bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zinc Phosphate Glasses Doped Yttrium-Europium Oxide, a Luminescence Study
Authors: Mariscal B. L. , Carmona-Tellez S. , Murrieta H. , Falcony Ciro , Rivera-Álvarez Zacarias 
Published: February 2020

Zinc phosphate glasses doped with yttrium-europium oxide, were obtained by melting at 1100 °C; suitable precursors of these glasses quantities was grinded mechanically and dried at 400 °C for 2hrs, then the temperature was raised to 800 °C for 2hrs again, finally the temperature was raised at 1100 °C for 3hrs until a liquid is achieved, this liquid is emptied in a copper block to produce a thermal shock and observe the formation of a glass; a final heat treatment at 300°C for 12hrs is practiced.
Luminescent studies were conducted in these glasses, it is observable, that when excited with λexc = 396nm are present the 5D0 to 7F1, 7F2, 7F3 y 7F4 transitions in 590, 616, 650, and 697 nm; the main emission is achieved at 616 nm and a high red light emission is observable at naked eye, due to the presence of europium ions. Absorption spectra, transmission and reflectance are obtained; these glasses are transparent in the region of 400 nm to 1100 nm UV; XRD indicates that samples are amorphous; the emission spectra of these glasses were doped with different amounts of yttrium-europium oxide; they depend on the amount of dopant.
The luminescent properties of Y2O3:Eu3+ powders have been studied, luminescent Y2O3:Eu3+ polycrystalline powders were synthesized by a simple evaporation method. The photoluminescence and cathodoluminescence emission spectra these samples show, luminescence peaks associated with transitions within the electronic energy levels of Eu3+ ions. The dominant peak is at 612nm corresponding to the 5D0 to 7F2 transition and present 5D0 to 7F1, 7F2, 7F3 y 7F4 transitions in 590, 616, 650, and 697 nm, when excited with λexc = 260 nm and λexc= 396at room temperature. The intensity luminescence Y2O3:Eu3+ powders with different dopant concentrations, Eu3+ ion dependent percentage, finding the optimal concentration is 17 mol%.
XRD of powders Y2O3:Eu3+ show these correspond to space group: Ia-3(206), with Cell: 10.6039 10.6039 10.6039 90.000 90.000 90.000, Volume: 1192.328 and whit Crystal System: Cubic (No: 01-075-3096); these powders were evaporated at 200 °C and then calcined for two hours at 1100°C. EDS analysis shows that the corresponding Y2O3:Eu3+ powders, showing that the achieved yttrium is stoichiometric according to general Y2O3 formula. According to the results of the photoluminescence of these powders Y2O3: Eu3+, to excite λexc = 396nm have the energy required for luminescence is less and therefore can obtain low-cost LEDs for red light; so it can be considered that this type of compound is a good candidate to have red light and its preparation is simple and inexpensive.
Radiation Dose Response of Ag-Doped Phosphate Glasses with Different Alkali Metal Compositions in the Host
Authors: Tanaka Hironori , Fujimoto Yutaka , Koshimizu Masanori , Yanagida Takayuki , Saeki Keiichiro , Asai Keisuke 
Published: February 2020

Introduction
For many years, the radiophotoluminescence (RPL) of Ag-doped phosphate glass has been exploited in personal dosimeters. On exposure to X-ray, gamma ray, and high-intensity laser irradiations, the electrons and holes are captured by the Ag+ ions in the glass structure, thereby changing the Ag+ ions into Ag0 and Ag2+, respectively [1]. Thus, Ag-doped phosphate glasses enable the estimation of the exposure dose due to the correlation between the amount of irradiation and the relative intensity of luminescence of the Ag0 and Ag2+ ions excited with ultraviolet light. In a previous research, we found that the peak wavelengths of the RPL bands depend on the alkali metal species used [2]. In this study, we investigated the radiation dose response of various Ag-doped phosphate glasses, containing alkali metals as cations, to optimize their composition and develop a higher-performance dosimeter.
Experimental Methods
The glass samples were prepared according to a conventional melt-quenching method in air. The raw materials, AgCl and (LiPO3)n (Li/Ag), were mixed, loaded into an alumina crucible and melted at 1073 K, for 30 min, in an electric furnace. The melt was then quenched on a stainless steel plate at 573 K, which is below the glass transition temperature. The same operations were also performed for NaPO3 (Na/Ag), (KPO3)n (K/Ag)，RbH2PO4 (Rb/Ag)and CsH2PO4 (Cs/Ag) instead of LiPO3. The Ag concentration was 0.1 mol% for all samples. In addition, phosphate glasses with mixed alkali metals were prepared in the same manner Li/Na-Ag, K/Na-Ag, Rb/Na-Ag, and Cs/Na-Ag.
The samples were irradiated at room temperature with X-rays using an X-ray tube operating at 40 mA and 40 kV. The PL (photoluminescence) and RPL properties were analyzed using both PL and RPL spectra and the temporal luminescence profiles. The PL and RPL spectra were collected using an F-7000 (Hitachi) fluorescence spectrometer. The temporal profiles were recorded using a DeltaFlex 3000U-TMK2 (Horiba). The absorption spectra were measured using a spectrophotometer (Hitachi U-3500).
Results
The RPL spectra of the various Ag- doped phosphate glasses, irradiated with a dose of 50-Gy X-rays, are shown in Fig. 1. The sample K/ Na-Ag shows two emission band peaks, observed at 550 nm and 680 nm, with excitation at 310 nm. The peak of K is also detected at 550 nm with a line shapesimilar to that of the sample K/Ag. On the other hand, the peak of K/ Na-Ag observed at 680 nm shows a line shape similar to that of Na/Ag . These results indicate that Na-K/Ag is composed of K/Ag and Na/Ag domains and that Na and K phosphate layers are separately formed around fluorescent centers.
References
[1] Y. Miyamoto, et al, Radiation Measurements 45 (2010) 546-549.
[2] H.Tanaka, et al, Sensors and Materials (Submitted)

Figure 1
Radioluminescence Properties of Europium Doped Strontium Aluminum Borate Glass
Authors: Kawaguchi Noriaki , Okada Go , Yanagida Takayuki 
Published: February 2020

Recent topics of scintillation materials were development of halide single crystals which exhibit high energy resolution such as divalent Eu doped strontium iodide and novel solid neutron scintillators which contains high efficiency luminescent centers and Li-6 or B-10 ions which convert neutron to charged particles. One of the most traditional neutron scintillator is Ce doped Li silicate glass. On the other hand, Eu doped glass scintillators were not almost studied.
We studied radioluminescence properties of Eu doped strontium aluminum borate glass (Eu 0.1% : 35 SrO – 15 Al2O3 – 50 B2O3) in order to obtain divalent Eu doped borate glass. As a result of X-ray excited luminescence, emission peaks were observed around 600 nm; they are originated from trivalent Eu. Emission peak was also observed around 400 nm; it might be originated from defect or divalent Eu. Detail of X-ray excited luminescence around 400 nm and Eu doping concentration dependence of radioluminescence spectra will be discussed on the conference.
Novel Measurement Technique for Time Dependant Intensity Variations of AC-LEDs
Authors: Korte Simon Dominik , Juestel Thomas 
Published: February 2020

LEDs have surpassed incandescent and compact florescent lamps for general lighting during the last 10 years.1 Nowadays, they show very high wall plug efficiency while providing a good colour rendering index (CRI). However, flicker is still a perceivable drawback to these light sources.2 The impact and perception of flicker is increasingly investigated and its consequences for human beings range from headaches over migraines to severe neurological problems, including epileptic seizure.3 Evaluating these effects requires a number of factors to be taken into account, for instance duration of exposure, stimulated area of the retina and brightness and colour of the flickering LED source. Flicker is defined as “the rapid variation in light source intensity”.4 To describe the flicker of a light source, two metrics are currently used, flicker percentage and flicker index. Both are mathematical approaches which use the overall emission intensity and compare the minimum and the maximum intensity within a single cycle or curve integrals to gain a key figure. They do not take the wavelength, the frequency, or the duty cycle into account. The presented, novel measurement technique processes the spectrally resolved emission intensity during an adjustable amount of duty cycles, shapes and frequencies. In order to verify this measurement technique, standard phosphors such as Y3Al5O12:Ce3+ (YAG:Ce), BaMgAl10O17:Eu2+,Mn2+(BAM:Eu,Mn) have been investigated with a rectangular pulsed 50 or 100 Hz LED as excitation source. YAG:Ce showed strong flicker while BAM:Eu,Mn exhibits a flicker reducing effect. The spectrally resolved measurement technique allows us to correlate the measurement data with the eye sensitivity curve resulting in a new kind of flicker index.
References

1.
M. Krames, O. Sheckekin, R. Mueller-Mach, G. Mueller, L. Zhou, G. Habers and M. Craford, “Status and Future of High-Power Light-Emitting Diodes for Solid-State Lighting,” J. Disp.
Technol.
3, (2) 160 (2007).

2.
J. Tan and N. Narendran, “Defining Phosphor Luminescence Property Requirements for White AC LED Flicker Reduction,” J. Lumin.
167, 21 (2015).

3.
A. Wilkins, J. Veitch and B. Lehman, LED Lighting Flicker and Potential Health Concerns: IEEE Standard PAR1789 Update, 2010.

4.
M. Rea, IESNA Lighting Handbook, New York: Publication Department IESNA, 2000.
(Invited) Thermal Quenching of Phosphors: How to Reduce/Remove It?
Authors: Im Won Bin , Kim Yoon Hwa 
Published: February 2020

The most significant revolution in artificial lighting is prompted by the work of 2014 Nobel laureates who developed efficient blue light-emitting diodes enabling bright and energy saving phosphor-converted white light-emitting diodes (pc-WLEDs). However, the most critical property is the thermal stability of phosphors, since, in general, emission losses occur during LED operation due to heat generation (~200˚C), which is detrimental to pc-WLEDs and this process is known as thermal quenching (TQ).
In this talk, different techniques have been employed to enhance the thermal stability of phosphor, such as making solid-solution of phosphors, applying ceramic coatings onto phosphor surfaces, and glass ceramic phosphor. Also we report the first of the self-healing blue phosphor that does not exhibit TQ, and sustains its emission intensity up to 200°C.
Optimization of Enzyme-Reconstituted Electrodes in Enzymatic Biofuel Cell for Low Power Applications
Authors: Parmar Sarthak , Durga Siddarth , Amaravati Sivakumar , Chittur Krishnaswamy Subramaniam 
Published: February 2020

An enzymatic biofuel cell uses enzymes as a catalyst to oxidize its fuel, instead of precious metals like Platinum as in a conventional hydrogen fuel cell. Here to generate electricity chemical energy stored say in glucose is converted into electricity. Enzymatic oxidation from complex sugar is carried out by glucose selective enzymes such as gluco oxidase (Gox) and oxygen reducing enzyme namely laccase. These reactions are highly enzyme specific and occur at relatively mild conditions (Neutral pH and ambient temperature). It is necessary to thus to fabricate enzyme reconstituted electrode for the Membrane Electrode Assemble (MEA). The cell features (i) a 3-D meso/micro porous carbon electrode, for high surface area (ii) Cellophane paper, to immobilize the enzyme and mediators used (ferrocene) (iii) Perfluro sulphonic acid membrane to separate the potential developed between the enzymatic activity and the electron acceptor and to facilitate ion transfer (iv) Perspex glass cell structure (v) Copper micro mesh, as current collectors.
The electrochemical characteristics of MFC are studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) fluorescence imaging and polarization profiles. The achievable power density is still below theoretical value. A cell potential of around 0.7 to 0.8V is targeted.
Complete the characterisation and optimisation in terms of enzyme loading capability, conductive loss both electronic and ionic, direct charge transfer for improving charge transfer efficiency, and pore channel and size profile of the enzymatic cells, will be presented.
Low power applications like implantable devices (pacemakers) and other medical devices will be studied.
Exploring Selective, Efficient 2 e- and 4 e- Electrochemical Oxygen Reduction Using Electrocatlayts Based on Reduced Graphene Oxide
Authors: Kim Hyo Won , McCloskey Bryan D 
Published: February 2020

Recently, nitrogen-doped carbon materials, such as N-doped reduced graphene oxide (N-rGO), have been significantly studied due to their outstanding ORR performance, which some studies find rivals that of Pt. Generally the electroreduction of oxygen can proceed through one of two overall reactions: a 4e- process to convert from O2 to H2O, and a 2e- process to form H2O2. There is general agreement that nitrogen-defects selectively catalyze the more thermodynamically favored 4e- mechanism over the 2e-process. However, a distribution of different N-defect sites (pyridinic, pyrollic, graphitic) is typically observed in N-doped carbon materials and there is still no consensus regarding the role of each site on the ORR mechanism.
In this study, we use a straightforward, low temperature and pressure procedure to synthesize N-rGO and rGO and compare the resultant materials’ electrocatalytic behavior with rGO and N-rGO synthesized using more traditional high-temperature procedures. Briefly, the low temperature and pressure synthesis was conducted at 100 oC and atmospheric pressure using NH4OH as both the reducing and N-doping agent in a well-dispersed graphene oxide (GO) solution. This method results in materials with a distribution of the three nitrogen defect sites and reasonably high N-doping content (~6 atomic percent), as confirmed by structural analysis including XPS and TGA. The resulting materials could be further annealed at high temperatures (over 400 oC) under inert condition to modify the nitrogen and carbon defect distribution. Similar synthesis procedures were used to prepare non-N-doped rGO samples to elucidate the importance of N-sites.
We have characterized electrocatalytic selectivity by monitoring O2 pressure decay in well-stirred, modified electrochemical H-cells with a calibrated, known headspace volume. We also quantify H2O2 formation using a standard iodometric titration on the electrolyte. These techniques provide direct measurements of O2 consumption and H2O2 formation during ORR and are therefore more accurate than traditional rotating ring disk electrode measurements. Both acid (0.1 M H2SO4) and base (0.1 M KOH) conditions have been explored. We have found that certain variants of N-rGO and rGO display exceptionally selective (~100%) and efficient (nearly no onset overpotential) formation of H2O2 in basic conditions. Thermal annealing changes both the N-site distribution and reaction selectivity and efficiency. Furthermore, higher overpotentials for product formation are observed in acid solutions compared to basic solutions. Results will be discussed linking the selectivity and efficiency of the oxygen reduction reaction to the role of nitrogen and carbon defects in N-rGO and rGO.
Modification of Microelectrode Surface with Hydrogel Layers and Determination of Pore Size in Layers
Authors: Kaniewska Klaudia , Karbarz Marcin , Hyk Wojciech , Stojek Zbigniew Jan 
Published: February 2020

Hydrogels are three dimensional networks filled with water. Some of the gels can undergo fast, reversible volume phase transition (VPT) in response to a change in environmental conditions. During the transition the gels transform from one state to another (swollen/ shrunken) by changing content of water in the network. Interestingly, the gels have properties of both: solids and liquids. In the macroscopic scale the structure of the network is responsible for the mechanical energy storage. In the microscopic scale the gels exhibit the properties of water: their density is similar and diffusion processes occur in the network [1].
Pores and channels of nanometer size are employed to separate the analytes by size and to control their transport. The size of the pores could be easily changed in the hydrogel matrix by involving the shrinking and swelling process especially in the gels with continuous volume phase transition.
The main aim of this paper was to develop an electrochemical method of obtaining the NIPA- and NIPA-co-AA hydrogel films on the microelectrode surface without previous surface functionalization. Another aim was to determine the size of pores/channels in NIPA- and NIPA-co-%AA gels and to evaluate porosity of the gels. The hydrogel films were anchored to the microelectrode surface via electrochemically induced free radical polymerization (EIFRP) process with utilizing the chronoamperometric method. We found that cyclic voltammetry could be also successfully applied to obtain thin hydrogel layers. The electrochemical studies of the discontinuous volume phase transition and the determination of the channel size were done using the ferrocene molecules modified with polyethylene glycol units (PEG) of various length.

Figure 1. Woltamperograms obtained during the electrochemically induced free radical polymerization on platinum microelectrode This work was supported by a grant from the National Science Centre of Poland, Preludium 8, 2014/15/ST5/01980

[1] A. B. Imran, T. Seki, Y. Takeok, Polymer Journal, 2010, 42, 839–851

Figure 1
Electrocatalytic Alcohol Oxidation By a Ruthenium-Modified Covalent Triazine Framework
Authors: Yamaguchi Shingi , Kamiya Kazuhide , Nakanishi Shuji , Hashimoto Kazuhito 
Published: February 2020

Ruthenium (Ru) based catalysts, such as RuO2 and Ru complexes, have been widely studied for various oxidation reactions, such as oxygen evolution reaction (OER) and alcohol oxidation reactions (AOR). For example, RuO2 is an efficient anode catalyst for OER, which is a key reaction for artificial photosynthesis. However, as OER competes with AOR under the range of operating potentials, the high activity of RuO2 for OER results in the low Faradaic efficiency for AOR. In contrast, some Ru complexes are known to catalyze AOR with high efficiency [1]. However, as these Ru complexes are homogeneous catalysts, they are fragile and are difficult to separate and recycle.
Recently, we have focused on covalent triazine frameworks (CTFs) as heterogeneous electrocatalysts. CTFs have 1,3,5-triazine units as linkers, and are representative microporous conjugated polymers. As CTFs possess abundant nitrogen (N) atoms with electron lone pair for metal coordination, CTFs are expected to stabilize Ru atoms through coordination with the N atoms like Ru complexes. Recently, we have indeed synthesized single-Pt atoms modified CTF hybridized with conductive carbon nanoparticles (Pt-CTF) as an electrocatalyst [2]. The Pt-CTF catalyzed the oxygen reduction with a high methanol tolerance, a unique property that was attributed to the atomic dispersion of Pt. In the present work, we successfully synthesized a Ru-modified CTF (Ru-CTF; Figure) and examined the electrochemical alcohol oxidation activity of this novel material. The Ru-CTF effectively oxidized alcohol with low OER activity.
[1] TJ Meyer, M. Huynh, Inorganic chemistry,
2003, DOI 10.1021/ic020731v.
[2] K. Kamiya, et al, Nat. Comm. 2014, 5, 5040.

Figure 1
Application of Electrochemically Deposited Cobalt Films in a Hydrogen Evolution Reaction
Authors: Abdel-Fattah Tarek M , Huff Clay , Dushatinski Thomas 
Published: February 2020

Hydrogen gas production is a rapidly growing field of research due to its desirable properties from a sustainability viewpoint. The burning of hydrogen gas provides an environmental incentive as well, due to the lack of carbon-based byproducts [1-2]. Hydrogen gas is often evolved from water but is an energy intensive process. Solid chemical storage has been implemented through the use of metal hydrides, such as sodium borohydride. The oxidation reaction of sodium borohydride in water slowly evolves 4 moles of hydrogen gas. While a slow reaction is favorable for reduction, the use of NaBH4to produce hydrogen gas necessitates the use of catalysis to accelerate the reaction to an appreciable rate. A great deal of research has been conducted searching for catalysts of such reactions, often finding noble metals to be the most efficient. While less efficient than noble metals, cobalt materials have also demonstrated catalytic properties in a variety of hydrogen evolution reactions. Cobalt is more abundant in the earth’s crust than the noble metals, which makes it an arguably more attractive catalytic material due to a relatively lower cost and easier scalability [3-5].
Cobalt films deposited from aqueous (H2O/CoCl) and non-aqueous precursor (Ch:Ch/EG/CoCl) solutions were tested for catalytic activity in the hydrogen evolution reaction of aqueous NaBH4. The evolved gas was measured through the use of a water-displacement system, Ohaus microbalance, and mass logging software. The non-aqueously deposited films initially showed a higher reaction rate, but voids in the surface could prevent disassociation of the hydrogen, reducing the catalytic surface. The aqueously deposited films were largely amorphous, providing better active sites for the reaction than its non-aqueous counterpart. Both Co films outperformed the copper substrate (Cu).

Catalytic Surface

Rate Constant (10-3 min-1)

Aqueous Co Deposition
4.9

Non-aqueous Co Deposition
4.6

Original Copper Substrate
3.3

References:

Schlesinger, H.; Brown, H.; Finholt, A.; Gilbreath, J.; Hoekstra, H.; Hyde, E. Sodium Borohydride, Its Hydrolysis and its Use as a Reducing Agent and in the Generation of Hydrogen. 1952,
J. Am. Chem. Soc. 75(1) 215-219

Chinnappan, A.; Kang, H.; Kim, H. Preparation of PVDF nanofiber composites for hydrogen generationfrom sodium borohydride. 2011,
Energy 36(2) 755-759

Dushatinski, T.; Huff, C.; Abdel-Fattah, T. Synthesis and Characterizations of Cobalt Films Electrochemically Deposited from Aqueous and Non-Aqueous Media. 2014,
ECS Trans. 64(4) 487-491

Dushatinski, T.; Huff, C.; Abdel-Fattah, T. Optical Properties of Cobalt Films Electrochemically Deposited from Aqueous and Non-Aqueous Ionic Liquids. 2014,
ECS Trans. 61(10) 43-46

5. Damiano, B.; Wixtrom, A.; Abdel-Fattah, T. Electrochemical Deposition of Cobalt onto the Surface of Copper Using a Choline Chloride-Based Ionic Liquid.2012,

ECS Trans.
50(11) 277-281