High-performance 1-3-type composites based on (1-x)Pb(A(1/3)Nb(2/3))O-3-xPbTiO(3) single crystals (A = Mg, Zn)

This paper describes the concentration dependences of piezoelectric coefficients, squared figures of merit and electromechanical coupling factors which have been calculated for 1-3 and 1-0-3 piezo-active composites based on single crystals of relaxor-ferroelectric solid solutions of (1 - x)Pb(A(1/3)Nb(2/3))O3-xPbTiO3 where A = Mg, Zn. The role of the single-crystal component, its electromechanical properties and the polymer matrix (monolithic or porous) in forming these concentration dependences is analysed to demonstrate the ranges in which effective composite parameters are most sensitive to material properties and composite architecture, with particular emphasis on where their maximum values are attained. The basic variables in this study are the chemical composition (x and A), volume concentrations of the single-crystal component, the presence of pores in the polymer matrix and the aspect ratio of the spheroidal pores. It has been shown that particularly high values of piezoelectric coefficient g(33)* similar to 10(2) mV m N-1 and hydrostatic piezoelectric coefficients g(h)* similar to 10(2) mV mN(-1) and d(h)* similar to (10(2)-10(3)) pC N-1 are expected in the 1-0-3 0.67Pb(M1/3Nb2/3)O-3-0.33PbTiO(3) single crystal / porous araldite composite with spheroidal pores in the matrix.