Shiyang Li

Orientation dependence of piezoelectric properties and mechanical quality factors of 0.27Pb(In1/2Nb1/2)O3-0.46Pb(Mg1/3Nb2/3)O3-0.27PbTiO3:Mn single crystals

The complete set of material constants of single domain rhombohedral phase 0.27Pb(In1/2Nb1/2)O3-0.46Pb(Mg1/3Nb2/3)O3-0.27PbTiO3:Mn single crystal has been determined. The orientation dependence of piezoelectric, dielectric, and electromechanical properties was calculated based on these single domain data. The maximum piezoelectric and electromechanical properties were found to exist near the [001]C pseudo-cubic direction. In addition, the piezoelectric properties of [001]C poled crystals with “4R” multi-domain configuration were experimentally measured and compared with the calculated values. Only a small difference (3%) was found between experimental and theoretical values, indicating the high piezoelectric properties in the “4R” state are mainly from intrinsic contributions. The mechanical quality factors Q33 are significantly improved by the Mn-doping for the “4R” domain engineered crystals but almost no change for the single domain “1R” state. On the other hand, Q15 of both single domain and multidoma...

Temperature evaluation of traveling-wave ultrasonic motor considering interaction between temperature rise and motor parameters.

In this paper, a novel model for evaluating the temperature of traveling-wave ultrasonic motor (TWUSM) is developed. The proposed model, where the interaction between the temperature rise and motor parameters is considered, differs from the previous reported models with constant parameters. In this model, losses and temperature rises of the motor were evaluated based on the temperature-related varying parameters: the feedback voltage Vaux of the stator, dielectric permittivity ɛ and dielectric loss factor tanδ. At each new temperature, Vaux, ɛ and tanδ were updated. The feasibility and effectiveness of this proposed model was verified by comparing the predicted temperatures with the measured one. The effects of driving voltage, driving frequency and ambient temperature on the predicted temperature were also analyzed. The results show that the proposed model has more accurate predicted temperature than that with constant parameters. This will be very useful for the optimal design, reducing the heat loss, improvement of control and reliability life of TWUSM.

Characterization of full set material constants of piezoelectric materials based on ultrasonic method and inverse impedance spectroscopy using only one sample.

The most difficult task in the characterization of complete set material properties for piezoelectric materials is self-consistency. Because there are many independent elastic, dielectric, and piezoelectric constants, several samples are needed to obtain the full set constants. Property variation from sample to sample often makes the obtained data set lack of self-consistency. Here, we present a method, based on pulse-echo ultrasound and inverse impedance spectroscopy, to precisely determine the full set physical properties of piezoelectric materials using only one small sample, which eliminated the sample to sample variation problem to guarantee self-consistency. The method has been applied to characterize the [001]C poled Mn modified 0.27Pb(In1/2Nb1/2)O3-0.46Pb(Mg1/3Nb2/3)O3-0.27PbTiO3 single crystal and the validity of the measured data is confirmed by a previously established method. For the inverse calculations using impedance spectrum, the stability of reconstructed results is analyzed by fluctuation analysis of input data. In contrast to conventional regression methods, our method here takes the full advantage of both ultrasonic and inverse impedance spectroscopy methods to extract all constants from only one small sample. The method provides a powerful tool for assisting novel piezoelectric materials of small size and for generating needed input data sets for device designs using finite element simulations.

Temperature dependence of dielectric and electromechanical properties of (K,Na)(Nb,Ta)O3 single crystal and corresponding domain structure evolution

Domain structures and their evolution with temperature in the [001] C oriented (K,Na)(Nb,Ta)O3 (KNNT) single crystal have been studied before and after poling by polarizing light microscopy. The results indicate that the KNNT crystal is difficult to be completely poled by the room temperature poling process. The domain structure is rather stable in the orthorhombic phase, but exhibits substantial changes near the phase transition temperatures TO-T and TC. Narrower stripe domains are formed during both the orthorhombic-tetragonal and tetragonal-cubic phase transition processes, no intermediate phases were found during the phase transitions. The temperature dependence of the dielectric and piezoelectric properties were measured, and the influence of domain structures on the dielectric and electromechanical properties were quantified.

A face-shear mode single crystal ultrasonic motor

We report a face-shear mode ultrasonic motor (USM) made of [011]c poled Zt ± 45° cut 0.24Pb(In1/2Nb1/2)O3-0.46Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal, which takes advantage of the extremely large d36 = 2368 pC/N. This motor has a maximum no-load linear velocity of 182.5 mm/s and a maximum output force of 1.03 N under the drive of Vp = 50 V, f = 72 kHz. Compared with the k31 mode USM made of Pb(Zr,Ti)O3 (PZT), our USM has simpler structure, lower driving frequency, much higher electromechanical coupling factor, and twice power density. This USM can be used for low frequency operation as well as cryogenic actuation with a large torque.

Dynamic scaling of internal bias field in Mn-doped 0.24Pb(In 1/2 Nb 1/2 )O 3 –0.42Pb(Mg 1/3 Nb 2/3 )O 3 –0.34PbTiO 3 ferroelectric ceramic

The influences of temperature, electric field, and frequency on the internal bias field Ei have been investigated in poled and aged Mn-doped 0.24Pb(In1/2Nb1/2)O3–0.42Pb(Mg1/3Nb2/3)O3–0.34PbTiO3 ferroelectric ceramic. It was found that Ei decreases with temperature T and electric field amplitude E0, but increases with frequency f. The relaxation behavior of the internal bias field is related to the redistribution of preferentially oriented defect dipoles. Based on our results, scaling relations of Ei on temperature, electric field, and frequency were established in both rhombohedral and tetragonal phases, which provide the foundation for making “harder” piezoelectric materials through point defect engineering in order to meet the demand of high-power piezoelectric device applications.

Temperature dependence of full matrix material constants of [001]c poled 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystal

Up to date, there are no self-consistent full matrix data in the literature on the temperature dependence of material constants for [001]c poled (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) single crystals because it is very challenging to measure such data for low Q-value ferroelectric materials. We report here a combined characterization method to resolve this issue using two samples. The temperature dependence of full set material constants of [001]c poled PMN-0.29PT single crystal was measured from 20 °C to 60 °C. The thickness shear mode sample was used for measuring the material constants having low sensitivity to the resonance spectroscopy method. Another thickness extensional mode sample was used for the determination of the remaining constants. Such temperature dependence of full matrix data would make accurate simulation designs and performance predictions of single crystal devices a reality, which is critically important because sample temperature will increase during the operation. This method may ...

Temperature dependent piezoelectric anisotropy in tetragonal 0.63Pb(Mg1/3Nb2/3)-0.37PbTiO3 single crystal

In this work, we studied the temperature-dependent effective piezoelectric coefficient d 33 * along the arbitrary direction of a tetragonal 0.63Pb(Mg1/3Nb2/3)-0.37PbTiO3 single crystal. Results show that the crystal changes from a rotator ferroelectrics with the maximum d 33 * occurring along the nonpolar direction to a extender type with maximum piezoelectricity along [001]C. Two polymorphic phase transitions, orthorhombic-tetragonal and tetragonal-cubic, greatly influence the PS dynamics, leading to the change of d 33 * anisotropy with temperature. The [011]C oriented crystals possess both improved piezoelectricity and high thermal stability, hence are the best choice for practical applications.In this work, we studied the temperature-dependent effective piezoelectric coefficient d 33 * along the arbitrary direction of a tetragonal 0.63Pb(Mg1/3Nb2/3)-0.37PbTiO3 single crystal. Results show that the crystal changes from a rotator ferroelectrics with the maximum d 33 * occurring along the nonpolar direction to a extender type with maximum piezoelectricity along [001]C. Two polymorphic phase transitions, orthorhombic-tetragonal and tetragonal-cubic, greatly influence the PS dynamics, leading to the change of d 33 * anisotropy with temperature. The [011]C oriented crystals possess both improved piezoelectricity and high thermal stability, hence are the best choice for practical applications.

An improved frequency tracking strategy in ultrasonic transducer

The realization of automatic frequency tracking is of great significance in ultrasonic transducer due to its wide application area in nowadays industrial manufacture. However, excessive overshoot current, serious overheating and long response time remain the urgent issue. To tackle these existing ultrasonic frequency tracking problem, this paper proposes a hybrid technique that integrates fuzzy control theory with PID control on the system. The technique involves coarse adjustment by fuzzy control and accurate adjustment by PID. Then, direct digital synthesizer (DDS) is used to generate required PWM wave with high accuracy. Initial driving frequency of the system and its corresponding phase difference of the feedback voltage and current can both be acquired during sweep frequency test before the tracking process, which corresponds to the parallel resonant point where the current is the minimum. This phase difference is also regarded as the target tracking value. During the tracking process, fuzzy control will be adopted when phase difference value error between feedback value and target value is greater than 10%, or PID will be used. Current difference AI and change rate AI/Af are used as two input values while driving frequency is the output value in fuzzy control when coarse adjustment is needed. Incremental PID arithmetic is used when accurate adjustment is needed. The result shows that the technique can reduce overshoot current of the ultrasonic transducer by approximately 8%, shorten the time for achieving stabilization of the system by 12%. In conclusion, this novel hybrid technique can quickly and stably track the frequency of parallel resonant point of the ultrasonic transducer system, meanwhile keep the whole system operating more efficiency and stable.

An ultrasonic contact-type position restoration mechanism.

An ultrasonic contact-type position restoration mechanism is proposed and investigated in this paper. In the mechanism, two driving points of an ultrasonic vibrator, excited by an AC voltage, produces a restoring force on a slider so that the slider can be pushed back to its equilibrium after it is perturbed away from its equilibrium. The restoring force is generated by the unbalance of ultrasonic frictional driving forces on the slider, which is caused by a pressure difference on the two driving points. A prototype of this mechanism is fabricated, and the effects of the driving voltage, preload between the slider and vibrator, and sliders size on the restoring characteristics are experimentally measured and analyzed.