Sea ice strength development from freezing to melting in the Antarctic marginal ice zone

[EN] Sea ice growth in the Marginal Ice Zone of the Antarctic is one of the largest annual changes on earth with a huge impact on the global climate and ecology system. The principles of sea ice growth and melting in the MIZ of the Antarctic is yet not as well researched as its polar counterpart in the north.For this study, pancake ice, consolidated ice and floe ice were analyzed with a compression test in July, October and November 2019 in the marginal ice zone of the Antarctic. Newly formed pancake ice in July showed the highest compressive strength in the bottom layer (3 MPa), whereas consolidated ice was strongest at the top (5 MPa). Consolidated ice in October and November had the highest compressive strength in a middle layer with up to 13.5 MPa, the maximum strength at the top was 3 MPa. Floe ice, consisting of destroyed pack ice, did not show a clear strength development over sea ice depth.The SCALE cruises are funded by the South African National Research Foundation (NRF) through the South African National Antarctic Programme (SANAP), with contributions from the Department of Science and Innovation and the Department of Environmental Affairs. We are very grateful to the teams that have contributed to the success of the SCALE cruise in particular under the guidance of Marcello Vichi and J¨org Schröder.Paul, F.; Mielke, T.; Audh, R.; Lupascu, D. (2022). Sea ice strength development from freezing to melting in the Antarctic marginal ice zone. En Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference. Editorial Universitat Politècnica de València. 375-385. https://doi.org/10.4995/YIC2021.2021.12249OCS37538

Piezoelectric Characteristics of LiNbO3 Thin-film Heterostructures via Piezoresponse Force Microscopy

Electro-optic LiNbO3 thin films were deposited on Si(100) and Si(111) substrates using a radio-frequency magnetron sputtering process. The piezoelectric properties of the LiNbO3 films were investigated using the scanning probe microscopy in the piezoresponse mode. The obtained results show the high degree of grains orientation in polycrystalline structure. The piezoelectric modulus (dzz) was estimated to be 16 pm/V (for LiNbO3 / Si(100)) and 22 pm/V (for LiNbO3 / Si(111)) and the polarization about of 0.37 C·m – 2. These values are larger than those reported previously for LiNbO3 films. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3366

Magnetic properties of the Bi0.65La0.35Fe0.5Sc0.5O3 perovskite

Magnetic properties of polycrystalline multiferroic Bi0.65La0.35Fe0.5Sc0.5O3 synthesized under high-pressure (6 GPa) and high-temperature (1500 K) conditions were studied using a SQUID magnetometer technique. The temperature dependent static magnetic moment M was measured in both zero-field-cooled and field-cooled modes over the temperature range of 5-300 K in low magnetic field H = 0.02 kOe. The field dependent magnetization M(H) was measured in magnetic fields up to 50 kOe at different temperatures up to 230 K after zero-field cooling procedure. A long-range magnetic ordering of the antiferromagnetic type with a weak ferromagnetic contribution takes place below TN ≈ 220 K. Magnetic hysteresis loops taken below TN show a huge coercive field up to Hc ≈ 10 kOe, while the magnetic moment does not saturate up to 50 kOe. A strong effect of magnetic field on the magnetic properties of the compound has been found. Below TN ≈ 220 K the derivatives of the initial magnetization curves demonstrate the existence of a temperature-dependent anomaly in fields of H = 15÷25 kOe. The nature of the anomaly is unknown and requires additional study.publishe

Roadmap on organic inorganic hybrid perovskite semiconductors and devices

Metal halide perovskites are the first solution processed semiconductors that can compete in their functionality with conventional semiconductors, such as silicon. Over the past several years, perovskite semiconductors have reported breakthroughs in various optoelectronic devices, such as solar cells, photodetectors, light emitting and memory devices, and so on. Until now, perovskite semiconductors face challenges regarding their stability, reproducibility, and toxicity. In this Roadmap, we combine the expertise of chemistry, physics, and device engineering from leading experts in the perovskite research community to focus on the fundamental material properties, the fabrication methods, characterization and photophysical properties, perovskite devices, and current challenges in this field. We develop a comprehensive overview of the current state of the art and offer readers an informed perspective of where this field is heading and what challenges we have to overcome to get to successful commercializatio

Strong electrocaloric effect in lead-free 0.65Ba(Zr0.2Ti0.8)O3-0.35(Ba0.7Ca0.3)TiO3 ceramics obtained by direct measurements

International audienceStrong electrocaloric effect in lead-free 0.65Ba(Zr 0.2 Ti 0.8)O 3-0.35(Ba 0.7 Ca 0.3)TiO 3 ceramics obtained by direct measurements Solid solutions of (1 À x)Ba(Zr 0.2 Ti 0.8)O 3-x(Ba 0.7 Ca 0.3)TiO 3 promise to exhibit a large electrocaloric effect (ECE), because their Curie temperature and a multiphase coexistence region lie near room temperature. We report on direct measurements of the electrocaloric effect in bulk ceramics 0.65Ba(Zr 0.2 Ti 0.8)O 3-0.35(Ba 0.7 Ca 0.3)TiO 3 using a modified differential scanning calorimeter. The adiabatic temperature change reaches a value of DT EC ¼ 0.33 K at $65 C under an electric field of 20 kV/cm. It remains sizeable in a broad temperature interval above this temperature. Direct measurements of the ECE proved that the temperature change exceeds the indirect estimates derived from Maxwell relations by about$50%. The discrepancy is attributed to the relaxor character of this material. V C 2015 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4907774] During the last several years, an increased interest has been paid to the electrocaloric effect (ECE) in ferroelectric materials as a route to develop small, effective, low cost, and environmentally friendly solid-state refrigerators. 1,2 The ECE is defined as an adiabatic and reversible temperature change of a dielectric material when an electric field is applied or removed. 3 If the exchange of heat with the environment is enabled, it defines the change of entropy as a function of the applied electric field under isothermal conditions. 4,5 Since Mischenko et al. reported on the giant electro-caloric effect in PbZr 0.95 Ti 0.05 O 3 thin films in 2006, 6 the ECE has been reported for many different ferroelectric materials such as thick and thin films, 7–10 polymers, 11,12 bulk ceramics, 13,14 and single crystals. 15,16 In general, the ECE peaks are a few degrees above the ferroelectric-paraelectric phase transition. 1 The largest values have been achieved for thin films, 10 where much higher electric fields can be applied than to bulk materials. However, for application, the heating/ cooling capacity is the key factor. Hence, bulk materials, which have large enough heating/cooling capacity, are better suitable for mid-and large-scale cooling applications. 1 To compare the ECE in different materials, the ratio between induced temperature change and applied field, DT EC /DE, called the electrocaloric strength, has been introduced

Giant mechanically-mediated electrocaloric effect in ultrathin ferroelectric capacitors at room temperature

International audienceUsing a phenomenological approach, we demonstrate that a giant mechanically-mediated electrocaloric effect can be obtained in ultrathin ferroelectric SrRuO3/BaTiO3/SrRuO3 capacitors at room temperature. Our results show that the electrocaloric properties of such capacitors can be systematically tuned by applying an external stress. The depolarizing field, whose effect is usually ignored in the literature, is found to be detrimental to the electrocaloric response, especially for the thinner films. Moreover, a remarkable enhancement and broadening of the electrocaloric response can be achieved in relatively thick films under compressively loaded conditions compared with the unloaded case

Mono , Di , and Tri Valent Cation Doped BiFe0.95Mn0.05O3 Nanoparticles Ferroelectric Photocatalysts

The ferroelectricity of multivalent codoped Bismuth ferrite (BiFeO3; BFO) nanoparticles (NPs) is revealed and utilized for photocatalysis, exploiting their narrow electronic bandgap. The photocatalytic activity of ferroelectric photocatalysts BiFe0.95Mn0.05O3 (BFM) NPs and mono‐, di‐, or tri‐valent cations (Ag+, Ca2+, Dy3+; MDT) coincorporated BFM NPs are studied under ultrasonication and in acidic conditions. It is found that such doping enhances the photocatalytic activity of the ferroelectric NPs approximately three times. The correlation of the photocatalytic activity with structural, optical, and electrical properties of the doped NPs is established. The increase of spontaneous polarization by the mono‐ and tri‐valent doping is one of the major factors in enhancing the photocatalytic performance along with other factors such as stronger light absorption in the visible range, low recombination rate of charge carriers, and larger surface area of NPs. A‐site doping of BFO NPs by divalent elements suppresses the polarization, whereas trivalent (Dy3+) and monovalent (Ag+) cations provide an increase of polarization. The depolarization field in these single domain NPs acts as a driving force to mitigate recombination of the photoinduced charge carriers.The ferroelectricity of Ag/Ca/Dy‐doped BiFe0.95Mn0.05O3 nanoparticles are utilized for photocatalysis under ultrasonic conditions. The mitigated recombination of photoinduced charge‐carriers in the nanoparticles due to the depolarization field, is one of the important factors for the photocatalytic rate. The piezoresponse becomes a crucial parameter under ultrasonic conditions for ferroelectric photocatalysts. The pink dye (rhodamine B) is photodegraded using MDT doped nanoparticles. The ease of photoinduced charge carrier separation in single domain nanoparticles using the depolarization field as a driving force is shown. imageDeutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Peer Reviewe