Search results for "Conversion"
showing 10 items of 707 documents
Preparation of mixed oxides MNdO3, with M=Cr, Fe. Comparison of several methods
1993
Abstract Different methods for the formation of NdCrO3 and NdFeO3, having the perovskite-like structure, were studied including the ceramic method, simultaneous precipitation of hydroxides and simultaneous crystallization from aqueous solutions of nitrates. Preparation of mixed oxides from hydroxides simultaneously precipitated lowered the temperature and time required for their formation. In the case of NdCrO3 the formation process from hydroxides and nitrates occurred through the chromate, NdCrO4, without intermediate decomposition of the precursor to metal oxides, which lead to the mixed oxide by 600°C.
Ordering of fluorite-type phases in erbium-doped oxyfluoride glass ceramics
2018
In this study, novel transparent Er3+ doped glass ceramics were prepared from melt-quenched oxyfluoride glasses with general composition of Na2O-NaF-BaF2-YbF3-Al2O3-SiO2. The crystallization of fluorite (BaF2, BaF2-YbF3, NaF-BaF2-YbF3 and Na0.5-xYb0.5+xF2+2x) and distorted fluorite (rhombohedral Ba4Yb3F17 and tetragonal NaF-BaF2-YbF3) phases was analysed in glass ceramics with different BaF2 and YbF3 ratio. The phase composition and microstructure were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Intense red upconversion luminescence (UCL) was detected under near-infrared excitation resulting from three photon upconversion followed by cross-relaxation betw…
Porphyrin Antenna-Enriched BODIPY–Thiophene Copolymer for Efficient Solar Cells
2018
International audience; Low bandgap A−π–D copolymer, P(BdP-DEHT), consisting of alternating BOronDIPYrromethene (BODIPY) and thiophene units bridged by ethynyl linkers, and its porphyrin-enriched analogue, P(BdP/Por-DEHT), were prepared, and their optical and electrochemical properties were studied. P(BdP-DEHT) exhibits strong absorption in the 500–800 nm range with an optical bandgap of 1.74 eV. On the basis of cyclic voltammetry, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels are evaluated to be −5.40 and −3.66 eV, respectively. After the anchoring of zinc(II) porphyrin on the BODIPY unit, P(BdP/Por-DEHT) displays broadened absor…
Electronic Band Transitions in γ-Ge3N4
2021
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. Support from Estonian Research Council grant PUT PRG 619 is gratefully acknowledged. The multi-anvil experiments at LMV were supported by the French Government Laboratory of Excellence initiative no ANR-10-LABX-0006, the Région Auvergne and the European Regional Development Fund (ClerVolc Contribution Number 478).
Upconversion Nanocarriers Encapsulated with Photoactivatable Ru Complexes for Near-Infrared Light-Regulated Enzyme Activity.
2017
Enzyme activity is important for metabolism, cell functions, and treating diseases. However, remote control of enzyme activity in deep tissue remains a challenge. This study demonstrates near-infrared (NIR) light-regulated enzyme activity in living cells based on upconverting nanoparticles (UCNPs) and a photoactivatable Ru complex. The Ru complex is a caged enzyme inhibitor that can be activated by blue light. To prepare a nanocarrier for NIR photoinhibition of enzyme activity, a UCNP and the caged enzyme inhibitors are encapsulated in a hollow mesoporous silica nanoparticle. In such a nanocarrier, the UCNP can harvest NIR light and convert it into blue light, which can activate the caged e…
Improvement of the electrochemical behaviour of Zn-electroplated steel using regenerated Cr(III) passivation baths
2014
[EN] Conversion coatings based on trivalent chromium are more sensitive to the presence of zinc and iron impurities than the chromate formulations. This fact contributes to a decrease in the quality of passivation and to the generation of a significant amount of hazardous liquid waste. Recently, a new eco-innovative process based on Emulsion Pertraction Technology (EPT) is being implemented at industrial scale for selectively removing Zn and Fe from spent passivation baths in order to enhance the lifetime of the Cr (III) baths. In this study, the effect of Zn and Fe removal on the electrochemical behaviour of Zn-electroplated steel samples was evaluated by means of polarisation curves and e…
Influence of Iron Sulfide Nanoparticle Sizes in Solid‐State Batteries**
2021
Abstract Given the inherent performance limitations of intercalation‐based lithium‐ion batteries, solid‐state conversion batteries are promising systems for future energy storage. A high specific capacity and natural abundancy make iron disulfide (FeS2) a promising cathode‐active material. In this work, FeS2 nanoparticles were prepared solvothermally. By adjusting the synthesis conditions, samples with average particle diameters between 10 nm and 35 nm were synthesized. The electrochemical performance was evaluated in solid‐state cells with a Li‐argyrodite solid electrolyte. While the reduction of FeS2 was found to be irreversible in the initial discharge, a stable cycling of the reduced sp…
Magnetic and magneto-optical properties of nickel hexacyanoferrate/chromate thin films
2017
One of the most important challenges of modern science and technology is the quest for novel and tuneable materials, the properties of which can be widely controlled by chemical modifications or external stimuli. Simultaneously, an interest in the development of magnetic thin films also gains significant attention. In the current paper we bring together both these challenges and present a study of a new type of low-dimensional nickel hexacyanoferrate/chromate system. Thin films were obtained by the "layer by layer" deposition technique, where the ratio of Fe/Cr was controlled by the dipping sequence. The scope of this work is a comprehensive analysis of structural, spectroscopic and magneti…
Photophysical properties of the triangular [Au(HNCOH)]3 complex and its dimer
2020
Rate constants for radiative and non-radiative transitions of the [Au(HNCOH)]3 complex and its dimer were calculated within the Herzberg–Teller approximation based on quantum mechanical principles. A high triplet quantum yield was estimated for the monomer. Internal conversion (IC) was found to be the major competing process to the intersystem crossing (ISC) from the lowest excited singlet state (S1) to the lowest triplet state (T1). ISC and IC from the spin-mixed 1 state also dominate the triplet relaxation process resulting in a negligible phosphorescence quantum yield for the monomer. The IC and ISC rate constants of the dimer are considerably smaller due to much lower Franck–Condon fact…
Boosting inverted perovskite solar cell performance by using 9,9-bis(4-diphenylaminophenyl)fluorene functionalized with triphenylamine as a dopant-fr…
2019
In this study, two newly developed small molecules based on 9,9-bis(4-diphenylaminophenyl)fluorene functionalized with triphenylamine moieties, namely TPA-2,7-FLTPA-TPA and TPA-3,6-FLTPA-TPA, are designed, synthesized and characterized. The electrochemical, optical and thermal properties of both materials are investigated using various techniques. Afterwards, these materials are employed as dopant-free hole transporting materials (HTMs) in planar inverted perovskite solar cell devices with the aim of determining the device performance and studying their stability in comparison with reference N4,N4,N4′′,N4′′-tetra([1,10-biphenyl]-4-yl)-[1,1′:4′,1′′-terphenyl]-4,4′′-diamine (TaTm)-based devic…