Lattice Distortion of PbZrO₃

Abstract

A slight orthorhombic distortion of perovskite type crystal lattice of antiferroelectric PbZrO 3 which is very close to tetragonal, was successfully detected by compairing carefully the observed and the calculated X-ray diffraction profiles of the powder diffractometry data. The prototypic cubic perovskite cell changes the shape into monoclinic, a m = c m =4.158, b m =4.110 Å and β=90^°5.6' at room temperature, confirming Shatalova et al .'s result. In contrast to the Shatalova's result, however, the lattice slightly contracts along the direction of antiparallel shift of Pb ions rather than the extension. The true orthorhombic unit cell is a =2 a m cos (β/2), b =4 a m sin (β/2) and c =2 b m .