Growth and ferroelectric/piezoelectric properties of (K,Na)(Nb,Ta)O_3 ferroelectric single crystals

摘要

Single crystals of (K,Na)Nb_(1-x)Ta_xO_3 (KNNT) were grown by the top-seeded solution growth (TSSG) method under high oxygen pressure atmosphere (P_(O_2) = 0.9 MPa), and their dielectric properties were investigated along [100]_(cubic) (the cubic notation). KNNT single crystals in a composition range of 0 ≤ x ≤ 0.65 were successfully obtained. Through the measurements of x-ray diffraction and dielectric properties, we propose a temperature (T)-composition (x) phase diagram in the KNNT system in which a successive phase transition from orthorhombic (Amm2), tetragonal(P4mm) to cubic (Pm 3 m) occurs with increases in T and x.