PMN PT Thick Films Research Articles

Highly Sensitive Surface Acoustic Wave Flexible Strain Sensor

This letter presents a highly sensitive flexible strain sensor based on surface acoustic wave (SAW) working principle. The SAW strain sensor employs the piezoelectric single crystal PMN-PT thick film, which significantly improves the sensitivity of the strain sensor to 1243.49 Hz/ $\mu \varepsilon $ . Meanwhile, the flexible strain sensor fabricated by the chemical and mechanical polishing process can realize a wide strain measurement range from −1000 to $+ 1000\,\,\mu \varepsilon $ . The repeatability of the device is also evaluated under the strain of 0 and $900~\mu \varepsilon $ . The testing results demonstrate that this developed sensor is an excellent candidate for small stain measurement.

Prototyping of a High Frequency Phased Array Ultrasound Transducer on a Piezoelectric Thick Film

A process including virtual prototyping of a high frequency phased array ultrasound transducer on a piezoelectric thick film using a finite element method (FEM) is shown. Generated FEM models were based on PMN-PT (Pb(Mg1/3Nb2/3)O3-PbTiO3) thick films, made by sol-gel technique, with the thickness vibrational mode resonant frequency of each film being close to 28.5MHz. Ultrasound transducers with such characteristics, due to their size and high frequency, are suitable for use in small medical diagnostic tools intended for use in delicate and sensitive areas (for example in ophthalmology and dermatology). With respect to their size, the transducers should retain very good focusing, beam steering and other advantages that phased array layout offers. To ensure an optimal performance of the phased array ultrasound transducer on such a piezoelectric thick film, several electrode patterns were used and tested in FEM simulations with the end goal of getting best performance from the PMN-PT thick films. A 64-element configuration was shown to be a promising technological solution for ophthalmological ultrasound diagnostics.

Development of high performance piezoelectric d33 mode MEMS vibration energy harvester based on PMN-PT single crystal thick film

In this paper, we present the development of the d33 mode piezoelectric MEMS energy harvester, which is made of composite cantilever beams from single crystal PMN-PT thick film, and silicon layer. The PMN-PT piezoelectric thick film is deployed to improve the coupling coefficient and electromechanical coefficient. The d33 mode harvester based on interdigital electrodes contributes to improve its energy conversion efficiency. The hybrid processes composed of wafer bonding and mechanical lapping for thinning is successfully developed to prepare the PMN-PT thick film. The experimental results show that the fabricated prototype excited at 1.5g vibration level can generate a maximum output voltage of 5.36 VP–P and corresponding power of 7.182μW at the resonant frequency of 406.0Hz. The power density is calculated as 17,181.8μWcm−3, which is superior to the devices fabricated by other technologies in the reported literature.

Sol–gel derived PMN–PT thick films for high frequency ultrasound linear array applications

A 12-µm PMN–PT [0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3] thick film was produced by alternate spin-coating of a ceramic powder/sol–gel composite and infiltration of the sol–gel. Using this technique, a high quality PMN–PT thick film was obtained, showing a permittivity εr of ~3300 and dielectric loss factor of ~0.02 at 1 kHz. Photolithographic and wet etching techniques were used to fabricate a 32-element linear array from the film. The completed array showed a center frequency of approximately 110 MHz and a bandwidth of 60% at −6 dB without a matching layer. The performance of the kerfless array was studied and compared to a kerfed array simulated with finite element analysis.

0.65Pb(Mg 1/3Nb 2/3)O 3–0.35PbTiO 3 thick films prepared by electrophoretic deposition from an ethanol-based suspension

We have investigated the processing of 0.65Pb(Mg 1/3Nb 2/3)O 3–0.35PbTiO 3 (denoted PMN–PT) thick films using an electrophoretic deposition process (denoted EPD), with the PMN–PT particles suspended in an ethanol-based suspension. The zeta-potential and the viscosity were measured to identify the conditions for the preparation of a stable suspension suitable for the EPD. The applied voltage, the deposition time, the chemical composition of the suspension and the concentration of the powder were investigated in order to obtain a high-quality PMN–PT deposit with a target thickness of about 50 μm. The PMN–PT thick films prepared from stoichiometric and PbO-excess suspensions by sintering at 950 and 1100 °C were examined by X-ray powder-diffraction analysis and scanning electron microscopy. The highest functional response was obtained for a homogeneous, dense, crack-free PMN–PT thick film prepared from a PMN–PT suspension with excess PbO. The film was deposited at a constant voltage of 10 V and for a time of 120 s, followed by sintering at 1100 °C in a PbO-rich atmosphere. The film's properties were as follows: a dielectric permittivity ɛ of 20,250 at a T m of 172 °C, a remanent polarization of 17 μC/cm 2 and a coercive field of 5 kV/cm.

Relaxor behavior and dielectric properties of lead magnesium niobate–lead titanate thick films prepared by electrophoresis deposition

Lead magnesium niobate–lead titanate (0.80Pb(Mg 1/3Nb 2/3)O 3–0.20PbTiO 3, PMN–PT) thick films on platinum metallic foils were successfully fabricated by electrophoretic deposition (EPD). The room temperature relative dielectric constant and the maximum relative dielectric constant were 4645 and 25,640 at 1 kHz, respectively. The relaxor nature of PMN–PT thick films was studied in terms of diffused phase transition along with frequency dispersion of temperature of dielectric maximum ( T m). Deviation from Curie–Weiss behavior and temperature evolution of the local order parameter were found in the films. The degree of relaxation obtained from the modified Curie–Weiss law strongly suggests the relaxor behavior. Vögel–Fulcher relationship was used to analyze the frequency dependence of temperature of dielectric maximum ( T m).

Preparation and Characterization of Relaxor-Based Ferroelectric Thick Films with Single Perovskite Structure

Lead magnesium niobate-lead titanate (0.8Pb(Mg1/3Nb2/3)O3-0.2PbTiO3, PMN-PT) thick films in the thickness range about 75 μm have been successfully fabricated on Au-coated Al2O3 substrates by electrophoretic deposition (EPD). Non-aqueous colloidal suspensions suitable for EPD were prepared by mixing ultrasonically PMN-PT particles in ethanol with pH=6.0. The effect of EPD process parameters such as deposition voltage, deposition time and the specific deposition mass of PMN-PT particles were investigated. The EPD parameters were optimized in order to obtain crack-free, high-quality uniform ceramic films. The deposited pyrochlore-free PMN-PT thick films were sintered at 1000oC for 30 min, and the phase evolvement and the microstructure of the film were characterized by X-ray diffraction and scanning electron microscope.

STUDY OF PMN-PT THICK FILMS FABRICATED BY SPIN-COATING

Having high dielectric constants and large mechanical strain, relaxor materials are attractive to the application of actuators in electromechanical systems and elements for large and bright display of optical image where the lower operation voltage and larger deformation are required. In this paper, we study the dielectric properties of 0.9PMN-0.1PT thick films fabricated by a spin coating method. The thick film is prepared for the application of large and bright display elements of an optical-image. In this application a layer of PMN-PT is filled in a mold. The thickness of the layer in the device should be in tens or hundreds of micrometers. Therefore, we used spin-coading technique to make PMN-PT thick films. The thickness of the films fabricated with this method ranges from 70mm to 100mm which are suitable to this application. The samples were electroded with silver print and characterized by dielectric constant and loss measurements. The experimental results show that the dielectric loss is less than 2 percent and the dielectric constant is greater than 10 at the room temperature in the frequency ranging from 100Hz to 1.0 MHz. A comparison of the results with those of PZT thick films manufactured with the same method is also presented.