Articles techniques et présentations

Outline of presentation: theory of phase-field modeling of ferroelectric materials parameter identification in free energy density finite element implementation: PDE form weak form periodic boundary conditions: electrical mechanical domain configurations intrinsic and extrinsic ... En savoir plus

Ferroelectric technology continues to attract significant interest due to its wide range of applications (capacitors, nonvolatile memories, accelerometers ...). In this work we present a finite element model of a ferroelectric. Piezoelectric and ferroelectric matrix are included. The ... En savoir plus

The dielectric properties of ferroelectric PVDF polymer embedded core-shell (Al-Al2o3) nanoparticle is simulated using COMSOL Multiphysics® software. Significant increase in electrical permittivity of the composite at percolation threshold (K = 2800) is achieved when compared to ... En savoir plus

A novel type of tunable surface acoustic waves (SAW) filter based on 1D phononic crystal controlled by electric is field proposed. The tunability of proposed filter varied over a wide range: 1-20%. Basic idea is electrical controlled induced periodical domains in ferroelectric film based ... En savoir plus

We theoretically studied the microwave coplanar line of different geometry based on MgO substrate with a thin (30 nm) ferroelectric layer under the external electric field using the environment of 3D modeling in COMSOL Multiphysics®, RF Module, Frequency Domain. Frequency dependence of ... En savoir plus

A series of ferroelectric ceramic models with grain and grain-boundary structures of different sizes are established via Voronoi tessellations. The relation between the electric displacement and electric field and the hysteresis loop are calculated using a finite element method based on ... En savoir plus

Large strain is crucial for piezoelectric ceramics to be used as actuators. In this work, a piezoelectric composite with core-shell structure is proposed to pursue high strain at a low applied electric field. The core of the piezoelectric composite is typical ferroelectric material, ... En savoir plus

Finite Element analysis is used to model 2-D and 3-D paraelectric-dielectric composites (BaTiO3 spherical fillers randomly distributed in constant dielectric matrix). The effective dielectric response and tunability are studied under different filler sizes and different volume fractions. ... En savoir plus

氧化铪基铁电薄膜材料是一种新型的铁电材料，可以与先进的CMOS工艺兼容；同时其膜厚低于10nm以下时，仍具有良好的铁电性。氧化铪基铁电材料的铁电畴变属于一级相变，因此，与传统铁电薄膜材料中铁电相连续分布的状态相区别的是，氧化铪基铁电薄膜中往往铁电相与非铁电相共存。氧化铪基铁电薄膜材料存在的“唤醒”效应和疲劳失效等问题，本质是由于薄膜内部可翻转铁电相随时间增加或者不断减少引起的。铁电畴的产生及畴壁运动是铁电畴翻转的微观决定因素，因此，铁电畴翻转性能本质上是由铁电畴及畴壁的动力学行为所决定的。只有找到了铁电畴畴壁动力学行为的基本规律，才能从根本上实现对铁电畴翻转性能的调控 ... En savoir plus

Finite element modelling of surgical transducers has been performed and is described. Ultrasonic transducers vibrating at around 25 kHz are used in orthopaedic surgery to cut bone. The high acoustic impedance of the metal blades used in these devices couples energy more efficiently to ... En savoir plus