bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Theory of Radiative Lifetime of an Activator Ion Due to Surface Plasmons
Authors: Mishra Kailash C. , Piquette Alan , Collins John 
Published: February 2020

One means of controlling the color, brightness, and directional profile of light emitted from LEDs or luminescent materials, in general, is through the use of nanostructures. Metallic films and structures are a particular class of material that have been of considerable interest for this purpose in recent times. In this talk, we consider the lifetime and efficiency of a phosphor layer situated near a metallic film.
We will first make general observations of the effects of the plasmons on the lifetime and quantum efficiency of the activator ions in the phosphor and on the role of the plasmons in the emission process. The effect of the plasmons in the excitation process and on the total luminescence from the system will also be discussed.
Finally, an expression for the lifetime of the optical ions interacting with the surface plasmon modes will be derived using the relevant Einstein A and B coefficient. This requires a determination of the mode density of the surface plasmons. Since the surface plasmons represent a 2-dimensional system, a length parameter must be introduced in order to calculate the mode density. We derive this parameter using a semi-classical approach, and show its dependence on the dielectric constants of the system and on the distance from the metallic layer.
(Invited) Eu2+-Doped KxNa1-XLuS2 Ternary Sulfides: Application and Perspectives in White LEDs
Authors: Jary Vitezslav , Havlak Lubomir , Barta Jan , Bystricky Ales , Rejman Martin , Nikl Martin , Martin Lisa I D J , Joos Jonas J , Smet Philippe F 
Published: February 2020

The presented work gives an overview of recent advances in research and development of novel phosphors based on Eu2+-doped KxNa1-xLuS2 ternary sulfides which may be used as phosphors in white LED sources with tunable color correlated temperature. Tunability is achieved by using two different kinds of excitation diodes (nearUV and blue) in combination with the proper K/Na ratio in KxNa1-xLuS2:Eu2+ structure. Intense photoluminescence due to the Eu2+ 5d – 4f allowed transition covers a broad emission region in visible range under both nearUV (~390 nm) and blue (~450 nm) excitations. The possibility to change the intensity ratio of the excitation diodes yields the changes of the output color correlated temperature. These changes are clearly demonstrated by shifts in the CIE color space; light quality is also quantified and discussed using CRI (color rendering index) and CQS (color quality scale) metrics [1].
However, to fully understand the Eu2+ emission mechanisms in these sulfidic hosts and to be able to optimize phosphor preparation and its performance, additional experimental techniques are applied to characterize these KxNa1-xLuS2:Eu2+ phosphors. When a focused electron beam impinges on a cathodoluminescent (CL) material in a scanning electron microscope (SEM), secondary electrons, characteristic x-rays and visible photons are emitted. These signals can be used to construct a two-dimensional topographical, chemical and luminescence map, respectively [2]. Furthermore, thermal quenching and quantum efficiency measurements of KxNa1-xLuS2:Eu2+ phosphors will be discussed for the first time.

V. Jarý, L. Havlák, J. Bárta, M. Rejman, A. Bystřický, Ch. Dujardin, G. Ledoux, M. Nikl. Circadian Light Source Based on KxNa1-xLuS2:Eu2+ Phosphor. ECS Journal of Solid State Science and Technology, 7 (1), R3182-R3188, (2018). doi: 10.1149/2.0231801jss.

L.I.D.J. Martin, D. Poelman, P.F. Smet, J.J. Joos, Microscopic Study of Dopant Distribution in Europium Doped SrGa2S4: Impact on Thermal Quenching and Phosphor Performance. ECS Journal of Solid State Science and Technology, 7 (1) R3052-R3056 (2018). doi: 10.1149/2.0341709jss.
Surface and Subsurface Effects in Electrochemical Water Splitting
Authors: Tavassol Hadi , Bloed Charles , Vuong Jiam , Siwabessy Andrew , Shelden Calum , Enriquez Alexis 
Published: February 2020

We will report on the surface and subsurface electrode processes in aqueous solutions. We are particularly focused on anode and cathode processes in electrochemical water splitting. Well-defined model electrode materials of oxides and noble metal alloys are prepared to investigate structural and mechanistic details of water splitting.
Gas phase synthesis and controlled atmosphere electrochemical analysis of oxygen evolution electrocatalysis of CaxSr1-xFe2O6-δ perovskites where δ = 0-1, will be discussed. This system exhibits a wide range of activity depending on the A site composition. Our results suggest that surface and subsurface oxygen content controls the oxygen evolution catalysis. Although, current understanding from the d-orbital electron count (eg occupancy) predicts low OER activities for such a system, under specific solution conditions, some of the compounds in the Sr2-xCaxFe2O6-δ series exhibit higher activity than LaCoO3. We particularly use results of in-situ vibrational spectroscopy and electrochemical analysis to elucidate vacancy content and ordering effects on catalysis.
We will also discuss the influence of surface and subsurface structures of model Pt-M (M = Cu and Ni) surface alloys and bilayers during hydrogen adsorption relevant to hydrogen evolution reaction (HER). We use electrochemical measurements and in-situ surface stress analysis of these systems to elucidate activity trends from hydrogen adsorption affinities. Our results exhibit a correlation between the energetics of hydrogen underpotential deposition and HER catalytic activity.
Catalytic Activity Enhancement in Oxygen Evolution Reaction on LDH Nanosheets By Metal-Cluster Loading
Authors: Kitano Sho , Yamauchi Miho 
Published: February 2020

Electrochemical water splitting enables to store electricity produced from intermittent renewable solar and wind energy resources in the form of H2. Development of highly active electrocatalysts for kinetically sluggish anode reaction, i.e., oxygen evolution reaction (OER) remains a major challenge for several decades. Recently, metal hydroxide nanosheets exfoliated from layered double hydroxide composed of Ni2+ and Fe3+ (NiFe-LDH) were found to show excellent catalytic activities for OER. However, a high overpotential on LDH was still required to accelerate OER. Considering that Fe sites are regarded as a catalytic site and the overpotential for OER on the LDH nanosheet catalysts depends on a binding energy between intermediate molecules and Fe sites, modification of electronic structure of LDH probably controls the binding states and enhances catalytic activities on LDH. In this study, we prepare NiFe-LDH nanosheets (NiFe-NS) decorated with Au clusters and examine influence of the Au loading both on electronic states of Fe sites and catalytic activities of the NS.
NiFe-LDH was synthesized by hydrothermal method and colloidal Au clusters were prepared in DMF as reported previously. Carbonate ions in NiFe-LDH were exchanged to perchlorate ions, and the perchlorate ion–intercalated sample was dispersed in formamide, resulting in formation of colloidal NiFe-NS solution. Au-cluster-loaded NiFe-NS (Au/NiFe-NS) was prepared by mixing colloidal solutions of the NiFe-NS and Au clusters. Scanning TEM measurements revealed that small Au clusters around 1.2 nm in diameter are homogeneously dispersed on LDH.
Fig. 1 shows iR-corrected polarization curves of pristine NiFe-NS, Au clusters and Au/NiFe-NS electrocatalysts in 1 M KOH aqueous solution. The Au/NiFe-NS exhibited much larger oxidation current at a lower potential than the pristine NiFe-NS whereas Au clusters showed negligible activity, indicating that catalytic activity of NiFe-NS was significantly enhanced through the Au-cluster loading. XPS and XAFS measurements elucidated that Fe sites of Au/NiFe-NS are in more reduced states compared to those in the pristine NiFe-NS, resulting from charge transfer from Au clusters to Fe sites. Since bond breaking between the Fe site and intermediates is a rate determining step, we then conclude that reduction of Fe ions contributes to weaken binding energy and enhance catalytic activities. We achieved enhancement of catalytic activities of NiFe-NS via modification of electronic states of Fe sites using charge transfer interaction induced by Au cluster loading.
Fig. 1 IR-corrected polarization curves for OER on pristine NiFe-NS, Au clusters and Au/NiFe-NS in 1 M KOH aqueous solution.

Figure 1
Sn-Cu Codeposition from Non-Aqueous Solvents for Wafer Bonding Applications: A Pulse Plating Study
Authors: Pallaro Mattia , Panzeri Gabriele , Magagnin Luca 
Published: February 2020

Eutectic wafer bonding is being investigated in industry and research due to the possibility to work at relatively low temperature and, at the same time, to obtain a metallic junction that offers greater reliability compared with other materials, such as polymers or glass[1]. In this work, electrodeposition of Sn-Cu alloy suitable for wafer bonding is studied using ethylene glycol as a solvent: this non-aqueous solvent is used for its promising properties, such as a wider electrochemical window in comparison with commercial solutions[2,3]. Several Sn-Cu solutions are tested with different concentrations of the two metal precursors and are characterized electrochemically, by cyclic voltammetry and linear sweep voltammetry. Deposition is performed both in direct and pulsed current mode, and the advantages of the latter are observed. The effects of pulse plating on the microstructure of the deposits are then investigated, by changing parameters as duty cycle, frequency and the shape of the pulses.
Figure 1 (see attachment): SEM morphologies of two samples deposited in direct current (a) and in pulsed current mode (b).
[1] C. C. Lee, C. Y. Wang, and G. S. Matijasevic, “A new bonding technology using gold and tin multilayer composite structures,” IEEE Trans. Compon. Hybrids Manuf. Technol., vol. 14, no. 2, pp. 407–412, Jun. 1991.
[2] H. M. Maltanava, T. N. Vorobyova, and O. N. Vrublevskaya, “Electrodeposition of tin coatings from ethylene glycol and propylene glycol electrolytes,” Surf. Coat. Technol., vol. 254, pp. 388–397, Sep. 2014.
[3] A. P. Abbott, A. I. Alhaji, K. S. Ryder, M. Horne, and T. Rodopoulos, “Electrodeposition of copper–tin alloys using deep eutectic solvents,” Trans. IMF, vol. 94, no. 2, pp. 104–113, Mar. 2016.

Figure 1
Influence of Molar Ratio of CaO to TiO2 on Ti Electrodeposition in Molten CaCl2
Authors: Okada Haruka , Murata Maito , Morishige Taiki , Takenaka Toshihide 
Published: February 2020

A new efficiency process of Ti production replacing Kroll process is desired. The authors proposed the direct electrowinning of liquid Ti considering its advantage in term of productive efficiency. Our previous study showed that calcium titanate was dissolved in molten CaCl2, and that the type of calcium titanate affected the reduction behavior of Ti. These results indicated that Ti reduction in molten CaCl2 depends on the molar ratio of CaO to TiO2 (RCaO/TiO2, hereinafter).
In this study, the influence of RCaO/TiO2 on Ti reduction reaction was investigated by cyclic voltammetry at 1373K ~ 1573K using the bath of RCaO/TiO2 = 1.0 ~ 2.0, and electrodeposition by potentio-static electrolysis was attempted. Typical cyclic voltammograms in the bath of various RCaO/TiO2 were shown in Fig.1. Although no sharp current peak was seen, some current peak/humps appeared; three current peak/humps were observed in the bath of RCaO/TiO2 = 1.0 and 1.325, while two current peak/humps were seen in the bath of RCaO/TiO2 = 1.5, 1.8 and 2.0. These results suggest that stable Ti-O complex ions change with RCaO/TiO2, and that they affect the Ti reduction.
Titanium metal was obtained by potentio-static electrolysis regardless of RCaO/TiO2, but the situation of Ti metal deposition depended on RCaO/TiO2 and the electrolysis potential; Ca metal was apt to co-deposited with Ti metal deposition in the bath of RCaO/TiO2 = 1.0 and 1.325, while Ti metal was obtained without Ca co-deposition in the bath of RCaO/TiO2 = 1.5, 1.8 and 2.0. The suitable electrolytic potential for Ti metal deposition without Ca co-deposition seemed around -1.8V (vs. Mo dissolution potential).
From the reseachers by cyclic voltammetry and potentio-static electrolysis, it was shown that the electrodeposition of Ti metal in molten CaCl2 containing TiO2 strongly depended on the bath composition and the electrolytic potential deposition. The suitable molar ratio of CaO to TiO2, RCaO/TiO2, in the bath is thought to be around, and the suitable potential was -1.8V.

Figure 1
Tunable Reversible Ionic Liquids: Structurally Determined Property Manipulation
Authors: Biddinger Elizabeth J , Jung Sungyup , Podder Showmik , Chen Josephine 
Published: February 2020

Reversible ionic liquids (RevILs) are a class of solvents which are promising for a range of applications. RevILs have shown structurally dependent properties by changing their functional group and exhibited dramatic property changes between their molecular liquid (ML) and ionic liquid (IL) states. These unique characteristics of RevILs suggest a method of creating a suite of designer solvents that meet various chemical applications[1, 2]. The concept of “reversibility” lies in the ability of the RevIL to switch from ML to IL with CO2 addition and to switch back from IL to ML with a mild heating, showing dramatic difference of properties [1]. Non-electrochemical applications using RevIL systems include CO2 capture and separation [1].
The RevIL will exist in the ionically-insulating and relatively non-polar ML state, as synthesized, while IL state can be ionically conducting and relatively polar compared to the ML. Additionally, the RevIL properties will change as different functional groups are introduced. The tunability and switchability of the RevILs also make them promising for alternative uses in electrochemical systems[3].
This work investigates the feasibility of RevIL switchable solvents for use as switchable electrolytes in electrochemical applications. Silylamine RevILs are used in this study, and their properties as switchable electrolytes including conductivity, viscosity, and reversibility are primarily investigated. We will also show the change of properties as functional group changes. The change in conductivity and viscosity have signaled the possibility of implementing silylamines as a co-solvent in battery electrolytes to serve as a thermally-activated safety switch. Because these electrolytes have phase change from IL to ML with polarity and conductivity change at reversal temperature, the reversal temperature has also been studied to provide information about the temperature dynamics of the IL.
[1] J.R. Switzer, A.L. Ethier, E.C. Hart, K.M. Flack, A.C. Rumple, J.C. Donaldson, A.T. Bembry, O.M. Scott, E.J. Biddinger, M. Talreja, M.G. Song, P. Pollet, C.A. Eckert, C.L. Liotta, Design, synthesis, and evaluation of nonaqueous silylamines for efficient CO2 capture, ChemSusChem, 7 (2014) 299-307.
[2] P.G. Jessop, D.J. Heldebrant, X. Li, C.A. Eckert, C.L. Liotta, Reversible nonpolar-to-polar solvent, Nature, 436 (2005) 1102.
[3] J.D. Jimenez, S. Jung, E.J. Biddinger, Ionicity analysis of silylamine-type reversible ionic liquids as a model switchable electrolyte, Journal of the Electrochemical Society, 162 (2015) H460-H465.
Negative Pressure Regimes in Ionic Liquids: Structure and Interactions in Stretched Liquids as Probed by NMR
Authors: Silva Wagner , Veiga Helena Isabel M. , Tariq Mohammad , Cabrita Eurico J. , Esperança José M.S.S. , Canongia Lopes José N. , Rebelo Luis Paulo N. 
Published: February 2020

Condensed matter - solids or liquids, but not gases - might be deeply, homogeneously stretched to absolute negative pressures (metastable regimes of isotropic tension). For instance, we were able to stretch macroscopically-sized liquid solutions down to p ~ - 35 MPa,[1] a value which still constitutes a world record for large volume liquid samples. Up to now, the absolute record for neat liquids is hold for liquid water in microscopic porous crevices of natural rocks, p ~ -140 MPa.
There are several strategies to force a liquid entering into negative pressure regimes. The most common one is the Berthelot method.[2] Negative pressures can be either directly measured - via a highly elaborated Bourdon-Berthelot combination methodology[3,4] or safely, though approximately, estimated through the liquid’s isochoric thermal-pressure coefficient, g
v = a
p/k
T.
In this work, a broad pallete of macroscopically sized samples of ionic liquids was used, in which tensions of about -100 MPa were obtained before cavitation would occur. This value constitutes a new record for large samples. The underlying success for achieving such great absolute negative pressures in ionic liquids as compared to other liquids seems to be the best combination of (i) their negligible vapour pressure and (ii) their generally high viscosity. Good adhesion (wettability) to the container’s walls (in this case Pyrex glass) is a paramount, minimum requirement.
For the first time, NMR studies have been performed on ionic liquids under homogeneous tension. Due to potential hazard issues related to the protection/safety of the NMR instrumentation, negative pressures beyond the value of – 20 MPa were avoided. Upon entering into these metastable regimes of negative pressure, it was possible to observe a sharp increase in the ions self-diffusion coefficients as compared to the equilibrium saturated liquid conditions at the same temperatures.
MD simulations have been performed to gain insights into the ILs structure and interactions under these deep metastable conditions.

References:

P. Visak, L.P.N. Rebelo, J. Szydlowski, J. Phys. Chem. B 107 (2003) 9837-9846.

Imre, K. Martinás, L.P.N. Rebelo, J. Non-Equil.Thermodyn. 23 (1998) 351-375.

I.M. Veiga et al., Int. J. Thermophys. 22 (2001) 1159-1174.

P.N. Rebelo et al., in “Liquids Under Negative Pressure”, Eds.: A.R. Imre, H.J. Maris, and P.R. Williams, NATO Science Series, Vol. 84, Kluwer Academic Publishers, Dordrecht, pp. 95 – 108 (2002).
Photo-polymerized organic host network of ionogels for lithium batteries: effects of mesh size and of ethylene oxide content
Authors: Aidoud Djamel , Guy-Bouyssou Delphine , Guyomard Dominique , Le Bideau Jean , Lestriez Bernard 
Published: February 2020

Ionogels represent a route to biphasic materials, for the use of ionic liquids (ILs) for all-solid devices. Confining ILs within host networks enhances their averaged dynamics, resulting in improved charge transport. Fragility, short relaxation times, low viscosity, and good ionic conductivity, all them appear to be related to the IL / host network interface. The presence of ILs at interface neighborhood leads to the breakdown of aggregated, structured regions that are systematically found in bulk ILs. This “destructuration”,1 as well as segregative interactions at interface,2 coupled with percolation of the bicontinuous solid/liquid interface,3 make these materials very competitive among the existing solid electrolytes. Such approach could provide (i) a route to lower locally the viscosity of ILs, and (ii) an easier pathway for diffusion of charged species. Several types of ionogels demonstrate this effect, taking into account of fully inorganic, hybrid, polymeric or organic-inorganic host networks . This “all solid” approach can be applied to several electrochemical energy storage sources, including lithium batteries 2,4 and supercapacitors.5

Herein we will emphasize the results of systematic studies of the effect of size of confinement, either within pores of solids or within meshes of polymers.2,6 Besides the effect of the size of the confinement, the chemical nature of the host network is investigated. Several examples showed that the best properties were obtained on the basis of a good balance between features of host network and features of confined ionic liquid.
References:
[1] A. Guyomard-Lack et al., Phys. Chem. Chem. Phys., 16 (2014) 23639-23645.
[2] A. Guyomard-Lack et al., New J. Chem., 40 (2016) 4269-4276.
[3] C. V. Cerclier et al., Phys. Chem. Chem. Phys., 17 (2015) 29707—29713
[4] D. Aidoud et al., J. Power Sources, 330 (2016) 92-103
[5] M. Brachet et al., J. Mater. Chem. A, 4 (2016) 11835-11843.
[6] D. Aidoud et al., submitted.
(Invited) Electrochemical Synthesis of Metal and Semiconductor Nanostructures from Ionic Liquids
Authors: Borisenko Natalia 
Published: February 2020

Metal and semiconductor nanostructures are usually synthesized using vacuum techniques. Such processes are cost-intensive and need vacuum conditions for preparation thus making the semiconductors quite expensive. Electrodeposition is an alternative and relatively simple way to produce these materials. However for electrochemical synthesis, applying of a proper solvent is essential to produce metals and semiconductors. The electrodeposition from aqueous solutions is limited by a relatively low electrochemical stability of water. In the case of molten salts, high temperature is usually required for electrodeposition. Organic solvents are very volatile and many of them are quite toxic. The alternative to common electrolytes is to use ionic liquids (ILs), which exhibit wide electrochemical windows, good thermal stability, non-volatility, low toxicity and are liquid below 100 °C [1].
In this lecture we will show that ILs are well suited for the electrodeposition of metal and semiconductor nanostructures with various architectures. Consequently, metal (e.g. Ga, In, Zn, Al, Cu, etc.) and semiconductor (Si, Ge, SixGe1-x, etc.) nanowires, nanotubes and macroporous structures can be synthesized in ILs at room temperature by using template-assisted electrodeposition. Recently, these materials have received some attention as promising electrode materials in batteries [2]. Furthermore, III-V semiconductor (e.g. GaSb and InSb) nanowires can be directly synthesized at room temperature by electroless deposition [3]. Some nanowires (e.g. ZnS) can be obtained in ILs without any external template, which opens a new perspective for the synthesis of semiconductor nanostructures. The structure of the IL/electrode interface can significantly alter the deposition process that, in turn, may result in the deposits with various morphologies and properties. This offers the opportunity to influence the optical properties of obtained materials by changing the composition of the solvent.
[1] F. Endres, A. Abbott, D. R. MacFarlane, Electrodeposition from Ionic Liquids. 2nd Edition. 2017, Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA.
[2] M. Shapouri Ghazvini, G. Pulletikhurthi, Z. Liu, A. Prowald, S. Zein El Abedin, F. Endres, J. Solid State Electrochem., 19 (2015) 1453-1461.
[3] A. Lahiri, N. Boriseko, M. Olschewski, R. Gustus, J. Zahlbach, F. Endres, Angew. Chem. Int. Ed., 54(40) (2015) 11870-11874.