bluuebunny/crossref_metadata_2025_split huggingface dataset:
White Light Emission of Polystyrene (PS) Thin Films Deposited by Spray Pyrolysis
Authors: Carmona S. , Alarcón G. , Zaleta E. , Agular-Frutis M. , Rivera Z. , Pineda A. , Murrieta H. , Falcony Ciro 
Published: February 2020

The optical, structural and luminescent characteristics of polystyrene PS films doped with luminescent organic pigments (LOP) and deposited by spray pyrolysis technique are reported. The films are deposited on glass, quartz and GaN at low temperatures, using chemical solutions of recycled PS (from stayfoam) and LOPs as precursors, and N.N-dimethylformamide, as solvent.
The thickness of the films was around 2.5 μm films showed at deposition rates between 100 and 200 Å/s. Doped films have roughness between 100 and 2500 Å depending on the kind of pigment used and the surface morphology shows that the organic pigments incorporate into the polystyrene host forming globular particles of about 2 µm in diameter. The organic pigments used have luminescent emissions peaked at 445, 510 and 590 nm.
Non-doped films are very transparent and smooth; on the other hand, doped films are opaque and rough. The LOPs luminescent emission wavelengths were preserved when they were incorporated in the PS films. Using an appropriate mix of OPs it was possible to obtain films that have white light emission. These multi doped films were deposited on violet and blue light emitting LED chips, achieving a complete white light source device. It was determined that the exposure to the violet light from the LED degrades the luminescent characteristics, however, the blue light has is not energetic enough to cause a degradation of the luminescent layer over similar period of time.
Emissions intensity behavior of photoluminescence depends of doping concentration and deposition temperature. The luminescence intensity had a maximum when the films were deposited at 240 0C in every case, save for the use of different concentrations of LOPs (~0.025 to 4%) in solution.
The surface morphology and the root mean square surface roughness for PS thin films were determined by Atomic Force Microscopy, By UV-Vis technique, %T was measured. In addition, infrared spectra, Scanning Electron Microscopy images and EDS chemical composition results are also shown.
Acknowledgments:
The authors would like to thank SECITI (before ICyTDF) project PICSO12-119, and CONACyT México because of financial support.
[1] S. Carmona-Téllez et.al., White light emitting transparent double layer stack of Al2O3 :Eu3+, Tb3+, and Ce3+ films deposited by spray pyrolysis, ECS Journal of Solid State Science and Technology, 2 (6) (2013)
[2] A. E. Esperanza-García et. al. Luminescent and Morphological characteristics of Al2O3:Tb films deposited by spray pyrolysis using acetylacetonates as precursors. Journal of the electrochemical society, 150 (2) H53-h56 (2003)
Development of a Silver/Silver Ibuprofenate Potentiometric Sensor for Ibuprofen Quantification in Pharmaceutical Products
Authors: Rivera-Hernández Selene Irisais , Álvarez-Romero Giaan Arturo , Galán-Vidal Carlos Andrés , Páez-Hernández María Elena , Corona-Avendaño Silvia 
Published: February 2020

Nonsteroideal antiinflamatory drugs (NSAIDs) are the most used drugs due to their analgesic, antipyretic and antiinflamatory properties, along with the fact that these are sold without the requirement of a medical prescription. Within this group of pharmaceutical compounds, ibuprofen (acid-α-methyl-4(isobutyl)-phenylacetic) is found. The use of Ibuprofen has increased because it is useful for treating headaches and arthritis. It is considered a safe drug since the human body can degrade it to its main metabolites and then excrete them through urine.
Nevertheless, to assure consumer’s health, it is necessary the development of analytical methodologies to allow an accurate and exact quantification of ibuprofen. Potentiometry has demonstrated to be an advantageous technique, where stands out the use of second type electrodes, which in accordance with the Nernst equation can detected anions activities.
Considering this last, in this work we present the development and analytical characterization of a second-type electrode based on the Silver/Silver Ibuprofenate (Ag/AgIbu) pair.
A pure silver wire was modified using a 0.05 M sodium ibuprofenate solution and 0.1 M of sodium nitrate as supporting electrolyte. Chronoamperometry was used to achieve the modification of the electrode (Ag/AgIbu), the technique parameters were optimized and the registered optimums where: 0.8 V (vs Ag/AgCl) potential for 30 s. Calibration curves were performed to obtain the best analytical parameters: it was registered a sensitivity of -41.69 ± 1.61 mV/log (ibuprofenate molar activity), a linear range of 1.22x10-4 - 8.98 x 10-3 M, and a detection limit of 8.11x10-5 M. Repeatability interpreted as the relative error percentage, was 2.46%. The pH effect on the system response was studied, it was found that the best working pH is 7.0. The electrode’s time response was 3.3 min with a drift of -0.01 mV s-1. With the Matched Potential Method it was possible to determine that chloride and carbonate are the most important interferents.
Ibuprofen was measured in commercial drugs with no significant differences found between the manufacture’s reported value and the one obtained with the proposed sensor.
The Study of Electrodeposition of Si in Tmhatfsi-SiCl4 analyzed by EQCM Method
Authors: Tsuyuki Yasuhiro , Pham Anh Huynh Tram , Komadina Jason , Fukunaka Yasuhiro , Homma Takayuki 
Published: February 2020

An inexpensive fabrication method of Si is required for achieving Ultra-Large-Scale Si solar power generation. Electrodeposition method has attracted recently because it has numbers of advantages such as simplicity of process and precision control of reaction etc. compared with conventional methods such as CVD, sputtering and e-beam evaporation.
Si electrodeposition has been conducted using nonaqueous solvents (molten solt1), organic solvent2) and ionic liquid3)) because the reduction potential of SiO2 is very negative. However, the organic solvents have a drawback due to safety concerns, with high flammability. On the other hand, ionic liquids (sometimes referred as room temperature molten salts) exhibit low volatility and in many cases are nonflammable. The primary benefit of both systems is the large electrochemical window, allowing for study of elements such as Si and Li. We have reported the electrodeposition of Si from an ionic liquid.4)

However, high purity Si electrodeposition has not been demonstrated yet. Si electrodeposition layers include some impurities stemmed from ionic liquids.5) It is caused by the uncertainty on Si electrochemical reaction mechanism.
Electrochemical quartz microbalance (EQCM) impedance method could provide us to obtain in-situ information about the mass change during electrodeposition. Such information might further support our deduction on electrochemical reaction mechanism.
Here we present the results of our recent work on the analysis of Si electrodeposition using EQCM method. Si is electrodeposited at 40 °C in an ionic liquid, specifically tri-methylhexyl ammonium bis-(trifluorosulfonyl) imide (TMHATFSI). In particular, we focus on the mass change during cyclicvoltammogram and chronoamperometry. Figure1 demonstrates that Si deposition starts around -2.2 V because a significant mass increase is observed with the increase of the current density. It corresponds to our previous study.5) Therefore we could propose Si electrochemical reaction mechanism more clearly than before from this EQCM result.
This study was financially supported in part by CREST program by Japan Science and Technology Agency (JST).
1). Y. Nishimura, Y. Fukunaka, T. Nishida, T. Nohira, and R. Hagiwara. Electrochem. Solid State Lett. 11 (9) D75-79 (2008)
2). Y. Nishimura and Y. Fukunaka. Electrochim. Acta. 53, 111-116 (2007)
3). F. Endres, A.P. Abbott, and D.R. MacFarlane. Electrodeposition from Ionic Liquids. Wiley-VCH. 2008.
4). T. Homma, J. Komadina, Y. Nakano, T. Ouchi, T. Akiyoshi, Y. Ishibashi, Y. Nishimura, T. Nishida, Y. Fukunaka, Electrochem. Soc. Trans., submitted.
5). J. Komadina, T. Akiyoshi, Y. Ishibashi, Y. Fukunaka, T.Homma. Electrochim.Acta, 100, 236-241 (2013)
Electrocatalytic Activity and Stability of Supported Palladium Nanoparticles
Authors: Ju Wenbo , Brülle Tine , Favaro Marco , Agnoli Stefano , Granozzi Gaetano , Schneider Oliver , Stimming Ulrich 
Published: February 2020

The overall performance of the polymer electrolyte membrane fuel cell (PEMFC) essentially depends on the catalytic activity of its core-part: the membrane electrode assembly (MEA). Palladium (Pd), one of the platinum group elements, is a potential substitute for Pt to be applied as the electrocatalyst, since it has more abundant reserves and a lower price compared to Pt. Pd is stable under extremely corrosive conditions similar to Pt.
Nanosized metal particles perform considerably different as compared to the corresponding bulk materials. Furthermore, some reactions catalyzed by metal particles show a strong particle-size sensitivity. In previous work of our group, particle-size dependent activity of metal particles for electrocatalytic reaction was observed, such as Au nanoparticles supported on HOPG for oxygen reduction reaction (ORR) [1] and Pd nanoislands supported on Au(111) surface for hydrogen evolution reaction (HER) [2]. Beside the particle-size effects, support effects (e.g. ligand effect, strain effect) play important roles on electrocatalytic activity as well [3].
In order to research the particle-size effects and support effects on the activity and stability of Pd nanoparticles, highly oriented pyrolytic graphite (HOPG) and nitrogen doped HOPG (N-HOPG) [4] were used in this work. Due to the weak interaction of HOPG with metal deposits, the substrate-related effects can be eliminated. N-HOPG is rich in electronegative nitrogen functional groups, and the roughness of N-HOPG is much higher than the untreated HOPG before the nitrogen implantation process. Pd nanoparticles were electrochemically deposited by double-pulse electrochemical deposition on both substrates. Pd nanoparticles are located mainly at the defects and step-edges on HOPG surface, but on the N-HOPG particles are distributed homogeneously. For ORR, the smaller particles have a negative particle-size effect. Pd nanoparticles supported on N-HOPG do not show enhanced activity for ORR. For HER, the case is much more difficult for the behavior of hydrogen absorption of Pd. The content of absorbed hydrogen atoms in Pd NPs is influenced by the particle size. The stability of Pd nanoparticles on HOPG is influenced not only by the particle size, but also by the pH value of the electrolyte. Pd particles on N-HOPG show poorer stability as compared to the pure HOPG insofar as they dissolved rapidly in potential cycling measurements.
[1] Brülle, T.; Ju, W.; Niedermayr, P.; Denisenko, A.; Paschos, O.; Schneider, O.; Stimming, U., Molecules 2011, 16 (12), 10059-77.
[2] Pandelov, S.; Stimming, U., Electrochimica Acta 2007, 52 (18), 5548-5555.
[3] T. Bligaard, J.K. Nørskov, Electrochimica Acta, 52 (2007) 5512-5516.
[4] Favaro, M.; Perini, L.; Agnoli, S.; Durante, C.; Granozzi, G.; Gennaro, A., Electrochimica Acta 2013, 88, 477-487.
Study of Corrosion Inhibitors for Mg Alloy AZ31B with Variations of PCO2 and Electrolyte Layer Thickness
Authors: Kaminski Daniel , Buchheit R. 
Published: February 2020

Magnesium alloys have been proven as useful, lightweight, engineering materials in several applications such as aerospace transmission casings and enclosure frames for general consumer electronics. Automotive industry has also shown much interest in this material both in the past and recent years. Yet, the full applicability of magnesium alloys has not yet been achieved due to their active corrosion in common media.
One way to act upon the corrosion of magnesium alloys is by corrosion inhibiting chemical compounds. Such compounds, when effective at low concentrations, are ideal candidates for coatings-based inhibitor systems provided that they can be stored and released by ion-exchange pigment additions to the coating. To date, corrosion inhibitor studies for magnesium alloys have almost entirely relied on techniques based on immersion of specimen in bulk solution.
In the present work, it is shown that the corrosion product and effectiveness of several inorganic inhibitor compounds on AZ31B, such as sodium metavandate, vary with both electrolyte layer thickness and partial pressure of CO2. Characterization of corrosion product layers indicates tendency for the formation of magnesium carbonates rather than Mg(OH)2 (brucite) when specimen are exposed to electrolyte layers as thick as 250µm compared to test conditions of the same CO2 partial pressure in bulk solution. Furthermore, it is shown that in some cases inhibitor compounds exhibit change in speciation with the changing parameters. It is well known that corrosion inhibition by inorganic ions is often particular to oxidation state and speciation of the compound such as is the case for tetrahedral coordinated vanadate species. Hence corrosion inhibitor effectiveness is altered by accessibility of CO2 and electrolyte layer thickness.
Lastly, synergistic effects of exposure cnditions with corrosion inhibitor compounds is discussed and examples given. These conclusions highlight the importance of replication of likely field exposure environment in design of lab experiments for magnesium alloys. Such information is crucial to the future development of coatings-based inhibitor systems.
Quantitative Characterization of SEIs and Lithiation/Delithiation Processes in Electrolytes with Additives Using In Situ Electrochemical Quartz Crystal Microbalance-Dissipation (EQCM-D)
Authors: Yang Zhenzhen , Trahey Lynn , Thackeray Michael M. 
Published: February 2020

In recent years, the crucial role of solid electrolyte interphases (SEIs) in Li-ion batteries (LIBs) has been well recognized by extensive studies. In spite of all available information, there are still issues relevant to the SEI formation, composition, and mechanical properties that have to be addressed. We have recently utilized Electrochemical Quartz Crystal Microbalance with Dissipation (EQCM-D) to study how SEI develops on tin thin film electrodes and probed the mass gain/loss in electrolytes with different amounts of fluoroethylene carbonate (FEC) additives upon electrochemical cycling. As shown in Figure 1, the detailed processes of the decomposition of the electrolyte on the electrode surface and Li alloying/dealloying with Sn were characterized quantitatively by measuring the decrease/increase of the resonance frequency in the cell. The effects of FEC on SEI formation and lithiation/delithiation cycles are also carefully studied and presented. The results suggest that varying the concentration of FEC is important for adjusting the SEI mass and thickness on the anodes.
The key points of employing EQCM-D in this work are the extension of measurements to higher harmonics and incorporation of dissipation (D). The capabilities enable the detection of the properties of interfacial films such as rigidity and viscoelasticity. The final modeling results from EQCM-D demonstrate that the SEI layer is dynamically shifting in the mass, thickness and viscoelastic properties during every cycle. Therefore, given the unique advantage of EQCM-D, it is expected that the full picture of SEI formation, including mechanic properties and compositional change, can be reflected.
In-Depth Investigation on Electrochemical Behaviors of Next Generation Cathode Materials for Lithium-Ion Batteries
Authors: Kim Young Jin , Shi Zhong , Sheargold Stephen 
Published: February 2020

The transportation landscape is changing and vehicle electrification continues to gain traction in the market. The trend towards electric mobility (e-mobility) has shown a significant rise in recent years along with advances in technology and government subsidies, but there is still a long way to go for the future of e-mobility to be realized. The heart of e-mobility is the battery and its performance is fundamental to the success of e-mobility.
The cathode has a large stake in the key characteristics of the battery, such as energy density, power capability, safety, and cost. Advancements of cathode materials directly result in the improved battery performance with higher significance. BASF has focused on the development of next generation cathode materials (high energy Li-Mn-rich NCM and high voltage spinel) as well as advanced surface modification techniques.
In this presentation, we will report the electrochemical behaviors of a few of our latest cathode materials for advanced lithium-ion batteries. Three-electrode cell testing results will reveal in-depth information regarding early stage electrochemical formation process as well as cycling performance. Subsequently performed post-mortem investigation will provide analysis of capacity fade and failure mechanism during/after cycling procedure. Also, insights on the path forwards to further improve battery performance will be shared.
Effect of Metal Composition on the Electrochemical Properties of Lithium-Rich Positive Electrode Materials
Authors: Shunmugasundaram Ramesh , Dahn Jeff 
Published: February 2020

Introduction

Lithium-rich mixed transition metal (TM) oxide positive electrode materials such as Li[Li0.2Ni0.2Mn0.6]O2 and Li[Li0.2Mn0.54Ni0.13Co0.13]O2 are attractive due to their high reversible capacities. However, they suffer from some problems such as high irreversible capacity loss1, poor rate capability2 and voltage fade3. There is no clear understanding in the literature how the overall metal composition of the Li-rich material affects their electrochemical properties including the above mentioned issues. Hence we embark, in this study, on studying the effect of metal composition on the electrochemical properties of the Li-rich positive electrode materials.

Experiment

A series of Ni(II)aMn(II)bCo(II)cCO3 precursors where a + b + c = 1 were made with co-precipitation synthesis using a continuously-stirring tank reactor (CSTR). Ni(II)aMn(II)bCo(II)cCO3 precursors were mixed with required amounts of Li2CO3and made into Li-rich positive electrode materials of the desired composition using solid-state synthesis at 900ᵒC in air. All the prepared materials were characterized by X-ray diffraction and their true densities were measured using a helium pycnometer. Coin-type cells were made from the synthesized positive electrode materials and Li metal anodes, which were then electrochemically tested under galvanostatic conditions at constant temperature, and their electrochemical properties were compared.

Results and Discussion

A Li-rich positive electrode material comprised of Li, Ni2+, Mn4+ and Co3+ can be made from a Ni(II)aMn(II)bCo(II)cCO3 precursor. By knowing the exact composition of Ni(II)aMn(II)bCo(II)cCO3 precursor, the theoretical formula of a Li-rich material can be calculated. For example, the Ni0.25Mn0.75 composition can be used to make Li1.2Ni0.2Mn0.6O2. Thus, the Ni-Mn-Co compositions that can be used to make all the possible Li-rich positive electrode materials were determined. Details results showing how the electrochemical behavior varies with overall metal composition will be presented.

References

1. J. H. Kim, C. W. Park, and Y. K. Sun, Solid State Ionics, 164, 43 (2003).
2. B. Xu , C. R. Fell , M. Chi , Y. S. Meng, Energy Environ. Sci.2011, 4 , 2223
3. Debasish Mohanty, Athena S. Sefat, Jianlin Li, Roberta A. Meisner, Adam J. Rondinone, E. Andrew Payzant, Daniel P. Abraham, David L. Wood, Claus Daniel, Phys.Chem.Chem.Phys., 2013, 15, 19496--19509
Li3V2(PO4)3 As a Positive Electrode Material for Rechargeable Lithium Batteries
Authors: Park Jae Sang , Myung Seung-Taek 
Published: February 2020

Nowadays, demands lithium ion batteries which are mounted in portable devices increase day by day. As a result, research towards positive and negative electrode materials being intensively progressed.
Most commonly used positive electrode is LiCoO2 because it has good electrochemical property. However, Co is rare material and it is placed in limited area. Therefore, price of Co increases more and more. To substitute Co, plenty of transition metal material is studied such as Fe, Ni, Mn and V. Among them polyanion phosphate material such as LiMPO4 (M = Fe, Co, Mn and etc) and Li3V2(PO4)3 are considered as possible candidate materials because of their structure, thermal stabilities and low price. However, those polyanion material, LiMPO4 (M = Fe, Co, Mn) has low energy density, causing low energy density. Li3V2(PO4)3 has good safety as LiFePO4 but higher energy density than LiFePO4 because of its high redox potential, V2+/5+. Also, Li3V2(PO4)3 has high reversible capacity and high theoretical capacity (197 mAh g-1). In this paper, physical and electrochemical properties of Li3V2(PO4)3 is investigated.
Li3V2(PO4)3 is synthesized by solid state method. Stoichiometric amount of Li2CO3, NH4H2PO4, and V2O5 powders were grind and mixed by ball mill. The mixed powders were calcined at 500 oC in air atmosphere. The calcined powders were pelletized and sintered at 800 oC for 5 h in reduction atmosphere again. The calcinations, heated pellets were grind in Ar filled glove box to avoid air exposure. The synthesized Li3V2(PO4)3 powders were identified by X-ray diffraction (XRD) with Cu Kα radiation and analyzed by Rietveld refinement. Electrochemical test were carried out in coin type cell. Galvanostatic electrochemical charge and discharge test were made between 3.0 V and 4.8 V at 10 mA g-1 current at room temperature.
The XRD pattern of the product shows single phase Li3V2(PO4)3 were obtained without impurity. The galvanostatic charge and discharge performances of Li3V2(PO4)3 as an positive electrode are tested in voltage range of 3.0 V and 4.8 V. Also to understand the mechanism during charge and discharge, ex-situ XRD, XPS and ToF-SIMS measurement were carried out at the first cycle. Furthermore to understand the affect the thermal stability high temperature XRD and TGA were carried out. Details will be discussed in the conference site.