Ferroelectric ceramics

About: Ferroelectric ceramics is a research topic. Over the lifetime, 4458 publications have been published within this topic receiving 117294 citations.

Magnetic and electrical properties of single-phase multiferroic BiFeO3

Abstract: We have reported the structural, thermal, microscopic, magnetization, polarization, and dielectric properties of BiFeO3 ceramics synthesized by a rapid liquid-phase sintering technique. Optimum conditions for the synthesis of single-phase BiFeO3 ceramics were obtained. Temperature-dependent magnetization and hysteresis loops indicate antiferromagnetic behavior in BiFeO3 at room temperature. Although saturated ferroelectric hysteresis loops were observed in single-phase BiFeO3 ceramic synthesized at 880 °C, the reduced polarization is found to be due to the high loss and low dielectric permittivity of the ceramic, which is caused by higher leakage current.

Highly Ordered, Millimeter‐Scale, Continuous, Single‐Crystalline Graphene Monolayer Formed on Ru (0001)

Abstract: The ferroelastic phase transition and shape memory effect in La-modified lead zirconate titanate ferroelectric ceramics are demonstrated directly through the temperature-dependent macroscopic recoverable strain measured in a three-point bending configuration. X-ray diffraction measurements reveal that non-180 degrees domain switching occurs in the mechanically poled sample in two different ways at the bottom and top of the sample which have been under tensile and compressive stresses, respectively. The calculated fraction of non-180 degrees switched domains in the poled sample increases nonlinearly with the applied force and shows a saturation trend, which is consistent with the nonlinear behavior of the remnant strain. This study confirms that the mechanical stress applied upon cooling ferroelectric ceramics from the paraelectric to the ferroelectric phase can easily activate ferroelastic domain switching and give rise to preferred domain orientation and consequent macroscopic remnant strain which results in a history effect and shape memory effect via the ferroelastic phase transition.

Stress and frequency dependence of the direct piezoelectric effect in ferroelectric ceramics

Abstract: It is shown that at weak alternating stress the relationship between the piezoelectrically induced charge and applied stress in ferroelectric ceramics has the same form as the Rayleigh law for magnetization versus magnetic field in ferromagnetic materials. Applicability of the Rayleigh law to the piezoelectric effect is demonstrated in detail for lead zirconate titanate (PZT) ceramics. Experimental results indicate that the dominant mechanism responsible for piezoelectric hysteresis and the dependence of the piezoelectric coefficient on the applied ac stress is the pinning of non-180 degrees domain walls. The dependence of the piezoelectric coefficient on the frequency of the driving stress is examined and is shown to be due to the frequency dispersion of both reversible and irreversible components of domain-wall displacement. Analysis of the stress dependence of the piezoelectric phase angle reveals piezoelectric hysteresis contributions that are not necessarily due to Rayleigh-type displacement of domain walls. Piezoelectric properties of a modified lead titanate composition that exhibits non-Rayleigh type behavior are examined and compared with the properties of PZT ceramics. (C) 1997 American Institute of Physics.

Evolving morphotropic phase boundary in lead-free (Bi1/2Na1/2)TiO3–BaTiO3 piezoceramics

Abstract: The correlation between structure and electrical properties of lead-free (1−x)(Bi1/2Na1/2)TiO3–xBaTiO3 (BNT-100xBT) polycrystalline piezoceramics was investigated systematically by in situ synchrotron diffraction technique, combined with electrical property characterization It was found that the morphotropic phase boundary (MPB) between a rhombohedral and a tetragonal phase evolved into a morphotropic phase region with electric field In the unpoled material, the MPB was positioned at the transition from space group R3m to P4mm (BNT-11BT) with optimized permittivity throughout a broad single-phase R3m composition regime Upon poling, a range of compositions from BNT-6BT to BNT-11BT became two-phase mixture, and maximum piezoelectric coefficient was observed in BNT-7BT It was shown that optimized electrical properties are related primarily to the capacity for domain texturing and not to phase coexistence

Flexoelectricity of barium titanate

Abstract: Flexoelectricity was investigated as a function of temperature in paraelectric and ferroelectric phases of barium titanate ceramic. The flexoelectric coefficient μ12 was measured dynamically at small level of strain gradients. μ12 is around 5μC∕m in orthorhombic phase, rises to about 10μC∕m at room temperature, and peaks at ∼50μC∕m near tetragonal-cubic phase transition point. The coupling effect between mechanical strain gradient and electric polarization is found to be nonlinearly enhanced by high dielectric permittivity and domain contribution in barium titanate. In inhomogeneously strained ferroelectrics, mechanical gradient field may impact electric polarization in a way analogous to electric field.