Portal de Periódicos da CAPES

Dielectric Characteristics of Perovskite‐Structured High‐Temperature Relaxor Ferroelectrics: The BiScO 3 –Pb(Mg 1/3 Nb 2/3 )O 3 –PbTiO 3 Ternary System

2008; Wiley; Volume: 91; Issue: 6 Linguagem: Inglês

10.1111/j.1551-2916.2008.02298.x

1551-2916

Craig J. Stringer, Niall J. Donnelly, Thomas R. Shrout, Clive A. Randall, Edward F. Alberta, Wesley S. Hackenberger,

Microwave Dielectric Ceramics Synthesis

A new compositional family of relaxor ferroelectrics was investigated based on the high‐temperature Bi(Me)O 3 –PbTiO 3 ferroelectric perovskite family. Compositions were fabricated near an estimated morphotropic phase boundary (MPB) of the x BiScO 3 – y Pb(Mg 1/3 Nb 2/3 )O 3 – z PbTiO 3 ( x BS– y PMN– z PT) ternary system exhibiting high‐temperature relaxor properties of T max ∼250°–350°C and ɛ max ∼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, E A , and freezing temperature, T f , 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 < T f while slim loop hysteresis behavior was observed at temperatures T f < T < T max . 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, T f . At temperatures T>T max , the deviation temperature, T D , 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(Mg 1/3 Nb 2/3 )O 3 (PMN).