Phase transition and dielectric properties of (1-x)Pb(Mg_1/2W_1/2)O₃-xPb(Yb_2/3W_1/3)O₃ solid solutions

ABSTRACT

(1-x)Pb(Mg_1/2W_1/2)O₃-xPb(Yb_2/3W_1/3)O₃ ceramics have been prepared by a conventional ceramic process. Their crystal structures, phase transitions and dielectric properties have been investigated in this paper. Limited solid solutions (x ≤ 6 mol%) could be formed. The x = 0.02 composition demonstrates mixture of orthorhombic (Pmcn) and cubic (Fm-3m) phases, while apparent single-phase solid solution with B-site 1:1 ordering (space group: Fm-3m) could be observed for the 0.02 < x ≤ 0.06 compositions at room temperature. The solid solution demonstrates a first-order phase transition. Local orthorhombic distortion in the cubic matrix above transition temperature, manifested in the large temperature factors of Pb²⁺ and O²⁻ observed in the structure refinements, could be further confirmed by Raman analysis. The doping of (Yb_2/3W_1/3)⁴⁺ leads to the decrease in orthorhombic-cubic phase transition temperature. The microscopic nature affecting the driving force of the phase transition was discussed from the point of stereochemistry.

KEYWORDS:

• Double complex perovskite
• phase transition
• dielectric properties
• crystallography

Disclosure statement

No potential conflict of interest was reported by the author(s).