Effect of grain size on the electrical properties of (Ba,Ca)(Zr,Ti)O3 relaxor ferroelectric ceramics

Abstract

͑Ba 0.90 Ca 0.10 ͒͑Zr 0.25 Ti 0.75 ͒O 3 (BCZT) relaxor ferroelectric ceramics with grain sizes of 0.85, 2.5, 15, and 30 m were prepared from powders synthesized using a sol-gel process. The effects of grain size and dc field on the dielectric properties and tunabilities of BCZT ceramics were investigated. As the grain size decreased, the maximum dielectric constant decreased and the transition temperature increased. The BCZT ceramics with various grain sizes showed a typical relaxor ferroelectric behavior. The dielectric relaxation rate follows the Vogel-Fulcher relation. The dielectric constant is greatly suppressed and the low loss is obtained under a dc electric field. At room temperature ͑300 K͒ and 20 kV/ cm, the tunabilities and figures of merit are 42% and 62, 51% and 98, 56% and 193, and 51% and 182, respectively, for the BCZT ceramics with grain sizes of 0.85, 2.5, 15, and 30 m.

Tuning of dielectric, pyroelectric and ferroelectric properties of 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 ceramic by internal clamping

“…In addition, a parameter ∆T 1 (∆T 1 = T m − T VF ) is also listed in table Table III, to compare the relative freezing temperatures for all samples. 80 For pure and glass added BNT-BT-ST ceramics, ∆T 1 also increases. It suggests that the relaxor behaviors in these systems are analogous to that of a dipolar glass with polarization fluctuations above a freezing temperature.…”

“…The relaxor behavior can be induced by several means such as microscopic composition fluctuation, the merging of micropolar regions into macropolar regions, or a coupling of order parameter and local disorder mode through the local strain. 78,80 Additionally, it was observed that temperature also affects domain growth and domain wall motion in ferroelectric ceramics. It is reported in literature that as the temperature increases coercive field, P s and P r decreases.…”

“…However, relaxor ferroelectric materials exhibit diffuse phase transition of dielectric permittivity. Under this circumstance, modified Curie-Weiss law is used which can be expressed as: 77,80 …”

“…Therefore, Debye equation cannot be employed to obtain a best fit. In order to analyze the relaxation features, the relaxation rate (ω) corresponding to freezing of relaxation time spectrum is described by the Volgel-Fulcher relation as: 78,80 …”

Continuous BaTi1−yZryO3 (0≤y≤1) nanocrystals synthesis in supercritical fluids for nanostructured lead-free ferroelectric ceramics

“…In literature, such effect on the relaxor behaviour is mainly reported in lead based compounds. Regarding the lead free nanostructured ceramics, this was mainly discussed in the BCTZ case [28][29][30][31]. Such lack in the materials property understanding must be filled out to develop the nanosized components required for a higher degree of integration in electronic devices.…”