The characterrization of high temperature solution-grown crystals of Pb(Fe_1/2^Nb_1/2)O₃

Abstract

Polarization microscope studies on single crystal samples of pb(Fe_1/2 ^Nb _1/2)o₃ [PFN] have been made. Thin platelets (<60μ) show large, homogeneous ferroelectric domains and optical characterization shows PFN is trigonal at room temperature and optically negative. Birefringence measurements between 4.2k and 400k reveal the transition to the cubic structure takes place at 383k, in accordance with earlier work, but they also locate a previously undetected structural modification at 354K, accompanied simultaneously by a re-orientation of the index ellipsoid; both transitions manifest themselves by endothermic reactions on heating in DTA experiments. The new phase is very likely monoclinic.