Peculiarities of surface acoustic waves,propagation in structures with functionally graded piezoelectric materials,coating from different ceramics on the basis of PZT

A model of a piezoelectric structure with an inhomogeneous coating is considered.The structure is a homogeneous half-space made of PZT-5H ferroelectric ceramics with a functionally graded coating.The properties of coating vary continuously in thickness from parameters of one material to parameters of another material in a continuously nonmonotonic or piecewise-continuous manner.As coating materials,various combinations of ceramics of different stiffness based on PZT are considered.Using the example of the problem of the propagation of sh-waves in a piezoelectric structure,we studied the influence of the ratio of the physical parameters of the coating materials,the localization region,and the size of the transition zone of one material to another on the propagation features of surface acoustic waves(SAWs)and the structure of the wave field.

Specific features of SH-waves propagation in structures with prestressed inhomogeneous coating made of piezoceramics based on LiNbO_(3)

Within the framework of the linearized theory of electroelastic wave propagation,a model of a piezoelectric structure with a prestressed functionally graded coating made of piezoceramics of a trigonal system with a symmetry class of 3m is considered.The ferroelectric LiNbO_(3) is used as the main material of the structure.The initial deformed state of the coating material is homogeneous,induced by the action of initial mechanical stresses and an external electrostatic field,the properties of the coating continuously change in thickness.By the example of the problem of the propagation of SH-waves from a remote source for structures with an inhomogeneous prestressed coating in the case of an electrically free and short-circuited surface,the influence of the nature and localization of the inhomogeneity of the coating on the features of SAW propagation is studied.The separate and combined effects of initial actions on changes in the physical properties of the structure,the transformation of the surface wave field,and the change in the SAW velocities in a wide frequency range is studied.The results obtained in this work are useful for understanding the dynamic processes in prestressed piezoelectric structures,in the optimization and design of new structures and devices on SAW with high performance characteristics.

Structure,microstructure,dielectric and piezoelectric properties of(1−x-y)BiFeO_(3)-xPbFe_(0.5)Nb_(0.5)O_(3)-yPbTiO_(3)ceramics

Ceramics of quasi-binary concentration section(x=0.50,0.1≤y≤0.2,Δy=0.025)of the ternary solid solution system(1−x−y)BiFeO_(3)-xPbFe_(0.5)Nb_(0.5)O_(3)-yPbTiO_(3)were prepared by the conventional solid-phase reaction method.By using X-ray diffraction technique,the phase diagram of the system was constructed,which was shown to contain the regions of cubic and tetragonal symmetry and the morphotropic phase boundary between them.Grain morphology,dielectric and piezoelectric proper­ties of the selected solid solutions were investigated.The highest piezoelectric coefficient d_(33)=260 pC/N was obtained.Dielectric characteristics of ceramics revealed ferroelectric relaxor behavior,a region of diffuse phase transition from the paraelectric to ferroelectric phase in the temperature range of 350-500 K.

Impact of laser pulse repetition frequency on nucleation and growth of LiNbO_(3)thin films

This paper reports the impact of the laser pulse repetition frequency on growth processes,morphological and electro-physical parameters of nanocrystalline LiNbO_(3)thin films obtained by the pulsed laser deposition technique.It was found that the nucleation process in LiNbO_(3)films could controllably change by increasing the laser pulse repetition frequency.The film obtained at the repetition frequency of 4 Hz consists of local islands and clusters with a diameter of 118.1±5.9 nm.Nanocrystalline films,grown at the repetition frequency of 10 Hz,possess a continuous granular structure with a grain diameter of 235±11.75 nm.Achieved results can be used for the development of promising“green”energy devices based on lead-free piezoelectric energy harvesters.

Applied theory of bending vibration of the piezoelectric and piezomagnetic bimorph

Based on the variational principle,equations and boundary conditions for transverse steady vibrations of a bimorph consisting of a piezoelectric and piezomagnetic layers are obtained.The results of calculations of natural frequencies are compared with the finite element model of the device in ACELAN.