Degradation of asymmetrical Pt/SRO/PLZT/Pt capacitors: Role of Pt and oxide electrodes

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Gas evolution in classical alkaline water electrolysers strongly influences electrochemical performance through bubble accumulation at electrode surfaces and within electrolyte channels. Multiphysics modelling using COMSOL software is employed to systematically investigate gas bubble behaviour in both classical finite-gap and zero-gap alkaline water electrolyser configurations. The effects on gas bubble formation of key cell design parameters, including electrode height, as well as operating conditions, suc

The three-level neutral point clamped (3L-NPC) converter is a widely adopted topology in the mediumvoltage (MV) industry. For the megawatt-level direct current transformer (DCT) concept employing integrated gate-commutated thyristor (IGCT) devices and resonant conversion principles, employing the NPC topology with the two-level and three-level operation flexibility is a straightforward and beneficial choice. However, the NPC topology itself may not guarantee the dynamic voltage balancing of synchronously sw

Employing the three-level neutral point clamped (3L-NPC) topology for the LLC resonant DC-DC converter and utilizing the integrated gate commutated thyristor (IGCT) has enabled realization of a MW-level direct current transformer (DCT). Due to the use of three-level modulation only for soft-start and current limiting and two-level modulation in normal operation, design of static and dynamic voltage balancing snubbers is not trivial. While snubber capacitors in parallel with each IGCT ensure dynamic voltage

This paper presents a noise reduction technique for Terahertz imaging based on modulating the THz source in order to transpose the signal at the output of the rectifier at a higher frequency where there is no 1/f noise and then filtering with a high Q bandpass filter centred at the modulation frequency. The filtering circuit, based on a 16-path passive switched capacitor (SC) bandpass filter, is modeled analytically. The presented technique is implemented in a test chip with a 130 nm process. Measurement re

Head-to-head and tail-to-tail 180 degrees domain walls in a finite isolated ferroelectric sample are theoretically studied using Landau theory. The full set of equations, suitable for numerical calculations, is developed. The explicit expressions for the polarization profile across the walls are derived for several limiting cases and wall widths are estimated. It is shown analytically that different regimes of screening and different dependences for the width of charged domain walls on the temperature and p

We formulate an approach to the size effect problem in ferroelectric-electrode systems where ab initio calculations are combined with a phenomenological framework. The parameters of the model can be extracted from the calculations, while experimentally verifiable predictions can be made on thick films. We illustrate this approach by applying it to SrRuO3/BaTiO3/SrRuO3 heterostructures with different terminations of the metal-oxide electrodes.

The phenomenon of polarization imprint consisting of the development of a preferential polarization state in ferroelectric films is known as one of the major issues impacting the development of high density ferroelectric memories. According to the commonly accepted scenario, the imprint is related to the charge injection and charge accumulation in the nearby-electrode passive layer of the ferroelectric film. Recent studies demonstrated that the coercive voltage shift induced by the imprint exhibits a nonlin

The analysis of the dynamic behavior of power transmission line and telecommunication towers is of interest in protection and EMC studies related to lightning. Usually, time-domain surge impedance is used to characterize tower dynamic behavior. The main drawback in the definition of such surge impedance is that it is dependent on the excitation waveshape and there is no consensus on the current waveshape to be used. Also, there is no consensus on the unique definition of the involved voltage. This paper exp

Relaxor ferroelectric thin films exhibit a drastic reduction in the dielectric constant and associated properties in the thin film form, even for thicknesses in the micron range, which are essentially infinity for the size effects typically investigated in conventional ferroelectrics. In order to investigate this phenomenon, the material system Lead Scandium Tantalum (PST) was fabricated by a Sol-Gel technique using mixed acetate and alkoxide precursors. The positional order of the "B" site species was tail

In current tokamaks and, in particular, in future larger devices such as ITER, the control of neo-classical tearing modes (NTM) is essential for achieving high performance in terms of the beta limit. A commonly used scheme for NTM stabilization consists in driving a helical current at the resonance surface of interest with electron-cyclotron-current-drive. Depending on the ratio between the magnetic island size and the RF beam width, complete stabilization of the NTM will only be achieved with deep RF power

NOVELTY - A micro-electro-mechanical-system (MEMS) is manufactured by the use of a sacrificial layer that is made of silicon. USE - The invention is used in surface micromachining for the manufacture of a MEMS containing a suspended metal layer or MEMS device architecture. MEMS device is a suspended gate metal oxide semiconductor field effect transistor (SG-MOSFET). It is used as radio-frequency capacitive switch, current switch, radio-frequency tuneable capacitor, magnetic field sensor, accelerometer, and

The present study aims at a better understanding of the high piezoelectric properties encountered in lead-based ferroelectrics by focusing on the extrinsic contributions to the response. The main characteristics of these materials are the highly nonlinear character of the electro-mechanical response and the presence of a morphotropic phase boundary (MPB) where properties are reaching a maximum. Thus, our approach was first to develop a new description for the piezoelectric hysteresis and nonlinearities and

Dielectric breakdown of (Pb,La)(Zr,Ti)O-3(PLZT) film capacitors with Pt and SrRuO3 electrodes, in its initial or virgin state and after voltage cycling that causes polarization fatigue, is studied by constant-current measurements. It is shown that for different types of PLZT capacitors, the breakdown onset is controlled by the critical charge flown through the film (charge to breakdown) rather than the voltage applied to the capacitor. The charge to breakdown for the asymmetrical Pt/SrRuO3/PLZT/Pt capacitor

The domain nucleation and growth during polarization switching in Pb(Zr,Ti)O-3 (PZT) ferroelectric thin film capacitors with Pt top (TE) and bottom electrodes (BE) were studied by means of atomic force microscopy (AFM). The experimental configuration used in this study differs from that conventionally used (AFM tip/PZT/BE) where the AFM tip acts as a positionable TE. A small ac voltage was applied between the electrodes with a step by step increasing dc bias voltage. The induced piezoelectric vibration was

Recent publications on so called multilevel inverters deal with series connected cells, mainly developed for the increase of the output-voltage magnitude, in order to meet the classical design levels of medium size motors in the lower megawatt power range [1], [2], [3], [4]. In all well-known multilevel topologies, generally a regular or symmetric voltage share over all partial sources has been chosen, with as main goal a better use of the individual silicon devices regarding the possible blocking propertie

This work deals with the modelling of electrochemical reactors with bipolar electrodes. We give a numerical model which enables us to compute electrical current and potential distributions in an electrochemical cell of any type of geometry in two and three dimensions, including electrodes at an unknown floating potential. We first present electrochemical reactors and particularly insist on kinetics and thermodynamics phenomena responsible on potential discontinuities at electrodes-electrolyte interfaces. Se

Ozone prodn. in 5M H2SO4 with Ti/IrO2/SnO2 - Sb2O5 electrodes was studied. Electrodes were prepd. at 550 Deg by spray pyrolysis of a soln. of precursors contg. tin and antimony chlorides. The aim of this work was to elucidate the mechanism of activation and deactivation of Ti/IrO2/SnO2-Sb2O5 electrodes for ozone prodn. Under galvanostatic conditions the anodic potential and O3 prodn. increases firstly reaching a max. then suddenly decrease. The authors explain this observation by considering that the SnO2 l

Degradation of asymmetrical Pt/SRO/PLZT/Pt capacitors: Role of Pt and oxide electrodes

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Modelling of finite-gap and zero-gap alkaline water electrolyser configurations for gas bubble management and optimisation

Hybrid Symmetrizing Voltage-Clamp for Voltage Balancing of Two-Level Operated 3L-NPC Topology

Hybrid Symmetrizing Voltage-Clamp Design for an IGCT-Based Direct Current Transformer

A noise reduction circuit technique for CMOS terahertz imaging

Head-to-head and tail-to-tail 180^{°} domain walls in an isolated ferroelectric

First-principles description of ferroelectric/electrode interfaces and properties of not very thin ferroelectric capacitors

Nature of nonlinear imprint in ferroelectric films and long-term prediction of polarization loss in ferroelectric memories

On tower impedances for transient analysis

Positional order in lead scandium tantalate (PST) as a "tool" for the investigation of relaxor ferroelectric behavior in thin films

Power modulation capabilities of the 140 GHz/1 MW gyrotron for the stellarator Wendelstein 7-X

Manufacture of micro-electro-mechanical-system using sacrificial layer made of silicon, useful for micro-electro-mechanical-system device architecture, e.g. radio-frequency capacitive switch and current switch

Extrinsic contributions to the piezoelectric response of lead-based ferroelectrics

Dielectric breakdown in (Pb,La)(Zr,Ti)O-3 ferroelectric thin films with Pt and oxide electrodes

High resolution study of domain nucleation and growth during polarization switching in Pb(Zr,Ti)O-3 ferroelectric thin film capacitors

Asymmetric Multilevel Converter for High Resolution Voltage Phasor Generation

Numerical modelling of potential and current distributions in a bipolar electrolytic cell

Use of Ti/IrO2/SnO2-Sb2O5 electrodes for ozone production