Temperature-induced phase transitions and structural features of non-polar phases stabilizing below T_C in the PbZrO₃–LaMg_2/3Nb_1/3O₃ system

Abstract

Lead zirconate-lanthanum magnesium niobate (Pb_(1-x)La_х[Zr_(1-x)Mg_2х/3Nb_х/3]O₃) solid solutions with x up to 10 mol.% have been obtained by solid phase synthesis method. It has been found that solid solutions with up to ∼6.0 ÷ 7.0 at.% La³⁺ have the rhombic structure of lead zirconate at the room temperature, but at 0.01 ≤ х ≤ 0.04, it is preceded by an intermediate antiferroelectric phase. It is structurally similar to those found previously in the lead zirconate-stannate system and in lead hafnate. At large values of x, the superstructure is lost in nonpolar phases and the long-wavelength modulation becomes incommensurate.

Keywords:

• Antiferroelectrics
• phase transitions
• incommensurate modulation
• X-ray diffraction
• Raman spectroscopy