Phase coexistence and broad depolarization response in (Pb,La)(Zr,Sn,Ti)O3 single crystals

Lead lanthanum zirconate stannate titanate (PLZST) antiferroelectric materials have been intensively studied in the last few decades due to their adjustable phase transition and outstanding performance. Despite the strong interest it has drawn, there is a lack of study of domain structure evolution in antiferroelectric materials with morphotropic phase boundary (MPB) composition, which is of great importance for understanding the phase transition between ferroelectric and antiferroelectric phase. PLZST single crystals with the composition in the MPB region were grown by the flux method in this work. We presented the direct evidence that rhombohedral ferroelectric and tetragonal antiferroelectric phase coexist in the as-grown single crystals. The evolution of phase structure and domain morphology during the temperature-induced phase transition was observed by in situ optical visualization, accompanied by a broadening depolarization response. An enhanced broadening pyroelectric response with a wide temperature window was detected. A modified Ginzburg-Landau-Devonshire theory was employed to elucidate the structural and physical origin of the broadening thermal depolarization. It is anticipated that a further understanding of the phase transition behavior in PLZST single crystals may be helpful in developing novel ferroelectrics and antiferroelectrics with MPB compositions.