G. Yang

Nova Scotia Museum, Halifax, Nova Scotia, Canada

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Publications (17)8.41 Total impact

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    ABSTRACT: Resonance characterisation has been used to determine the variation of the independent piezoelectric, elastic, and dielectric material coefficients, as well as the electromechanical coupling factors, of typical soft and hard lead zirconate titanate (PZT) ceramics as a function of temperature ranging from -165degC to 195degC. The piezoelectric coefficients and the dielectric permittivities generally increased with temperature for both types of PZT whereas the elastic compliance coefficients exhibited broad peaks over parts of the temperature range. Thermal hysteresis was also observed over the temperature cycle.
    Applications of Ferroelectrics, 2007. ISAF 2007. Sixteenth IEEE International Symposium on; 07/2007
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    ABSTRACT: Electric-field-induced phase transitions and piezoelectric properties of <001>-oriented Pb(Mg1/3Nb2/3)O3-32%PbTiO3 (PMN-PT) single crystals have been investigated as a function of temperature. It was found that the phase transitions and piezoelectric properties for PMN-PT crystals are strongly dependent on temperature. The measurements of polarization and longitudinal strain as a function of a unipolar electric field show that the field for the induced monoclinic-tetragonal phase transition decreases linearly with temperature in the range between 23 °C and 75 °C. Raising the temperature can stabilize the tetragonal phase in <001>-oriented PMN-PT crystals. The effective longitudinal piezoelectric constant, d33, in the monoclinic phase increases with temperature. Meanwhile in the field-induced tetragonal phase, d33 is much smaller and has little change with temperature. The electric-field-induced phase transition from a cubic phase to a tetragonal phase was observed at 125 °C.
    Proc SPIE 05/2005;
  • 11th CF/DRDC International Meeting on Naval Applications of Materials Technology, Halifax, Nova Scotia; 01/2005
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    ABSTRACT: Dielectric elastomers are known to produce large transverse strains in response to electrically induced Maxwell stresses and thus provide a useful form of electromechanical actuation. The transverse strain response of silicone (Dow Corning HS III RTV) based Maxwell stress actuators have been measured earlier as a function of driving electric field, frequency and pre-load. Experimental results show that a pre-load initially causes an increase in the strain. However, this increase appears to be a function of the relative geometries of the electroded area and of the specimen itself. The transverse strains in these materials decrease when larger values of pre-load are applied. Models of hyperelasticity that are capable of describing the large deformation of polymer materials have been used to interpret our results. Numerical finite element simulations of the material's behavior using a hyperelastic model provides good agreement with most of our observations on the electric field and pre-strain dependencies of the transverse strain.
    Smart Materials and Structures 01/2005; 5759:134-143. · 2.02 Impact Factor
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    ABSTRACT: Some electroactive polymers show large electric-field-induced strain. However, it is difficult to characterize the transverse strain response, especially the dynamic response, under high driving electric fields. In this work, a transverse strain measurement system based on a ZYGO laser Doppler interferometer has been developed. This system can measure transverse strain responses of polymer actuators of different sizes over a wide displacement and frequency range. By using this system, we have investigated the electric-field-induced strains of electroactive polymer actuators fabricated from silicone (Dow Corning HSIII RTV) films. The static and dynamic strains of the actuators have been measured under various driving electric fields and mechanical loads. Our results show that the polymers exhibit a non-linear relationship between strain and driving field. Mechanical loads have a significant effect on transverse strain responses. Transverse strains of 3.25% (static) and 2.08% (dynamic at 1 Hz) have been obtained under a load-free condition. Our experimental results can be understood on the basis of hyperelastic theory. The actuation of an electroactive polymer actuator is not only determined by its material properties, but also by the actuator structure.
    Applications of Ferroelectrics, 2004. ISAF-04. 2004 14th IEEE International Symposium on; 09/2004
  • G. Yang, W. Ren, J. P. Szabo
    The Eleventh International Congress on Sound and Vibration, St. Petersburg, Russia; 01/2004
  • 7th Cansmart Meeting, International Workshop on Smart Materials and Structures, Montreal, Quebec; 01/2004
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    ABSTRACT: We have investigated the electromechanical response of piezoelectric ceramics as a function of the amplitude and frequency of large electric fields and studied the effects of dc bias fields. In order to characterize the materials under these conditions, a ZMI 2000 laser interferometer system from Zygo Corp. has been installed and modified to directly measure the strains of ferroelectric ceramics. This system uses a heterodyne detection technique and has the advantages of phase detection, wide bandwidth, high stability, and easy optical alignment. Our experiment has been used to determine the strain of lead zirconate titanate (PZT) ceramics as a function of electric fields and as a function of frequency in the low frequency range. From these measurements the piezoelectric coefficients d33, d31, and d15 have been determined as a function of applied field and frequency. In addition the dependence of the piezoelectric coefficients under an applied dc bias field has been studied under quasistatic and under resonance conditions. Some of our measurements have provided evidence of the time dependence of the piezoelectric response. Results on a range of soft and hard PZT ceramics manufactured by EDO Corp. are presented. These results are discussed within the context of extrinsic contributions to the piezoelectric response. © 2003 American Institute of Physics.
    Journal of Applied Physics 07/2003; 94(2):1155-1162. · 2.21 Impact Factor
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    ABSTRACT: Laser Doppler interferometry has been used to determine the strain and piezoelectric response of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) electrostrictive ceramics as a function of electric fields up to 4 MV m-1, frequencies between 0.1 Hz and 2.5 kHz and DC bias fields up to 3 MV m-1. The strain and polarization of PMN-15 with a composition of 0.9PMN-0.1PT and PMN-38 with a composition of 0.85PMN-0.15PT both produced by TRS ceramics, have been measured at room temperature. The strain and polarization responses of PMN-15 ceramics under an electric field up to 4 MV m-1 have been fitted to a polynomial model. The results suggest that a quadratic dependence of strain on polarization is not valid for large electric fields and that higher-order terms must be included. Our measurements showed that the effective piezoelectric coefficient, d33, of PMN-15 ceramics had a maximum value of 800 pm V-1 at a bias field of 0.67 MV m-1 and had little frequency dependence in the frequency range from 1 Hz up to 2.5 kHz. PMN-38 ceramic showed a maximum d33 of 1200 pm V-1 at a bias field of 0.43 MV m-1 and the d33 of this material showed a clear frequency dependence from 1 Hz up to 2.5 kHz.
    Journal of Physics D Applied Physics 06/2002; 35(13):1550. · 2.53 Impact Factor
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    ABSTRACT: Sensors and actuators based on piezoelectric ceramics are finding an increasingly large variety of applications under a very wide range of environmental conditions and applied signals. Some actuator applications require the piezoelectric materials to support large mechanical loads and produce high strain output. In order to accomplish this requirement of higher strains, large electric fields must be applied. This results in a significant non-linear behavior and hence affects the performance of the material. It is therefore important to understand the behavior and properties of these materials over a large range of temperature, frequency and applied electric fields and mechanical stresses. We have measured some of the dielectric, elastic and piezoelectric constants of soft (EC-65, EC-76) and hard (EC-64, EC-69) lead zirconate titanate (PZT) piezoelectric ceramics, manufactured by EDO Ceramics, as a function of temperature, frequency, applied field and applied stress. We have also determined the dependence of the piezoelectric constants on an applied DC bias voltage or stress. The time dependence of the piezoelectric response in the piezoelectric ceramics has also been studied. A summary of the results will be presented. Most of these results can be understood on the basis of the extrinsic contributions to the piezoelectric response that arises from the existence of domains in the material.
    Proc SPIE 07/2001;
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    ABSTRACT: The temperature dependence of the material properties of PMN-PT-La (0.85/0.15/1%) electrostrictive ceramics manufactured by TRS Ceramics Inc. have been investigated. The measurements reported here include: the temperature and frequency dependence of dielectric permittivity and dissipation, the quasi-static strain as a function of applied electric field, and the DC biased resonance characterisation of the dielectric, elastic and electromechanical coefficients at temperatures below, near, and above Tmax.
    Ferroelectrics. 01/2001; 262(1-4):201-206.
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    ABSTRACT: Piezoelectric ceramics are often used under compressive stress. It is therefore important to know the properties of these materials as a function of applied stress. We have developed an experiment that allows us to find the piezoelectric charge coefficient d33, elastic compliance S 33, and dielectric constant ϵ 33 as a function of uniaxial stress in the poled direction. Both dynamic and static measurements can be carried out. The dynamic and static coefficients differ from each other because of the different proportions of reversible and irreversible domain changes that contribute to them and each coefficient can be important in specific applications. Dynamic results for stresses up to 160 MPa on a soft and a hard piezoelectric Lead Zirconate Titanate (PZT) ceramics are presented. The time dependence of the measurement has also been investigated. It was found that the experimental results were strongly dependent on the material type, history of the specimen, stress level, and the time scale of the measurement.
    Ferroelectrics. 01/2001; 262(1-4):207-212.
  • The Journal of the Acoustical Society of America 01/2001; 110(2). · 1.65 Impact Factor
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    ABSTRACT: A laser Doppler interferometer system has been used to measure the strains of ferroelectric ceramics. The strains and polarisation of piezoelectric and electrostrictive ceramics have been investigated as a function of electric fields up to 4 MV/m in the frequency range from 0.01 Hz up to 1 kHz. The field and frequency dependence of the appropriate material constants have been calculated. Results on a range of piezoelectric PZT and electrostrictive PMN-PT ceramic materials are presented.
    Ferroelectrics. 01/2001; 261(1):27-32.
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    ABSTRACT: We have measured some of the dielectric, elastic, and piezoelectric constants of several types of PZT piezoelectric ceramics, manufactured by EDO Corporation, as a function of applied electric field and mechanical stress. Both the high frequency impedance resonance method and the low frequency response of the material under electrical and mechanical excitations were employed to determine these constants. We present the dependence of these material constants on an applied DC bias voltage and on an applied mechanical stress. Most of the results can be understood on the basis of the extrinsic contributions to the piezoelectric response that arises from the existence of domains in the materials
    Ultrasonics Symposium, 2000 IEEE; 11/2000
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    ABSTRACT: A Zygo laser interferometer system has been used to measure the strain induced in piezoelectric lead zirconate titanate (PZT) and electrostrictive lead magnesium niobate (PMN) based ceramics. The piezoelectric coefficients d<sub>33</sub>, d<sub>31</sub> and d<sub>15 </sub> of PZT ceramics have been determined as a function of electric field and frequency. The strain and polarization of PMN-PT ceramics have been measured at AC fields of up to 4 MV/m. For PMN-based ceramics, the results suggest that a quadratic relation of strain with polarization (S=Q·P<sup>2</sup>) is not valid at high electric fields and higher order terms must be considered. DC bias measurements at room temperature showed that the maximum d<sub>33</sub> of PMN-15 ceramics was 800 pm/V at the bias field of 0.67 MV/m and had little frequency dependence in the frequency range from 1 Hz up to 2.5 kHz. However, PMN-38 ceramic, with a maximum d<sub>33</sub> of 1200 pm/V at the bias field of 0.43 MV/m, showed frequency dependence from 1 Hz up to 2.5 kHz
    Applications of Ferroelectrics, 2000. ISAF 2000. Proceedings of the 2000 12th IEEE International Symposium on; 02/2000
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    ABSTRACT: Piezoelectric ceramics are often used under compressive stress. We have measured the dynamic value of the piezoelectric charge coefficient, d<sub>33</sub>, as a function of uniaxial stress in the poled direction. Results on two types of PZT ceramics manufactured by EDO Corporation are presented; in general, they show a nonlinear behaviour with an initial increase in d<sub>33</sub> as the stress increases followed by a significant decrease. The time dependence of the measurement has also been investigated and these studies indicate that the stress induced extrinsic contributions take a finite time to appear and that, over longer time periods, the stress causes ageing
    Applications of Ferroelectrics, 2000. ISAF 2000. Proceedings of the 2000 12th IEEE International Symposium on; 02/2000