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 $\text{0.92}{\mathrm{Pb(Zn}}_{\mathrm{1/3}}{\mathrm{Nb}}_{\mathrm{2/3}}{\mathrm{)O}}_{\mathrm{3}}{\mathrm{–0.08PbTiO}}_3$ 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 ${\mathrm{(K}}_3^T$ ∼4000 to 500), transverse coupling ${\mathrm{(k}}_{31}\text{∼70\%}$ to 50%) and transverse piezoelectric coefficient ${\mathrm{(d}}_{31}\text{∼−1100}$ to −200 pC/N) associated with the induced phase were the result of increased crystal anisotropy. By contrast, the thickness coupling ${\mathrm{(k}}_T)$ 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 $\text{(1−x)}\mathrm{PZN}\mathrm{-x}\mathrm{PT}\text{\hspace{0.5em}(x>0.1)}$ crystals. Based on these results, it is evident that the symmetry of induced phase is tetragonal, 4 mm.