Dielectric Characteristics of Perovskite‐Structured High‐Temperature Relaxor Ferroelectrics: The BiScO₃–Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ Ternary System

Abstract

A new compositional family of relaxor ferroelectrics was investigated based on the high‐temperature Bi(Me)O3–PbTiO3 ferroelectric perovskite family. Compositions were fabricated near an estimated morphotropic phase boundary (MPB) of the xBiScO3–yPb(Mg1/3Nb2/3)O3–zPbTiO3 (xBS–yPMN–zPT) ternary system exhibiting high‐temperature relaxor properties of Tmax∼250°–350°C and ɛmax∼10 000–24 000 at 1 kHz. Analysis of the low‐field a.c. permittivity by a Vogel–Fulcher type dependence enabled key parameters of activation energy, EA, and freezing temperature, Tf, to be determined. The remanent polarization was studied over a broad temperature range and was observed to show classical ferroelectric square loop hysteresis behavior at temperatures T<Tf while slim loop hysteresis behavior was observed at temperatures Tf<T<Tmax. Pyroelectric current measurements were made and integrated to determine macroscopic polarization‐temperature dependence, and were in excellent agreement with the hysteresis data. The macroscopic polarization was found to drop off rapidly near the freezing temperature, Tf. At temperatures T>Tmax, the deviation temperature, TD, was obtained from Curie–Weiss analysis and found to be ∼600°C. A comparison of characteristic electrical properties was made between the high‐temperature perovskite relaxors and the classical complex lead relaxor compound, Pb(Mg1/3Nb2/3)O3 (PMN).

Microstructure and electrical properties of Aurivillius phase (CaBi2Nb2O9)1−x(BaBi2Nb2O9)x solid solution

“…18 But traditional RFE piezoelectrics, such as Pb͑Mg 1/3 Nb 2/3 ͒O 3 -PbTiO 3 and Pb͑Zn 1/3 Nb 2/3 ͒O 3 -PbTiO 3 , are not suitable for application under harsh thermal conditions due to their relatively low T m temperatures ͑Ͻ300°C͒, at which there is the maximum of dielectric permittivity. 19,20 There are relatively few reports on relaxor behavior in BLSFs solid solution ceramics. we reported that CBNO has the highest-known Curie point ͑943°C͒ among BLSFs and the highest thermal depoling temperature for polycrystalline ferroelectric ceramics.…”

Сегнетоэлектрические релаксорные свойства образцов системы (1-2x)BiScO-=SUB=-3-=/SUB=-&#183; xPbTiO-=SUB=-3-=/SUB=-&#183; xPbMg-=SUB=-1/3-=/SUB=-Nb-=SUB=-2/3-=/SUB=-O-=SUB=-3-=/SUB=- (0.30&le; x&le;0.46)

“…Керамика твердых растворов (1 − x)BiScO 3 · xPbTiO 3 (BS−PT) со структурой перовскита с составами близкими к морфотропной фазовой границе (МФГ) между их ромбоэдрической и тетрагональной фаза-ми (x = 0.64), характеризуется пьезомодулями d 33 ∼ ∼ 400 pC/N [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], сопоставимыми по величине с пьезо-модулями цирконата-титаната свинца (ЦTС) -широко используемой пьезокерамики [17][18][19]. При этом точка Кюри керамики BS−PT (T c ∼ 720 K) превышает T c ЦТС на ∼ 100 K, что позволяет повысить температурный диапазон ее использования.…”

High temperature lead-free relaxor ferroelectric: Intergrowth Aurivillius phase BaBi2Nb2O9–Bi4Ti3O12 ceramics

“…1,2 Relaxor ferroelectrics ͑RFE͒ have large dielectric permittivity and electromechanical constants, 3,4 which make them very attractive for the above applications. 5,6 RFE exhibit a broad frequency dependent dielectric anomaly. With increasing frequency, the temperature ͑T m ͒ of the maximum of dielectric permittivity ͑ r max ͒ increases and the magnitude of r max decreases.…”

“…3 However, their relatively low T m temperature may limit their application in high temperature fields. 5,6 Consequently, a great deal of effort has recently been put into exploring new RFE materials with higher T m value. [5][6][7][8][9][10][11][12] RFE exist in the different crystal structures that host ferroelectricity, including perovskites, tungsten bronzes, rutile structure, and Aurivillius phase.…”

“…5,6 Consequently, a great deal of effort has recently been put into exploring new RFE materials with higher T m value. [5][6][7][8][9][10][11][12] RFE exist in the different crystal structures that host ferroelectricity, including perovskites, tungsten bronzes, rutile structure, and Aurivillius phase. 7,8 In perovskites, RFE behavior occurs predominantly in lead-based complex compositions with the general formula Pb͑B 1 B 2 ͒O 3 , ͑B 1 =Mg 2+ ,Zn 2+ ,Ni 2+ ,Sc 3+ ..., B 2 =Nb 5+ ,Ta 5+ ,W 6+ ...͒ or lanthanum-substituted PbZr 1−x Ti x O 3 ͑PLZT͒.…”