E-field induced phase transition in ⟨001⟩-oriented rhombohedral 0.92Pb(Zn1/3Nb2/3)O3-0.08PbTiO3 crystals

E-field induced phase transformation and associated changes in dielectric/piezoelectric properties of [001]-oriented rhombohedral 0.92Pb(Zn1/3Nb2/3)O-3-0.08PbTiO(3) crystals were investigated. The longitudinal strain level was found to abruptly increase at 20 kV/ cm, corresponding to that where an induced phase appears within a multidomain matrix. Decreases in the dielectric constant (K-3(T) similar to 4000 to 500), transverse coupling (k(31) similar to 70% to 50%) and transverse piezoelectric coefficient (d(31) similar to -1100 to -200 pC/N) associated with the induced phase were the result of increased crystal anisotropy. By contrast, the thickness coupling (k(T)) increased from 53% at 0 kV/cm to 64% at 45 kV/ cm, associated with this phase transition. The measured dielectric and piezoelectric properties found for the induced phase state were nearly identical to those of [001] poled tetragonal (1-x) PZN-xPT (x > 0.1) crystals. Based on these results, it is evident that the symmetry of induced phase is tetragonal, 4 mm. (C) 1999 American Institute of Physics. [S0021-8979(99)04602-2].