Search results for "electric [charge]"
showing 10 items of 729 documents
Nanowires: A route to efficient thermoelectric devices
2019
Miniaturization of electronic devices aims at manufacturing ever smaller products, from mesoscopic to nanoscopic sizes. This trend is challenging because the increased levels of dissipated power demands a better understanding of heat transport in small volumes. A significant amount of the consumed energy in electronics is transformed into heat and dissipated to the environment. Thermoelectric materials offer the possibility to harness dissipated energy and make devices less energy-demanding. Heat-to-electricity conversion requires materials with a strongly suppressed thermal conductivity but still high electronic conduction. Nanowires can meet nicely these two requirements because enhanced …
Magnéli oxides as promising <em>n</em>-type thermoelectrics
2014
The discovery of a large thermopower in cobalt oxides in 1997 lead to a surge of interest in oxides for thermoelectric application. Whereas conversion efficiencies of p-type oxides can compete with non-oxide materials, n-type oxides show significantly lower thermoelectric performances. In this context so-called Magneli oxides have recently gained attention as promising n-type thermoelectrics. A combination of crystallographic shear and intrinsic disorder lead to relatively low thermal conductivities and metallic-like electrical conductivities in Magneli oxides. Current peak-zT values of 0.3 around 1100 K for titanium and tungsten Magneli oxides are encouraging for future research. Here, we …
Electrochemical impedance spectroscopy for studying passive layers on steel rebars immersed in alkaline solutions simulating concrete pores
2007
Present paper deals with the use of the electrochemical impedance spectroscopy to identify different processes in the passive layer growth over steel rebar surface immersed in an alkaline media simulating the concrete pore solution. Two cases have been considered: a passive layer spontaneously grown in a high alkaline media and a passive layer assisted by the application of an anodic potential in the same media. The application of electric equivalent circuits allows distinguishing between the different mechanisms occurring in this passive layer when grows in different conditions. An electric equivalent circuit with two RC loops connected in parallel is often used for fitting the EIS diagram…
Thermoelectric properties of spark-plasma sintered nanoparticular FeSb2prepared via a solution chemistry approach
2013
Nanoparticular FeSb2 was prepared in solution from cyclopentadienyl iron(ii) dicarbonyl dimer [Fe(Cp(CO)2)]2 and antimony nanoparticles. Spark plasma sintering was used as consolidation method to maintain the particle size. The thermoelectric performance of FeSb2 is limited by its high thermal conductivity. In this work, the thermal conductivity was suppressed by nearly 80% compared to the bulk value by introducing grain boundary scattering of phonons on the nanoscale. The thermoelectric properties of the consolidated FeSb2 emphasize the possibility of altering thermal transport of promising thermoelectric compounds by phonon scattering by engineering the interfaces at the nanoscale.
Anisotropic lattice thermal conductivity in topological semimetal ZrGeX (X = S, Se, Te): a first-principles study
2021
Abstract Topological semimetals have attracted significant attentions owing to their potential applications in numerous fields such as low-power electron devices and quantum computation, which are closely related to their thermal transport properties. In this work, the phonon transport properties of topological Dirac nodal-line semimetals ZrGeX (X = S, Se, Te) with the PbClF-type structures are systematically studied using the first-principles calculations combined with the Boltzmann transport theory. The obtained lattice thermal conductivities show an obvious anisotropy, which is caused by the layer structures of ZrGeX (X = S, Se, Te). The room-temperature lattice conductivity of ZrGeTe al…
Photoelectric response of localized states in silica glass
2019
This work was supported by the Latvian Science Council Grant No lzp-2018/1-0289.
Pyroelectric activity of LiGaO2, Li2GeO3, Li2B4O7 and LiNbO3 crystals: Pyroelectric luminescence and excitation of cathodoluminescence in scintillato…
2020
Abstract Basing on results of electric, spectral and kinetic measurements of spontaneous luminescence caused by cooling/heating in pyroelectric crystals LiGaO2, Li2GeO3, Li2B4O7 and LiNbO3 a mechanism of pyroelectric luminescence is proposed. Series of experiments were undertaken attaching a scintillating phosphor ScPO4 to a pyroelectric crystal and subjecting a pair of the bounded crystals to cooling/heating process. Pyroelectric activity causes not only pyroluminescence in pyroelectric crystals but also luminescence in a ScPO4, which is characterized with high intensity and kinetic and spectral properties typical for the intrinsic luminescence of a scintillator.
Transient photoresponse and incident power dependence of high-efficiency germanium quantum dot photodetectors
2012
We report a systematic study of time-resolved and power-dependent photoresponse in high-efficiency germanium quantum dot photodetectors (Ge-QD PDs), with internal quantum efficiencies greater than 100 over a broad wavelength, reverse bias, and incident power range. Turn-on and turn-off response times (τ on and τ off) are shown to depend on series resistance, bias, optical power, and thickness (W QD) of the Ge-QD layer, with measured τ off values down to ∼40 ns. Two different photoconduction regimes are observed at low and high reverse bias, with a transition around -3 V. A transient current overshoot phenomenon is also observed, which depends on bias and illumination power. © 2012 American …
Superconductor-ferromagnet tunnel junction thermoelectric bolometer and calorimeter with a SQUID readout
2020
Superconductor-ferromagnet thermoelectric detector (SFTED) is a novel ultrasensitive radiation detector based on the giant thermoelectric effect in superconductor-ferromagnet tunnel junctions. This type of detector can be operated without the need of additional bias lines, and is predicted to provide a performance rivaling transition-edge sensors and kinetic inductance detectors. Here we report our numerical studies on the SFTED noise equivalent power, energy resolution and time constant, and the feasibility of a SQUID readout in both bolometric and calorimetric regimes, with the goal to provide practical design parameters for the detector fabrication and the readout circuitry implementatio…
The strain response of piezoelectric multilayer actuators under combined action of electric field and in-plane uniform load
1997
Abstract The driving field governed strain of lead zirconate titanate piezoelectric multilayer actuators have been made within the 107 N/m2 stress and the 3 · 106 V/m triangle-like upward-down-ward driving voltage. A slow strain component as well as a specific relaxation pattern are detected being additional to the periodic part and attributed to the trapped space charge effects favored by nonuniform electric field of the multilayer.