High-temperature-grown buffer layer boosts electron mobility in epitaxial La-doped BaSnO3_3/SrZrO3_3 heterostructures

By inserting a SrZrO$_3$ buffer layer between the film and the substrate, we demonstrate a significant reduction of the threading dislocation density with an associated improvement of the electron mobility in La:BaSnO$_3$ films. A room temperature mobility of 140 cm$^2$ V$^{-1}\text{s}^{-1}$ is achieved for 25-nm-thick films without any post-growth treatment. The density of threading dislocations is only $4.9\times 10^{9}$ cm$^{-2}$ for buffered films prepared on (110) TbScO$_3$ substrates by pulsed laser deposition.Comment: 5 pages, 4 figure

High-efficiency photothermal water evaporation using broadband solar energy harvesting by ultrablack silicon structures

Development of broadband absorption materials for solar energy harvesting is an important strategy to address global energy issues. Herein, it is demonstrated that an ultrablack silicon structure with abundant surface texturing can absorb about 98.7% solar light within the wavelength range of 300 to 2500 nm, i.e., a very large range and amount. Under 1 sun irradiation, the ultrablack silicon sample's surface temperature can increase from 21.2 to 51.2 °C in 15 min. During the photothermal water evaporation process, the ultrablack silicon sample's surface temperature can still reach a highest temperature of 43.2 °C. The average photothermal conversion efficiency (PTCE) can be as high as 72.96%. The excellent photothermal performance to the excellent light-trapping ability of the pyramidal surface nanostructures during solar illumination, which leads to extremely efficient absorption of light, is attributed. In addition, the large water contact area also enables fast vapor transport. The stability of the photothermal converter is also examined, presenting excellent structure and performance stabilities over 10 cycles. This indicates that the ultrablack Si absorber can be a promising photothermal conversion material for seawater desalination, water purification, photothermal therapy, and more

Prokaryotic respiration and production in the meso- and bathypelagic realm of the eastern and western North Atlantic basin

We measured prokaryotic production and respiration in the major water masses of the North Atlantic down to a depth of,4,000 m by following the progression of the two branches of North Atlantic Deep Water (NADW) in the oceanic conveyor belt. Prokaryotic abundance decreased exponentially with depth from 3 to 0.4 3 105 cells mL21 in the eastern basin and from 3.6 to 0.3 3 105 cells mL21 in the western basin. Prokaryotic production measured via 3H-leucine incorporation showed a similar pattern to that of prokaryotic abundance and decreased with depth from 9.2 to 1.1 mmol C m23 d21 in the eastern and from 20.6 to 1.2 mmol C m23 d21 in the western basin. Prokaryotic respiration, measured via oxygen consumption, ranged from about 300 to 60 mmol C m23 d21 from,100 m depth to the NADW. Prokaryotic growth efficiencies of,2 % in the deep waters (depth range 1,200–4,000 m) indicate that the prokaryotic carbon demand exceeds dissolved organic matter input and surface primary production by 2 orders of magnitude. Cell-specific prokaryotic production was rather constant throughout the water column, ranging from 15 to 32 3 1023 fmol C cell21 d21 in the eastern and from 35 to 58

Determination of the liquid-phase speciation in the MDEA-H2O-CO2 system

AbstractAqueous solutions of alkanolamines are commonly used in CO2 capture processes. To describe these complex processes rigorous mass transfer models are needed, in which all mass transfer, kinetics and thermodynamics are incorporated correctly. To improve the quality of the thermodynamic models, not only commonly used P-α (CO2 partial pressure versus CO2 liquid loading) experimental data, but also liquid phase speciation data are important. Speciation data of amine-H2O-CO2 data are very scarce in literature. In this work speciation data of MDEA-H2O-CO2 have been determined experimentally with a Fourier Transform Infra-Red spectrometer (FTIR) at ambient temperature. After several calibration lines were prepared, the speciation of this system was determined online in the FTIR. The experimental data presented in this work were well in line with speciation from open literature

A cryogenic testbed for the characterisation of large detector arrays for astronomical and Earth-observing applications in the near to very-long-wavelength infrared

In this paper we describe a cryogenic testbed designed to offer complete characterisation-via a minimal number of experimental configurations— of mercury cadmium telluride (MCT) detector arrays for low-photon background applications, including exoplanet science and solar system exploration. Specifically, the testbed offers a platform to measure the dark current of detector arrays at various temperatures, whilst also characterising their optical response in numerous spectral bands. The average modulation transfer function (MTF) can be found in both dimensions of the array along with the overall quantum efficiency. Working from a liquid-helium bath allows for measurement of arrays from 4.2 K and active-temperature control of the surface to which the array is mounted allows for characterisation of arrays at temperatures up to 80 K, with the temperature of the array holder known to an accuracy of at least 1 mK, with the same level of long-term stability

Far-Field Radiation of Three-Dimensional Plasmonic Gold Tapers near Apexes

International audienceThree-dimensional plasmonic gold tapers are widely used structures in nano-optics for achieving imaging at the nanometer scale, enhanced spectroscopy, confined light sources, and ultrafast photoelectron emission. To understand their radiation properties further, especially in the proximity of the apex at the nanoscale, we employ cathodoluminescence spectroscopy with high spatial and energy resolution. The plasmon-induced radiation in the visible spectral range from three-dimensional gold tapers with opening angles of 13°and 47°is investigated under local electron excitation. We observe a much weaker radiation from the apex of the 13°taper than from that of the 47°taper. By means of finite-difference time-domain simulations we show that for small opening angles plasmon modes that are created at the apex are efficiently guided along the taper shaft. In contrast for tapers with larger opening angles, generated plasmon polaritons experience larger radiation damping. Interestingly, we find for both tapers that the most intense radiation comes from locations a few hundreds of nanometers behind the apexes, instead of exactly at the apexes. Our findings provide useful details for the design of plasmonic gold tapers as confined light sources or light absorbers

Fast northward energy transfer in the Atlantic due to Agulhas rings

The adiabatic transit time of wave energy radiated by an Agulhas ring released in the South Atlantic Ocean to the North Atlantic Ocean is investigated in a two-layer ocean model. Of particular interest is the arrival time of baroclinic energy in the northern part of the Atlantic, because it is related to variations in the meridional overturning circulation. The influence of the Mid-Atlantic Ridge is also studied, because it allows for the conversion from barotropic to baroclinic wave energy and the generation of topographic waves. Barotropic energy from the ring is present in the northern part of the model basin within 10 days. From that time, the barotropic energy keeps rising to attain a maximum 500 days after initiation. This is independent of the presence or absence of a ridge in the model basin. Without a ridge in the model, the travel time of the baroclinic signal is 1300 days. This time is similar to the transit time of the ring from the eastern to the western coast of the model basin. In the presence of the ridge, the baroclinic signal arrives in the northern part of the model basin after approximately 10 days, which is the same time scale as that of the barotropic signal. It is apparent that the ridge can facilitate the energy conversion from barotropic to baroclinic waves and the slow baroclinic adjustment can be bypassed. The meridional overturning circulation, parameterized in two ways as either a purely barotropic or a purely baroclinic phenomenon, also responds after 1300 days. The ring temporarily increases the overturning strength. Th presence of the ridge does not alter the time scales

Negatively Charged In-Plane and Out-Of-Plane Domain Walls with Oxygen-Vacancy Agglomerations in a Ca-Doped Bismuth-Ferrite Thin Film.

The interaction of oxygen vacancies and ferroelectric domain walls is of great scientific interest because it leads to different domain-structure behaviors. Here, we use high-resolution scanning transmission electron microscopy to study the ferroelectric domain structure and oxygen-vacancy ordering in a compressively strained Bi0.9Ca0.1FeO3-δ thin film. It was found that atomic plates, in which agglomerated oxygen vacancies are ordered, appear without any periodicity between the plates in out-of-plane and in-plane orientation. The oxygen non-stoichiometry with δ ≈ 1 in FeO2-δ planes is identical in both orientations and shows no preference. Within the plates, the oxygen vacancies form 1D channels in a pseudocubic [010] direction with a high number of vacancies that alternate with oxygen columns with few vacancies. These plates of oxygen vacancies always coincide with charged domain walls in a tail-to-tail configuration. Defects such as ordered oxygen vacancies are thereby known to lead to a pinning effect of the ferroelectric domain walls (causing application-critical aspects, such as fatigue mechanisms and countering of retention failure) and to have a critical influence on the domain-wall conductivity. Thus, intentional oxygen vacancy defect engineering could be useful for the design of multiferroic devices with advanced functionality