Effect of shock vector/polarization vector configuration on the generation of ultrahigh voltage by adiabatically compressed ferroelectric materials

2021 ◽  
Vol 119 (9) ◽  
pp. 092903
Author(s):  
Sergey I. Shkuratov ◽  
Jason Baird ◽  
Vladimir G. Antipov
Keyword(s):  
Polarization Vector ◽  
Ferroelectric Materials ◽  
Vector Polarization

The need of electron microscopy in the study of domains and domain walls in ferroelectrics

1994 ◽  
Vol 52 ◽  
pp. 550-551
Author(s):  
Wenwu Cao
Keyword(s):  
Domain Wall ◽  
Domain Walls ◽  
High Mobility ◽  
Continuum Theory ◽  
Polarization Vector ◽  
Ferroelectric Materials ◽  
Dielectric Constants ◽  
Nonlocal Coupling ◽  
Cubic Symmetry ◽  
Gradient Energy

Domain structures play a key role in determining the physical properties of ferroelectric materials. The formation of these ferroelectric domains and domain walls are determined by the intrinsic nonlinearity and the nonlocal coupling of the polarization. Analogous to soliton excitations, domain walls can have high mobility when the domain wall energy is high. The domain wall can be describes by a continuum theory owning to the long range nature of the dipole-dipole interactions in ferroelectrics. The simplest form for the Landau energy is the so called ϕ model which can be used to describe a second order phase transition from a cubic prototype,where Pi (i =1, 2, 3) are the components of polarization vector, α's are the linear and nonlinear dielectric constants. In order to take into account the nonlocal coupling, a gradient energy should be included, for cubic symmetry the gradient energy is given by,

scholarly journals High-order mixed finite elements for an energy-based model of the polarization process in ferroelectric materials

2020 ◽  
pp. 1045389X2095389
Author(s):  
Astrid S Pechstein ◽  
Martin Meindlhumer ◽  
Alexander Humer
Keyword(s):  
Finite Elements ◽  
Remanent Polarization ◽  
Variational Equation ◽  
Mixed Finite Elements ◽  
Polarization Vector ◽  
Internal Variable ◽  
Ferroelectric Materials ◽  
Dissipation Function ◽  
Free Energy Function ◽  
Polarization Process

An energy-based model of the ferroelectric polarization process is presented in the current contribution. In an energy-based setting, dielectric displacement and strain (or displacement) are the primary independent unknowns. As an internal variable, the remanent polarization vector is chosen. The model is then governed by two constitutive functions: the free energy function and the dissipation function. Choices for both functions are given. As the dissipation function for rate-independent response is non-differentiable, it is proposed to regularize the problem. Then, a variational equation can be posed, which is subsequently discretized using conforming finite elements for each quantity. We point out which kind of continuity is needed for each field (displacement, dielectric displacement and remanent polarization) is necessary to obtain a conforming method, and provide corresponding finite elements. The elements are chosen such that Gauss’ law of zero charges is satisfied exactly. The discretized variational equations are solved for all unknowns at once in a single Newton iteration. We present numerical examples gained in the open source software package Netgen/NGSolve.

Inspection and Manipulation of Ferroelectrics on the Nanometer Scale

1999 ◽  
Vol 574 ◽  
Author(s):  
L. M. Eng
Keyword(s):  
Domain Walls ◽  
Near Field ◽  
High Vacuum ◽  
Polarization Vector ◽  
Optical Microscope ◽  
Ferroelectric Materials ◽  
Ultra High Vacuum ◽  
Atomic Scale ◽  
Dynamic Force ◽  
Force Microscopy

AbstractThe increasing interest in scanning probe instruments (SPM) stems from the outstanding possibilities in measuring electric, magnetic, optical, and structural properties of surfaces and surface layers down to the molecular and atomic scale. For the inspection of ferroelectric materials both the scanning force microscope (SFM) and the scanning near-field optical microscope (SNOM) are promising techniques revealing information on the polarization vector and the electric field induced stress within a crystal. Polarization sensitive modes are discussed as is friction force microscopy, dynamic force microscopy (DFM) and voltage modulated SFM. From these measurements, 180° domain walls (c-domains) are resolved down to 4 nm, while 3-dimensional polarization mapping in ferroelectric BaTiO3 ceramics reveals a 25 nm resolution. On the other hand, non-contact DFM measurements in ultra-high vacuum are able to resolve ferroelectric surfaces down to the atomic scale. Then also the chemical heterogeneity at the sample surface is differentiated from ferroelectric domains down to a 5 nm lateral resolution, taking advantage of the short range chemical forces. SNOM in contrast probes the optical properties of ferroelectric crystals both in transmission and reflection. Here image contrast arises from changes in the refractive index between different domains as well as at domain walls. In addition, SPM instruments are used for the local modification of ferroic samples by applying a relatively high voltage pulse to the SPM tip. Domains with diameters down to 30 nm are thus created with the size depending on both the switching and material parameters.

scholarly journals Observation of negative capacitance in antiferroelectric PbZrO3 Films

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Leilei Qiao ◽  
Cheng Song ◽  
Yiming Sun ◽  
Muhammad Umer Fayaz ◽  
Tianqi Lu ◽  
...  
Keyword(s):  
Polarization Vector ◽  
Boltzmann Distribution ◽  
Ferroelectric Materials ◽  
Negative Capacitance ◽  
Capacitance Effect ◽  
External Resistor ◽  
In Series ◽  
The Rich ◽  
Capacitance Effects ◽  
Free Energy Analysis

AbstractNegative capacitance effect in ferroelectric materials provides a solution to the energy dissipation problem induced by Boltzmann distribution of electrons in conventional electronics. Here, we discover that besides ferroelectrics, the antiferroelectrics based on Landau switches also have intrinsic negative capacitance effect. We report both the static and transient negative capacitance effect in antiferroelectric PbZrO3 films and reveal its possible physical origin. The capacitance of the capacitor of the PbZrO3 and paraelectric heterostructure is demonstrated to be larger than that of the isolated paraelectric capacitor at room temperature, indicating the existence of the static negative capacitance. The opposite variation trends of the voltage and charge transients in a circuit of the PbZrO3 capacitor in series with an external resistor demonstrate the existence of transient negative capacitance effect. Strikingly, four negative capacitance effects are observed in the antiferroelectric system during one cycle scan of voltage pulses, different from the ferroelectric counterpart with two negative capacitance effects. The polarization vector mapping, electric field and free energy analysis reveal the rich local regions of negative capacitance effect with the negative dP/dE and (δ2G)⁄(δD2), producing stronger negative capacitance effect. The observation of negative capacitance effect in antiferroelectric films significantly extends the range of its potential application and reduces the power dissipation further.

Multiagent Strategic Interaction Based on a Game Theoretical Approach to Polarization Reversal in Ferroelectric Capacitors

2011 ◽  
Vol 15 (7) ◽  
pp. 806-812
Author(s):  
Dan Ricinschi ◽  
◽  
Eisuke Tokumitsu ◽  
Keyword(s):  
Electric Fields ◽  
Degrees Of Freedom ◽  
Human Subjects ◽  
Applied Mathematics ◽  
Polarization Vector ◽  
Strategic Interaction ◽  
Ferroelectric Materials ◽  
Oxide Material ◽  
New Paradigm ◽  
Ferroelectric Capacitors

Ferroelectric materials are currently integrated in nonvolatile memory devices, whose principle is to allocate 0 and 1 logic bits to opposite orientations of the spontaneous polarization vector that are permitted by crystal symmetry. Typically made of randomly oriented grains, ferroelectrics tend to split into domains, according to the experienced sequence of electric fields, thermal treatments and any structural imperfections. On this background, we attempt to formulate new principles of exploiting such structural and operational degrees of freedom for unconventional applications of ferroelectrics. In this paper, we envision a new paradigm of ferroelectrics as processors of multiagent strategic interactions, employing unconventional mathematical tools (normally used for optimizing the decision-making process of rational human subjects) for analyzing ferroelectric capacitors’ response to combinatorial pulses. Specifically, we quantify the way microscopic assembly laws of the ferroelectric material mediate the amount of polarization reversed by two electrical pulses using the mathematical theory of games, applied to a strategic interaction between two hypothetical players impersonated by the two pulses. Such socially meaningful implementations of applied mathematics concepts onto an oxide material substrate are worth to consider in view of artificial intelligence applications, adding ferroelectrics to the class of media able to perform unconventional computations.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

Investigation of ferroelectrics using conventional and in situ electron microscopy

1994 ◽  
Vol 52 ◽  
pp. 586-587
Author(s):  
V. Saikumar ◽  
H. M. Chan ◽  
M. P. Harmer
Keyword(s):  
Nonvolatile Memory ◽  
Ferroelectric Materials ◽  
Gate Insulator ◽  
Sensors And Actuators ◽  
In Situ Electron Microscopy ◽  
Ferroelectric Domains ◽  
Domain Boundaries ◽  
Domain Interactions ◽  
Memory Applications

In recent years, there has been a growing interest in the application of ferroelectric thin films for nonvolatile memory applications and as a gate insulator in DRAM structures. In addition, bulk ferroelectric materials are also widely used as components in electronic circuits and find numerous applications in sensors and actuators. To a large extent, the performance of ferroelectric materials are governed by the ferroelectric domains (with dimensions in the micron to sub-micron range) and the switching of domains in the presence of an applied field. Conventional TEM studies of ferroelectric domains structures, in conjunction with in-situ studies of the domain interactions can aid in explaining the behavior of ferroelectric materials, while providing some answers to the mechanisms and processes that influence the performance of ferroelectric materials. A few examples from bulk and thin film ferroelectric materials studied using the TEM are discussed below.Figure 1 shows micrographs of ferroelectric domains obtained from undoped and Fe-doped BaTiO3 single crystals. The domain boundaries have been identified as 90° domains with the boundaries parallel to <011>.

Method of first integrals and interface, surface waves

2010 ◽  
Vol 32 (2) ◽  
pp. 107-120
Author(s):  
Pham Chi Vinh ◽  
Trinh Thi Thanh Hue ◽  
Dinh Van Quang ◽  
Nguyen Thi Khanh Linh ◽  
Nguyen Thi Nam
Keyword(s):  
Rayleigh Waves ◽  
Displacement Vector ◽  
Attenuation Factor ◽  
Electrical Potential ◽  
Polarization Vector ◽  
First Integrals ◽  
Dispersion Equations ◽  
Interface Surface ◽  
Electric Induction ◽  
The One

The method of first integrals (MFI) based on the equation of motion for the displacement vector, or  based on the one for the traction vector was introduced  recently in order to find explicit secular equations of Rayleigh waves whose characteristic equations (i.e the equations determining the attenuation factor) are fully quartic or are of higher order (then the classical approach is not applicable). In this paper it is shown that, not only to Rayleigh waves,  the MFI can be applicable also to other waves by running it on the equations for mixed vectors. In particular: (i) By applying the MFI  to the equations for the displacement-traction vector we get the explicit dispersion equations of Stoneley waves in twinned crystals (ii)  Running the MFI on the equations for the traction-electric induction vector and the traction-electrical potential vector provides the explicit dispersion equations of SH-waves in piezoelastic materials. The obtained dispersion equations are identical with the ones previously derived using the method of polarization vector, but the procedure of driving them is more simple.

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