Refining the phase diagram of Pb1−xLax(Zr0.9Ti0.1)1−x/4O3 ceramics by structural, dielectric, and anelastic spectroscopy investigations

Abstract

We present the results of dielectric and anelastic spectroscopy measurements, together with X-ray diffraction investigations, which allow us to establish more precisely the phase diagram of Pb1−xLax(Zr0.9Ti0.1)1−x/4O3 (PLZT x/90/10) in the compositional range around the AFE/FE phase boundary (0 < x < 0.04). From structural analysis and polarization-electric field measurements, we have found that the ground state of PLZT samples with x < 0.025 is rhombohedral R3c, while samples with x > 0.032 are antiferroelectric with orthorhombic Pbam structure. In-between, for compositions with 0.025 ≤ x ≤ 0.032, a coexistence of the AFE/FE phases is evidenced. The use of complementary dielectric and anelastic techniques allows to follow the phase transitions shifts throughout all the interesting composition range and to construct the temperature-composition phase diagram. The tilt instability line, separating the R3c and R3m low and high temperature phases, has been evidenced. Moreover, the new transition, associated with the onset of disordered tilting preceding the long range order of the R3c phase, previously found in Zr-rich Pb(Zr,Ti)O3, is confirmed in rhombohedral PLZT x/90/10 compositions.

Antiferroelectric to Ferroelectric Crossover and Energy Storage Properties of (Pb1−xLax)(Zr0.90Ti0.10)1−x/4O3 (0.02 ≤ x ≤ 0.04) Ceramics

“…Despite earlier discovery of the AFE/FE phase boundary in Pb 1− x La x (Zr 0.9 Ti 0.1 ) 1− x /4 O 3 (PLZT x /90/10), the energy storage properties across the border have not been adequately addressed . By replacing La 3+ (from 2 to 4 at.%) for A‐site perovskite PLZT x /90/10 ferroelectric material, the properties of ferroelectrics PLZT x /90/10 can be modified, and the AFE orthorhombic phase gradually increases at the expenses of the FE rhombohedral one, whereas PLZT x /90/10 undergoes a FE rhombohedral and AFE orthorhombic transformation . A coexistence of AFE and FE phases in PLZT x /90/10 ceramics with La compositions close to FE to AFE boundary has been previously reported .…”

Field-induced antiferroelectric to ferroelectric transitions in (Pb1–xLax)(Zr0.90Ti0.10)1–x/4O3 investigated by in situ X-ray diffraction

“…[24][25] Since the Pbam ground state is close in energy to a rhombohedral R3c phase, 33 The initially single 200pc reflection develops a distinct shoulder on the lower 2 side (Fig. 2(d)).…”

“…[15][16][17] The AFE-to-FE phase transition is a complex phenomenon, which includes structural phase transformations, unit cell volume changes, domain switching and texture formation. 5,[13][14][15][16][18][19][20][21][22] The AFE-to-FE transition has been reported using macroscopic studies, 12,[23][24][25] however microscopic studies to date are scarce. 5,[13][14][15][16][18][19][20][21][22] There is much that can be learned from studying the structural evolution at various fields before, during and after the AFE-to-FE phase transition.…”

“…AFE lead lanthanum zirconate titanate (Pb1-xLax)(Zr0.90Ti0.10)1-x/4O3 (PLZT x/90/10) ceramics have received increasing interest due to their composition dependent phase boundary region between rhombohedral and orthorhombic phases. 10,[24][25][26]28 Due to the proximity of the FE/AFE phase boundary at 2 x 4 at % of La, a structural transition from orthorhombic Pbam to rhombohedral R3c is expected in AFE PLZT x/90/10 compositions during the application of adequate EAFE-FE threshold (15 EAFE-FE 75 kV/cm) electric field. 10 The aim of this work is to study the structural evolution of the AFE, and field-induced FE phase using in situ X-ray diffraction (XRD) measurements.…”

Raman spectroscopy investigation on (Pb1La )(Zr0.90Ti0.10)1−/4O3 ceramic system

“…This composition, which is in a ferroelectric state at room temperature under atmospheric pressure, can be transformed into the antiferroelectric phase by the application of a hydrostatic pressure or by increasing the temperature [11]. More recently, a new phase diagram has been established for PLZT x/90/10 [12]. It has been reported that below 0.025 at% of lanthanum, there is a FE phase; above 0.032 at% there is an AFE phase; and for 0.025<x<0.032, a coexistence of the AFE/FE phases is evidenced.…”