Evidence of short-range antiferroelectric local states in lanthanum- and titanium-modified Sr0.3Ba0.7Nb2O6 ferroelectric ceramics

Abstract

Structural and electrical measurements were performed on lanthanum- and titanium-modified Sr0.3Ba0.7Nb2O6 ferroelectric (FE) ceramics. Dielectric properties show a well-defined relaxor anomaly around -50 degreesC with double-loop hysteresis curves from this point to the transition temperature. The thesis of short-range antiferroelectric (AFE) local states having incommensurate (INC) structure embedded in the FE polar matrix is proposed to explain the observed behavior. Structural lattice parameters show negative expansion coefficients and INC superlattice diffraction spots were observed through the selected-area diffraction patterns in the [110] zone for this minority local states. The titanium modification of this system seems to be the key fact in the coupling of the INC structure to the AFE local states in the FE-AFE coexistence region. (C) 2003 American Institute of Physics.