bluuebunny/crossref_metadata_2025_split huggingface dataset:
Whether Ge-Rich ZrO2 and Ge-Rich HfO2 Materials Have Similar Reaction on Annealing Treatment?
Authors: Khomenkova Larysa , Lehninger David , Agocs Emil , Petrik Peter , Portier Xavier , Korsunska Nadiia , Melnichuk Oleksandr , Gourbilleau Fabrice , Heitmann Johannes 
Published: May 2020

Usually, HfO2 and ZrO2 are considered as twin-oxides that have to demonstrate similar reaction on their doping with group IV elements as well as stable tetragonal “high-k” phase. However, in most cases the films produced with different approaches were compared. In this work, both Ge doped HfO2 and Ge-doped ZrO2 films were prepared using the same equipment that allows the same Ge content in both materials to be achieved via monitoring of deposition conditions. Thus, the effect of Ge content and thermal treatment on optical and structural properties of these films was studied to obtain direct experimental confirmation whether the formation of corresponding solid solutions and their phase separation stimulated by thermal treatment is similar for both oxides.
The films were grown on 6-inch Si wafers by confocal magnetron sputtering using the deposition unit with installed Ge, HfO2 and ZrO2 targets simultaneously. After the deposition, the wafers with the films were cut on smaller samples and rapid thermal annealing in nitrogen atmosphere was performed at 300-900ºC during 30 s. The samples were investigated by means of spectroscopic ellipsometry, Raman scattering, FTIR and TEM methods.
As-deposited pure ZrO2 and Ge-ZrO2 films as well as those annealed at TA≤600°C were found to be amorphous and homogeneous. Annealing at higher TA stimulates a phase separation and a formation of Ge nanoclusters (Ge-ncs). They crystallize at TC=640-700°C showing the tendency to the TC decrease with Ge content rise. An appearance of tetragonal ZrO2 phase in Ge-rich films was observed at TC=680-700°C. Such behavior of ZrO2 host shows the possibility to form Ge-ncs in amorphous matrix at TA=640-680°C that offers success application of such films.
Contrary to pure ZrO2 films, as-deposited pure HfO2 films were found to be crystalline. Their doping with [Ge]≥5at% reduces the degree of film crystallinity towards amorphous structure that was found to be stable for TA£600°C. At higher TA the formation of Ge-ncs and tetragonal HfO2 phase was detected. However, this latter was found to be formed at TC=600-670 °C, while the Ge-ncs crystallize at TC=700-800°C. Note that the formation of larger Ge-ncs in Ge-ZrO2 films than that in Ge-HfO2 ones at the same annealing conditions was observed.
Obtained results support the theoretical consideration about stability of tetragonal “high-k” phases in annealed films. However, they show also the difference in the reaction of Ge-HfO2 and Ge-ZrO2 materials on thermal treatment followed by phase separation. Its mechanism will be discussed in details.
(Invited) Garnet-Based Hybrid Composite Electrolytes for the All-Solid-State Li-S Battery
Authors: Bag Sourav , Thangadurai Venkataraman 
Published: May 2020

Lithium sulfur (Li-S) batteries have emerged as one of the most promising post LIBs technologies with a remarkably high theoretical energy density and abundance of elemental sulfur. Nonetheless, there are many problems associated with lithium sulfur batteries such as safety hazard due to lithium dendrite formation and fast capacity decay due to polysulfide dissolution effect.1 Solid electrolytes are promising to prevent lithium dendrite formation and polysulfide dissolution. Among different ceramic electrolytes garnet-type solid inorganic electrolytes are very promising because of its high ionic conductivity and stability with metallic lithium. But the high interfacial resistance with the electrode is the major bottleneck for the practical use of garnet electrolyte.2 However, polymer-based solid electrolytes possess low interfacial resistance but associated low ionic conductivity at room temperature is the biggest challenge for the utilization in solid-state-batteries.3

Recent research theme of Thangadurai group is mainly focused on garnet-type and polymer-garnet composite electrolytes for the practical utilization in all-solid-state Li batteries. Surface modifications of the garnet-type electrolytes and novel composite electrolytes developed in the laboratory have been successfully employed in all-solid-state-Li-S batteries even at room temperature. Fabrication of these electrolytes in bulk scale, characterizations, electrochemical properties and all-solid-state-Li-S battery performances will be discussed.
References:
1. Manthiram, A.; Fu, Y.; Chung, S.; Zu, C.; Su, Y. Chem. Rev.
2014, 114, 11751-11787.
2. Han, X.; Gong, Y.; Fu, K.; He, X.; Hitz, G.; Dai, J.; Pearse, A.; Liu, B.; Wang, H.; Rubloff, G.; Mo, Y.; Thangadurai, V.; Wachsman, E.; Hu, L. Nat. Mater.
2016, 16, 572-579.
3. Zhou, C.; Bag, S.; Thangadurai, V. ACS Energy Lett.
2018, 3, 2181-2198.
4. Bag, S.; Zhou, C.; Kim, P.; Pol, V. G.; Thangadurai, V. Energy Storage Mater.
2019 (doi.org/10.1016/j.ensm.2019.08.019)
(Invited) Photoelectrochemical Properties of All-Inorganic Core/Shell Silicon Quantum Dots
Authors: Fujii Minoru , Sugimoto Hiroshi 
Published: May 2020

Silicon (Si) quantum dots (QDs) are an environmentally friendly nano-functional material potentially suitable for biophotonics applications. Recently, we have developed a new type of all-inorganic Si QDs that can be dispersed in water almost perfectly without organic ligands and exhibit size-dependent photoluminescence (PL) in the near-infrared range in water [1-2]. The unique property of the QDs arises from the unique structure achieved by simultaneous doping of boron (B) and phosphorus (P). The figure shows a typical transmission electron microscope (TEM) image of a B and P codoped Si QD [3]. The lattice fringe corresponds to {111} planes of crystalline Si. On the surface of the crystalline core, an amorphous shell is formed. The shell is composed of Si, B and P, the concentration of B and P being in the range from a few % to 10 at.%. The shell induces negative potential on the surface and prevents agglomeration of Si QDs in polar solvents by the electrostatic repulsion. To the ligand-free surface of codoped Si QDs, molecules in a solution can access easily, and thus a variety of charge-transfer-induced phenomena such as a photocatalytic effect and chemical doping are expected [4-5]. In a codoped Si QD, B and P are also doped in the crystalline core. Formation of donor and acceptor states in the band gap strongly modifies the luminescence property. Combination of the quantum size effect and the doping effect leads to the control of the luminescence energy in the range much wider than that of conventional Si QDs [6, 7]. By comparing the luminescence energy with those obtained by theoretical calculations, we estimate the number of active B and P pairs in a Si QD to be 2-10 depending on the doping concentration and the size. In the presentation, we will discuss the luminescence and photoelectrochemical properties, including photocatalytic hydrogen evolution, of the B and P codoped Si QDs.

References

[1] M. Fujii, H. Sugimoto, and S. Kano, Chem. Commun., Vol. 54, 4375 (2018).
[2] M. Fujii, H. Sugimoto, and K. Imakita, Nanotechnology, Vol. 27, 262001 (2016).
[3] H. Sugimoto, et al., Nanoscale, Vol. 10, 7357 (2018).
[4] T. Kojima, H. Sugimoto, and M. Fujii, J. Phys. Chem. C, Vol. 122, 1874 (2018).
[5] K. Inoue, T. Kojima, H. Sugimoto, and M. Fujii, J. Phys. Chem. C, Vol. 123, 1512. (2019).
[6] H. Sugimoto, et al., J. Phys. Chem. C, Vol. 117, 11850 (2013).
[7] H. Sugimoto, et al., Nano Letters, Vol. 18, 7282 (2018).

Figure 1
(Invited) Towards Tm2+ in Sialon Thin Films Grown by Sputtering Using the Gradient Deposition
Authors: Bosco Giacomo , van der Kolk Erik 
Published: May 2020

There are different material candidates for efficient industry compatible luminescence solar concentrators to be used in electricity generating glass applications. Among them, divalent thulium (Tm2+) doping has been shown to have a high potential. It has been reported to have 65% absorption of the solar spectral range when in di-halide hosts, while showing no self-absorption and a relatively neutral colour [1]. These characteristics are possible because Tm2+ has a strong absorption from the UV up to about 900 nm. This absorption is generated by intense 4f
13 → 4f
125d
1 electronic transitions and a single emission line at 1140 nm, credited to the 2F5/2 → 2F7/2 transition of the 4f
13 configuration. However, this specific oxidation state of thulium is rather anomalous: so far it was only stabilized on di-halide crystals. These crystals are very hygroscopic in nature, therefore not sufficiently attractive for scaling up in industry standard thin film growth techniques. Thus, it is necessary to research on the possible extension in the list of materials able to host such a promising optically active element. However, the intrinsic complex nature of the lanthanide’s electronic structure has prevented a detailed understanding of the valence stability of its elements. Therefore, designing industry compatible hosts ensuring that such exotic ion is stable and capable of efficiently emitting NIR light is a challenging task.
In this work, I show the progress made so far towards unravelling the conditions for stabilization of the Tm2+ in industry compatible thin film materials – more specifically, thin film materials of the SiAlON family. I report recent results on Tm doped SiAlON thin films grown by combinatorial magnetron reactive sputtering. The gradient characterization method [2], developed at the TU Delft’s luminescence materials research group, was used in order to relate position dependent film composition – determined by energy dispersive x-ray spectroscopy – with local transmission, photoluminescence emission and excitation data. This singular approach makes it possible to retrieve a wide composition range in a smaller number of different films. These results are discussed upon the valence stability model of lanthanides of Dorenbos [3], and the model of impurity ionization adopted in solid state statistics.

References

[1] O. M. ten Kate, K. W. Krämer, and E. van der Kolk, “Efficient luminescent solar concentrators based on self-absorption free, Tm 2+ doped halides,” Sol. Energy Mater. Sol. Cells, vol. 140, pp. 115–120, Sep. 2015.
[2] E. P. J. Merkx and E. van der Kolk, “Method for the Detailed Characterization of Cosputtered Inorganic Luminescent Material Libraries,” ACS Comb. Sci., vol. 20, no. 11, pp. 595–601, Nov. 2018.
[3] P. Dorenbos, “Valence stability of lanthanide ions in inorganic compounds,” Chem.
Mater., vol. 17, no. 25, pp. 6452–6456, Dec. 2005.
(Invited) Lanthanide Doped Nanoparticles and Their Applications
Authors: Vetrone Fiorenzo 
Published: May 2020

Since approximately 2000, lanthanide doped nanoparticles have received significant attention due to their interesting luminescent properties. At the core of this interest is their ability to convert near-infrared excitation light (typically 980 or 800 nm) to higher energies spanning the ultraviolet, visible and near-infrared regions of the spectrum through a multiphoton process known as upconversion. Upconversion differs from conventional multiphoton excitation in other materials where no real intermediate states are present necessitating the use of ultrafast lasers (in the femtosecond regime) for simultaneous excitation to the upper emitting state. The lanthanide ions possess a multitude of 4f electronic states that have long lifetimes (micro- to millisecond) thus act as population reservoirs in the upconversion process. Hence, upconversion occurs through real, long-lived intermediate states through a sequential photon absorption process. This eliminates the need for ultrafast excitation and as a result, upconversion can be observed using inexpensive, continuous wave diode lasers. Upconversion luminescence can be exploited for a number of applications in nanomedicine, theranostics, photovoltaics, photocatalysis, as well as many others.
While their upconversion luminescence has been studied in great detail, lanthanide doped nanoparticles can also emit in the near-infrared through a direct Stokes (down-shifted) luminescence process. Of particular importance is that these near-infrared emissions lie within the biological windows where biological tissues are optically transparent. For obvious reasons, a great deal of the work on the nanomedicine and theranostics applications of lanthanide doped nanoparticles has shifted to their near-infrared luminescence properties.
In this presentation, we will demonstrate the synthesis of these nanoparticles, establish how changing their nanoscale architecture can affect their luminescence properties (both upconversion and near-infrared), and discuss their potential applications, particularly in nanomedicine.
(Invited) Understanding the Role of Protein Corona on Oligonucleotide Recognition Efficiency in Fluorescent Flares
Authors: Wang Hao , Lee Ki-Bum , Fabris Laura 
Published: May 2020

Nanoparticle-based biosensors are developed and implemented to address a wide range of biomedical questions in bioimaging, molecular diagnostics, targeted drug delivery and controlled release, or photothermal cancer therapy. In this respect, gold nanoparticles provide physicochemical and optical properties that make them particularly interesting. Their relevant, and often unique, plasmonic response has enabled their integration with various transduction modalities (e.g. colorimetric, fluorescence, Raman) and led to the development of extremely sensitive and selective detection platforms. Added advantages associated with gold nanoparticles are their excellent biocompatibility and low toxicity compared to some other nanomaterials (notably quantum dots and silver nanoparticles) when used for sensing and imaging purposes in vivo.
In recent years, the performance of gold nanoparticles in the biological milieu has attracted substantial interest. It is well known that, when employing nanoparticles in in vivo studies, proteins present in the biological environment contribute to opsonization, a process that leads to the recognition and attack by macrophages and systematic clearance. For in vitro applications, this process can affect instead the performance of the nanoparticle-based sensors, by reducing in particular sensitivity and selectivity. In both instances, the culprit is the rapid formation of a protein corona around the nanoparticle, which hinders the interaction of any responsive moiety conjugated to its surface with the target molecules present in the surrounding environment. In this talk, I will discuss how the formation of protein corona affects the response of fluorescent flares as they are employed to identify target oligonucleotides in solution. By monitoring the fluorescent response that originates upon hybridization of the nanoflares with their targets, we determined that protein corona, regardless of the identity of the proteins employed to mimic the biological environment, negatively impacts the hybridization dynamics, leading to a reduction in sensitivity by almost 20%, compared to the 2 nM LODs in the absence of corona. We also observed that the presence of protein corona leads to reduced resistance to nucleases, with different effects that depend on the size of the specific proteins, leading us to hypothesize the importance of steric hindrance. Finally, and surprisingly, we observed that polyethylene glycol (PEG) functionalization does not substantially improve the performance of the flares, with further reduced sensitivity due to the lower number of recognition moieties that can be accommodated on the nanoparticle’s surface when PEG is also introduced. We believe that these results will offer further quantitative insight useful for the development of in vivo and in vitro probes based on gold nanoparticles.
(Invited) Nanoscale Llight Management Using Three-Dimensional Scanning Near-Field Optical Microscopy
Authors: Fanchini Giovanni 
Published: May 2020

In this talk, we will present an overview of aperture and apertureless type scanning near-field optical microscopy (SNOM) techniques that have been developed for the characterization of photonics-grade nanoscale materials, with a focus on three-dimensional (3D) SNOM methods. 3D SNOM has been undertaken to image the local distribution (within ~100 nm of the surface) of the electromagnetic radiation scattered by random and deterministic arrays of
metal nanostructures or photonic crystal waveguides. Individual metal nanoparticles and metal nanoparticle arrays exhibit unique effects under light illumination, including plasmon resonance and waveguiding properties, which can be directly investigated using 3D-SNOM. In the second part of this article, we will review a few applications in which 3D-SNOM has proven to be useful for designing and understanding specific nano-optoelectronic structures and photonic materials. Examples will include the analysis of the nano-optical response phonetic crystal waveguides, aperture antennae and metal nanoparticle arrays, as well as the design of plasmonic solar cells incorporating random arrays of copper nanoparticles as an optical absorption enhancement layer, and the use of 3D-SNOM to probe multiple components of the electric and magnetic near-fields without requiring specially designed probe tips. A common denominator of these examples is the added value provided by 3D-SNOM in predicting the properties-performance relationship of nanostructured systems in photonics grade materials.
Manufacturing Impact on Electrochemical and Mechanical Performance of NMC Cathodes Via Mesoscale Simulation
Authors: Ferraro Mark E. , Trembacki Bradley L. , Brunini Victor E. , Noble David R. , Roberts Scott A. 
Published: May 2020

Lithium-ion battery performance is determined by numerous coupled multi-physics effects which can be tuned through various manufacturing methods. Electrode calendering pressure can compress local mesostructures, shortening conductive pathways and introducing contact points where mechanical stresses manifest. The addition of a secondary conductive binder phase alters ionic and electronic conduction pathways, limits available surface area for reaction, and buffers mechanical contacts. Coupled physics simulation can visualize localized behaviors that arise from altering these macroscale conditions.
Here, we use a mesoscale simulation approach to explore the influence of manufacturing conditions on the performance of an NMC333 half-cell. Image-based particle representations are combined with the Conformal Decomposition Finite Element Mesh (CDFEM) algorithm to provide a conformal, solvable mesh for coupled electrochemical/mechanical simulations. Resolution at this particle scale allows analysis of localized phenomena dependent on particle size, shape, and local mesostructure. Our discussion will detail the limiting physics and variations across domains of four different calendering pressures (0, 300, 600, 2000 bar) and conductive binder fraction (90, 92, 94, 96wt% active material). Per-particle analyses will quantify differences between mesostructures and discuss how local variations influence macroscale properties like cell pressure, effective conductivity, and the discharge curve. Furthermore, we will discuss the statistical effects of domain sample selection on electrode-scale behaviors. This mesoscale analysis allows us to isolate the most significant limiting factors for discharge performance, providing suggestions for future battery design.
Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Unveiling the Mechanisms Leading to the ‘Green’ Synthesis of Metal Oxide Quantum Dots By Plasma Induced Non-Equilibrium Electrochemistry (PINE)
Authors: Padmanaban Dilli babu , McGlynn Ruairi James , Maguire Paul , Mariotti Davide 
Published: May 2020

The synthesis of a range of metal oxide quantum dots (QDs) has been demonstrated in the past few years utilizing plasma-induced non-equilibrium electrochemistry (PiNE).1
-
4These reports have also shown important features of these QDs with benefits for energy and other applications. The synthesis process has shown a generalized approach for metal oxide QDs that include Cu, Mo, Zn, Ni, Mn and Co. In this contribution we will first overview the opportunities offered by this technique for metal oxides. We will then report on an in-depth investigation to understand the mechanisms and reaction pathways leading to the formation of QDs. This will be mainly based on the synthesis of CuO QDs (< 5 nm diameter), however we will also attempt to extrapolate our findings to understand the synthesis of other metal oxides, highlighting any differences. In particular, we carried out extensive characterization of both the QDs as well as the electrolyte. In addition to materials characterization techniques, we used Fourier transform infra-red spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and gas chromatography-mass (GC-MS) spectroscopy. Further, measurements for pH and other trace products were also carried out as well as optical emission spectroscopy. Overall our work discloses important general aspects of plasma-liquid interactions, in particular when ethanol is used. The specific synthesis of CuO QDs follows a ‘green’ synthesis cycle that only produces water as by-product with traces of hydrogen peroxide and isopropanol.

Reference

(1) Velusamy, T.; Liguori, A.; Macias-Montero, M.; Padmanaban, D. B.; Carolan, D.; Gherardi, M.; Colombo, V.; Maguire, P.; Svrcek, V.; Mariotti, D. Plasma Process. Polym.
2017, 14 (7), 1600224.
(2) Ni, C.; Carolan, D.; Rocks, C.; Hui, J.; Fang, Z.; Padmanaban, D. B.; Ni, J.; Xie, D.; Maguire, P.; Irvine, J. T. S.; Mariotti, D. Green Chem.
2018, 20 (9), 2101–2109.
(3) Ni, C.; Carolan, D.; Hui, J.; Rocks, C.; Padmanaban, D.; Ni, J.; Xie, D.; Fang, Z.; Irvine, J.; Maguire, P.; Mariotti, D. Cryst. Growth Des.
2019, 19 (9), 5249–5257.
(4) Chakrabarti, S.; Carolan, D.; Alessi, B.; Maguire, P.; Svrcek, V.; Mariotti, D. Nanoscale Adv.
2019.