Li7La3Zr2O12 films were prepared on polycrystalline Al2O3 by metal organic chemical vapor deposition. The effect of deposition temperature (Tsub) on the phase formation, morphology and deposition ...rates was investigated. Tetragonal Li7La3Zr2O12 film formed at Tsub=1023–1173K. The morphology changed from small-sized granular, polygonally faceted granular to flat and smooth surface with increasing Tsub. Cubic Li7La3Zr2O12 film with fine granular surface was deposited at Tsub=1173–1223K. The deposition rates of the cubic and tetragonal Li7La3Zr2O12 films were approximately 20μmh−1, which were one to two orders of magnitude greater than those of Li7La3Zr2O12 films by pulsed laser deposition.
•Cubic and tetragonal Li7La3Zr2O12 films were prepared by MOCVD.•Single-phase cubic Li7La3Zr2O12 film showed fine granular morphology.•Tetragonal Li7La3Zr2O12 film had polygonally faceted granular and columnar structure.•The highest deposition rate was 21.6μmh−1 for Li7La3Zr2O12 film.•(111)- and (100)-oriented La2Zr2O7 films were deposited.
A roll milled complex of Polyaniline (PANI) and Dodecylbenzenesulphonic acid (DBSA) is used with a cross-linked polymer Divinylbenzene (DVB), to prepare a conductive thermoset matrix with good ...environmental stability at room temperature. Upon heating, thermal doping of PANI-DBSA and curing of DVB occur simultaneously. Different amounts of DVB are used to prepare different samples and their properties are determined. Electrical & mechanical properties are measured. It has been shown that the electrical properties and mechanical properties of the composites are inversely proportional. It is demonstrated that the flexural modulus increases with an increase in DVB content, while the conductivity increases with an increase in PANI-DBSA content. The composite using roll-milled PANI-DBSA complex has shown better stability but lower electrical and mechanical properties as compared to the composite prepared using centrifugally mixed PANI-DBSA complex. An environmentally stable PANI-DBSA/DVB conductive thermosetting matrix is introduced in this work. FTIR spectra and UV–vis–NIR spectra are obtained to explain the effect of roll milling on PANI-DBSA and also the effect of DVB concentration on the composite. Thermal stability of the composites is determined using TGA analysis. The morphology of the samples is studied using SEM and the conductivity behavior is explained.
Cationic polymerization of DVB polymer (a) Initiation and growth reaction (b) Terminal reaction (c) PANI doping. Display omitted
•A highly environmentally stable PANI-DBSA/DVB conductive thermosetting matrix is prepared and characterized.•Dedoping phenomenon of the PANI in the system is explained using UV–vis–NIR spectra.•Effect of PANI agglomerations and free DBSA on environmental stability of the composite has been explained.
The magnetoelectric effect-the induction of magnetization by means of an electric field and induction of polarization by means of a magnetic field-was first presumed to exist by Pierre Curie, and ...subsequently attracted a great deal of interest in the 1960s and 1970s (refs 2-4). More recently, related studies on magnetic ferroelectrics have signalled a revival of interest in this phenomenon. From a technological point of view, the mutual control of electric and magnetic properties is an attractive possibility, but the number of candidate materials is limited and the effects are typically too small to be useful in applications. Here we report the discovery of ferroelectricity in a perovskite manganite, TbMnO3, where the effect of spin frustration causes sinusoidal antiferromagnetic ordering. The modulated magnetic structure is accompanied by a magnetoelastically induced lattice modulation, and with the emergence of a spontaneous polarization. In the magnetic ferroelectric TbMnO3, we found gigantic magnetoelectric and magnetocapacitance effects, which can be attributed to switching of the electric polarization induced by magnetic fields. Frustrated spin systems therefore provide a new area to search for magnetoelectric media.
Synthetic saponite containing a photosensitizing metal complex was complexed with colloidal anatase and used for the visible light photocatalytic reaction of aqueous benzene to phenol. The addition ...of phenol to the initial aqueous benzene solution was effective in improving the reaction yield and the product selectivity.
Synthetic saponite containing a photosensitizing metal complex was complexed with colloidal anatase and used for the visible light photocatalytic reaction of aqueous benzene to phenol.
The effects of water content, temperature and loading rate on the strength and failure process of rock at sub-zero temperatures were investigated and are presented in this paper. Over the range of ...temperatures studied there was little change observed in the properties of dry rock. The presence of water in the rock, however, resulted in a marked increase in rock strength and the fracture initiation stress. Rock strength increased with amount of water present and the rate of load application, with the effect being exacerbated at the colder temperatures. Interestingly, the changes in strength were not uniform as there was a greater rate of increase in the tensile strength of rock with temperature than compressive strength. It is postulated that these changes in mechanical properties may be explained in part by a reduction in the stress concentration within the interstitial spaces and cracks of the rock samples tested.
•Strength and deformation of dry and wet rocks were examined at sub-zero temperature.•Effect of temperature and loading rate on strength of frozen rocks were clarified.•Failure process of frozen rocks was considered by deformation behaviors.•A mechanism of increase in fracture initiation stress due to pore ice was proposed.
Despite many studies on seafloor hydrothermal systems conducted to date, the generation mechanism of seafloor massive sulfide (SMS) deposits is not yet fully understood. To elucidate this mechanism, ...this study clarifies the three‐dimensional regional temperature distribution and fluid flow of a seafloor hydrothermal system of the Iheya North Knoll, middle Okinawa Trough. Lateral flow and boiling of hydrothermal fluids below a caprock were the main features found by the simulation. A caprock formation generated by anhydrite precipitation and hydrothermal alteration is the most plausible cause of these features, because caprocks can increase the temperature and induce boiling of fluids by preventing seawater inflow. Such a formation also gradually makes the top of the conduit less permeable; thus, lateral flow occurs. Consequently, vapor‐rich hydrothermal fluids poor in metals are discharged from vents as white smokers, whereas liquid‐dominated hydrothermal fluids rich in metals flow laterally below the caprocks, forming subseafloor SMS deposits.
Plain Language Summary
In seafloor hydrothermal systems, the seawater heated by magma circulates under the seafloor and forms seafloor massive sulfide (SMS) deposits. Recently, SMS deposits have attracted interest as a new metal resource, the generation mechanism and model of which must be established for accurate resource exploration. However, the mechanism is not yet fully understood. To address this problem, we applied a hydrothermal flow simulation and clarified the temperature distribution and fluid flow in the Iheya North Knoll, southwestern Japan. The result revealed that lateral flow and boiling of hydrothermal fluids occur below the seafloor. A low permeability caprock formation generated by anhydrite and clay mineral development is the most plausible cause of these occurrences, because a caprock can increase the temperature and induce boiling of fluids by suppressing the seawater inflow. This formation also makes fluid outlets less permeable, thus induces lateral flow. Consequently, vapor‐rich hydrothermal fluids poor in metals are discharged from vents, while liquid‐dominated hydrothermal fluids rich in metals flow laterally below the caprocks, forming subseafloor SMS deposits.
Key Points
Numerical simulation of multiphase fluid flow revealed regional temperature, fluid‐flow patterns, and physical property distributions
Integration of results with geologic interpretations provided a plausible generation mechanism of seafloor massive sulfide deposits
Formation of caprocks below the seafloor induces boiling and lateral flow of hydrothermal fluid and, consequently, the deposit generation
The relationships among magnetism, lattice modulation, and dielectric properties have been investigated for RMnO3 (R=Eu, Gd, Tb, and Dy). These compounds show a transition to an incommensurate ...lattice structure below their Néel temperature, and subsequently undergo an incommensurate-commensurate (IC-C) phase transition. For TbMnO3 and DyMnO3 it was found that the IC-C transition is accompanied by a ferroelectric transition, associated with a lattice modulation in the C phase. DyMnO3 shows a gigantic magnetocapacitance with a change of dielectric constant up to Deltaepsilon/epsilon approximately 500%.
Li electrodeposition on liquid Ga substrates was carried out in PC-LiClO4 at 40 °C. It was found that interfacial flow phenomena were induced by differences in interfacial tension between the liquid ...Ga and the liquid Ga-Li alloy formed on the substrate under potentiostatic electrolysis at −1.0 V (vs. Li+/Li), which caused the interfacial shape change of the liquid Ga electrode. We carried out in-situ observations in order to understand why such interfacial phenomena occur between the liquid electrolyte and the liquid metal cathode. Moreover, a significant difference in electrochemical response between liquid and solid Ga substrates was also noticed employing the current-time transient technique. These experimental results suggest that the process of liquid Ga-Li phase formation by the dissolution of electrodeposited Li atoms into the liquid Ga substrate dominated during the initial stage of Li electrodeposition. In contrast, the typical peaks induced by growth of solid Ga-Li alloy phase and Li metal phase were observed on solid Ga substrates. These results provide new insight into the design of electrochemical processing involving liquid electrolyte/liquid metal interface.
•Li electrodeposition on both liquid and solid Ga cathodes in propylene carbonate containing LiClO4 was carried out.•Interfacial flow phenomena induced by differences in interfacial tension between Ga(l) and Ga-Li(l) alloy were observed.•The electrochemical response is related to the formation of the liquid Ga-Li alloy phase on the liquid Ga cathodes.•Future work should take into account macroscopic hydrodynamics induced by electrochemical reactions on liquid metal cathodes.
Although seafloor massive sulfide (SMS) deposits are crucially important metal resources that contain high‐grade metals such as copper, lead, and zinc, their internal structures and generation ...mechanisms remain unclear. This study obtained detailed near‐seafloor images of electrical resistivity in a hydrothermal field off Okinawa, southwestern Japan, using deep‐towed marine electrical resistivity tomography. The image clarified a semi‐layered resistivity structure, interpreted as SMS deposits exposed on the seafloor, and another deep‐seated SMS layer at about 40‐m depth below the seafloor. The images reinforce our inference of a new mechanism of SMS evolution: Upwelling hydrothermal fluid is trapped under less‐permeable cap rock. The deeper embedded SMS accumulates there. Then hydrothermal fluids expelled on the seafloor form exposed SMS deposits.
Plain Language Summary
Hydrothermal circulation of seawater through the permeable ocean crust engenders formation of seafloor massive sulfide (SMS) deposits, which present high potential for metal mining. Geophysical surveys using modes such as electrical and electromagnetic methods have revealed that SMS deposits exhibit lower resistivity than the surrounding host rock. However, because detailed geophysical images of internal structures of SMS deposits are lacking, the spatial distribution of SMS deposits and the evolutionary processes of SMS deposits remain unclear. For this study, we applied a deep‐towed marine electrical resistivity tomography (ERT) system to capture detailed images of electrical resistivity structures of SMS deposits in the Iheya North hydrothermal field, Okinawa Trough, southwestern Japan. An optimal sub‐seafloor resistivity section reveals a semi‐layered structure consisting of double low‐resistivity SMS layers: exposed and deep‐seated ones. Between the SMS layers, a cap rock layer is recognized as a moderately resistive zone. This detailed structure offers an explanation of how the SMS deposits accumulate: Hydrothermal fluids upwelling from the deep crust are trapped by less‐permeable cap rock, which results in the precipitation and accumulation of SMS deposits below the cap rock. Then fluids passing through the cap rock to the seafloor produce SMS deposits on the seafloor.
Key Points
Deep‐towed marine electrical resistivity tomography revealed massive sulfide deposits on the seafloor as low‐resistivity zones
Low‐resistivity zones are semi‐layered with deposits exposed on the seafloor and other deposits at 40‐m depth below the seafloor
Detailed near‐seafloor images of electrical resistivity offer an explanation of how the SMS deposits accumulate
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