Optical Study of PbZrO3and NaNbO3Single Crystals

Abstract

The twinning of the antiferroelectric crystals PbZr${\mathrm{O}}_3$ and NaNb${\mathrm{O}}_3$ has been studied. Essential differences between this twinning and the domain structure of ferroelectric BaTi${\mathrm{O}}_3$ have been observed. It is shown that both orthorhombic PbZr${\mathrm{O}}_3$ and NaNb${\mathrm{O}}_3$ are optically negative and the refractive index is smallest along the $a$ axis, along which axis the main antiparallel ion shifts have been reported. The birefringence of the crystals has been measured as a function of the temperature up to the transition points, and compared with the temperature dependence of the spontaneous strain.