Properties Of Piezoelectric Crystals Research Articles

Advanced Piezoelectric Crystals for Acoustoelectronics

Ferroelectric crystals of LiNb(1-x)TaxO3 solid solutions and piezoelectric crystals Ca3TaGa3Si2O14 were grown by the Czochralski method. The composition of LiNb(1-x)TaxO3 crystals was studied by mass spectrometry with inductively coupled plasma. The piezoelectric properties of crystals were studied and the independent piezoelectric moduli dij were measured. Piezoelectric and acoustic properties of the crystals were studied by the method of high resolution X-ray diffraction and scanning electron microscopy. The temperature dependences of acoustic properties of crystals were investigated.

The performance enhancement and temperature dependence of piezoelectric properties for Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal by alternating current polarization

The comparison and analysis of piezoelectric properties for [001]-oriented PMN-0.30PT by different polarization conditions were investigated. It should be noticed that the average piezoelectric coefficients d33 of PMN-0.30PT crystals were 1860 pC/N by alternating current (AC) polarization and 1380 pC/N by direct current (DC) polarization, which indicates a promotion of 35.3%. The domain patterns in the [001] surface of PMN-0.30PT single crystals under different polarization conditions are obtained by piezo-response force microscopy. The enhancement of piezoelectric performance by AC polarization is attributed to the regular stripe domains with high domain wall density. With the temperature increased to TR-T, both the values of dielectric constant εrT and piezoelectric coefficients d33 under AC polarization condition maintain higher compared to traditional DC poled samples. In addition, both the values of e33 and ε33S under AC polarization retain higher than that of DC polarization, suggesting that the special domain structure with high domain wall density by AC polarization keeps a stable state as the temperature increased to TR-T. When the temperature increased from TR-T to TT-C, the piezoelectric properties of crystals (εrT and d33) under different polarization conditions become the same status, which indicates that the domain structure under the different conditions of polarization may tend to the similar state and the extrinsic contribution from the domain wall motion by AC polarization is disappeared.

On questionable ferroelectric and piezoelectric properties in single crystals

In this short review, a critical analysis of the purported ferroelectric and piezoelectric properties of crystals which have been published is critiqued.

A method to classify piezoelectric crystals

The properties of piezoelectric crystals used as the active elements in many ultrasonic transducers vary among the suppliers even if the crystals are claimed to be in the same category (say Navy I). A method of classifying the piezoelectric crystals is introduced. With this method, one can judge how similar to each other two types of crystals are by taking the crystal parameters as inputs. The parameters of a crystal include its density, velocity, mechanical Q, dissipation, frequency constants, piezoelectric constants, elastic constants, etc. They are transformed into the values around 1 to weaken the dominance of large parameter values. The transformed data form two attribute lists whose cross‐correlation indicates their similarity. If two crystals are similar, their normalized cross‐correlation coefficient is close to 1. Otherwise, it is close to 0. Based on this method, the available piezoelectric crystals can be further classified into different groups.

Precise and cheap experimental setup for fast measurements of piezoelectric properties of crystals

A series impedance method [Mason and Fair, Proc. IRE, 464 (1942); IEEE Standard on Piezoelectricity ANSI/IEEE Std 176-1987 (New York: The Institute of Electrical and Electronics Engeneers, 1987)] is the most popular way for investigation of piezoelectric properties of crystals. The AC voltage generated by a vibrating crystal achieves its maximum if a frequency of an exciting signal applied to the sample is equal to a resonance frequency of the sample. In this article a very simple experimental setup for piezoelectric measurements was described. Usually measurements of resonance frequencies are made at a constant temperature, which makes an experiment long-lasting. The experimental setup described below allows performance of the experiment in slow-change temperature regime.

The Effective Elastic Constants of Porous Polycrystals of Trigonal Symmetry

A theory behind the effective properties of piezoelectric crystals is considered. It is based on the stochastic electroelastic equations of a microinhomogeneous medium. The initial equations are reduced to integral equations, which, after conditional averaging, are reduced to a system of linear algebraic equations in component-average parameters. The effective electroelastic properties of porous polycrystals with trigonal symmetry are evaluated

Investigation of piezoelectric properties of crystals using surface excitation of ultrasonic waves and some results for ferroelectric triglycine sulphate

The surface excitation of ultrasonic waves as a new method of investigation of piezoelectric properties of materials is suggested and experimental results specified to theZ-direction of a single crystal of triglycine sulphate (TGS) are reported. It has been found that the piezoelectric stress constant e23 of TGS depends on temperatureθ as:e23=K23(θc−θ)−1 whereK23=(31±0.5) As m−2 deg andθc=49.6°C.

Piezoelectric transducer materials

Properties of piezoelectric crystals and ceramics are reviewed as they affect use of such materials in electroacoustic transducers. Extensive data on lead titanate-zirconate ceramics are presented to help in selection of the appropriate material for a variety of applications in the lower and medium frequency range, up to several megacycles per second. Quartz and several recently discovered piezoelectric crystals will share the higher megacycle range.