferroelectrics and may also provide a fluorescent method to detect phase transitions in ferroelectric materials.

Contributions of domain wall motion to complex electromechanical coefficients of 0.62Pb(Mg1/3Nb2/3)O3–0.38PbTiO3 crystals

The loss behavior of 0.62Pb(Mg(13)Nb(23))O(3)-0.38PbTiO(3) (PMN-38%PT) ferroelectric single crystal poled along [001](c) was investigated. It was found that the complex electromechanical coefficients and loss factors change dramatically at the coercive field E(c) around 250 Vmm, representing the intrinsic switching barrier. Since the energy loss is related to the domain wall motion, the imaginary parts of the electromechanical coefficients can be used to study the degree of domain wall motions in relaxor-based ferroelectric single crystals. Experimental results indicate that for this system, domain wall motion contributes significantly to the imaginary parts of electromechanical coefficients. In addition, [001](c) poled PMN-38%PT single crystals have much larger mechanical loss factor compared to that of conventional single crystal like LiNbO(3). This phenomenon is proved to be closely related to 90 degrees domain wall motion in this crystal system.

Structural deformation of 0.74Pb(Mg1/3Nb2/3)O3-0.26PbTiO3 single crystal in 1–3 composites due to interface stresses and poling procedure optimization

Interface stresses strongly influence the functional property of 1–3 piezoelectric composites. Using the translucent nature of (1 − x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 single crystals, we have studied stress distributions and domain configuration changes during poling inside the crystal rods by polarizing light microscopy and piezoresponse force microscopy. It was found that the interface stresses due to interaction with polymeric filler led a deformed rhombohedral phase and caused incomplete poling near rod-edges. Compared with “hard” epoxy (Epotek301) filler, “soft” epoxy (Stycast) filler showed weaker impact on the crystals rods and less influence on domain configurations. We also show that high temperature poling (70 °C) can substantially improve the piezoelectric coefficient of composites filled with hard epoxy due to creeping above the glass transition Tg. Analytic stress distribution equations based on cylinder rods were modified to explain the physical principle and to predict the stress distribution for s...

Aging and thermal stability of [001]c- and [111]c-poled 0.63Pb(Mg1/3Nb2/3)O3–0.37PbTiO3 single crystals

The aging characteristics and thermal stability of [001]c- and [111]c-poled tetragonal 0.63Pb(Mg1/3Nb2/3)O3–0.37PbTiO3 single crystals have been studied. For [001]c-poled crystal, the d33,