bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intermediate Temperature - SOFCs: Nanoparticles Synthesis through Coprecipitation By Nitrate Route and By Oxide Route
Authors: Ribadeneira Paz Rafael Esteban , González Ocampo Javier 
Published: February 2020

Solid Oxide Fuel Cells (SOFCs) are very promising devices to generate electrical energy for stationary applications as auxiliary power units for several purposes such as electrical grids, smart grids, cogeneration in different industrial processes, and also for transport, using mainly hydrogen and alternative fuels as syngas with high H2 - content. Additionally the SOFCs have the advantage of a high efficiency considering cogeneration (80-93%) and also this technology produces minimal pollutant emissions.
Despite of enormous progresses made to date, this technology has to reach all technical requirements in order to be competitive. In this sense, the SOFCs must operate at intermediate temperatures (450 – 650 °C) instead high temperatures (around 1000°C). To reach this objective the research of the chemical routes to synthesize the catalysts for anode and cathode, and also the electrolyte is a key step to achieve the best electrochemical behavior of SOFCs operating at intermediate temperatures.
The electrochemical and mechanical properties of anode, cathode and electrolyte oxides for SOFCs are primordially determined by the chemical synthesis route. In this work a comparison between two coprecipitation routes is presented using: i) nitrates and ii) oxides. These synthesis routes were tested for the anode (nickel oxide – NiO), the cathode (lanthanum strontium cobalt ferrite - LSCF) and the electrolyte (gadolinium and samarium doped ceria – GDC and SDC, respectively).
For these four compounds (NiO, LSCF, GDC and SDC) the physical characterization consisted in SEM – morphology analysis. Also the crystal structure and the nanoparticle size is determined by X-ray diffraction (XRD). The chemical characterization is carried out using energy-dispersive analysis (EDS). In addition to the physical and chemical characterization a symmetrical two-electrode electrochemical test cell is tested in the range of intermediate temperatures (450 – 650 °C).
These two routes of synthesis by coprecipitation are compared determining the most suitable and economical method to produce anodic, cathodic and electrolytic powders oriented to a better electrochemical behavior for intermediate-temperature solid oxide fuel cells (IT-SOFCs).
Low Temperature Methane Steam Reforming for SOFC
Authors: Sun Jie , Li Ji Gang , Zhu Yue Feng , Zhang Jing Jing , Zhou Tian , Li Li , Wang Yu Guang , Liu Shuai , Jiang Zhi Gang , Dong Zhong Chao , Sun Chun Wen , Li Hong , Chen Li Quan 
Published: February 2020

The properties of flowerlike microspheres ceria based nickel catalyst for low temperature methane steam reforming were studied. The ceria microspheres were prepared by hydrothermal method. Catalyst of nano-sized nickel oxide particles based on flowerlike cerium oxide microspheres with high disperse were prepared to achieve simultaneous dehydrogenation of methane and water molecules on multi-active sites. The catalyst was characterized by means of Scanning Electronic Microscope (SEM), X-ray diffraction (XRD). Results showed that this special catalyst NiO/CeO2 had high activity and stability for methane steam reforming reaction below 600oC, improve the resistance of carbon deposition catalyst greatly. The stability of the catalyst was reached more than 1000 hours. The conversation of methane under 590oC was above 90%. The tests of the influence of different steam to carbon ratios on activity and selectivity of catalyst showed that 1.5~2.5 steam to carbon ratio was an ideal choice.
During the running of micro-tube methane steam reformer with this catalyst, the methane conversion of 555oC kept over 25mol.%, the selectivity of H2, CO, CH4 and CO2was 60 mol.%, 10 mol.%, 12 mol.% and 18 mol.%B
(This work was supported by National Key Basic Research Plan (973), No.2012CB215402 )

Figure 1
Carbon Tolerant Electrodes for SOFC and Reversible SOFC (RSOFC) Cells Operating on Carbon Containing Fuels
Authors: Niakolas Dimitrios K. , Neofytides Charalampos , Neophytides Stylianos G. , Tsiplakides Dimitrios , Papazisi Kalliopi-Maria , Balomenou Stella 
Published: February 2020

Solid Oxide Fuel Cells (SOFC) and Electrolyzers (SOEC) hold great potential for the security of energy sector, providing solutions for efficient power generation and production of hydrogen and synthesis gas. A challenging barrier for the successful implementation of SOFC and SOEC technologies, remains the long term stability under realistic operating conditions by the effective control and minimization of degradation due to carbon built up. The problem arise from the fact that the commonly used anode cermets, e.g. Ni-YSZ and Ni-GDC, are prone to carbon deposition onto nickel, as a result of the Boudouard reaction (CH4cracking, disproportionation of CO), leading to low activity and fast degradation.
In this study, a class of Au-modified commercially available NiO/GDC and NiO/YSZ cermet powders has been developed and studied for their performance and tolerance to carbon deposition, operating as SOFC anodes for CH4 steam reforming, as well as bi-functional electrodes in a Regenerative SOFC operating on the CO2 cycle (SOEC mode: electrolysis of CO2, SOFC mode: electrochemical reaction of CO and oxygen for power generation). In- situ HT-XRD tests revealed that the presence of Au, in an optimum nominal loading of 3wt%, affects the Ni crystal phase and has a significant positive effect in inhibiting carbon deposition. The results from cell testing in the temperature range of 800-1000°C, showed promising, stable performance of electrodes under carbon forming conditions (e.g. H2O/CH4=0.25, CO or CO/CO2mixtures of 0.7/0.3).
The work is supported by the FCHJU project T-CELL (298300).
Effects of Current Collector Materials on Performances of Micro-Tubular Solid Oxide Electrolysers for Splitting CO2
Authors: Kleiminger Lisa , Kelsall Geoff H. , Li Tao , Li Kang 
Published: February 2020

As renewable energy sources are inherently intermittent, their increasing contributions to electricity grids will necessitate large-scale energy storage to balance supply and demand. Storing electrical energy in chemical bonds by electrolysis of CO2 and / or H2O is one option to achieve this. We chose solid oxide reactors for this application, inter alia, because in principle they can be operated cyclically in electrolyser (SOE) and fuel cell (SOFC) modes.
Results will be presented of measurements of ohmic and electrode polarization resistances and global performances for CO2 splitting to CO and O2 in micro-tubular solid oxide electrolysers (SOEs), with different types of current collectors; electrolysis of steam and (CO2 + steam) exhibited similar behaviour.
Silver or nickel wire current collectors, with and without silver or nickel paste, were used to contact the 220 μm thick inner lumen Ni-YSZ electrode (SOE cathode) of micro-tubular solid oxide electrolysers [1] (SOEs: Ni-YSZ|YSZ|YSZ-LSM|LSM) incorporating 34 μm thick yttria-stabilized zirconia (YSZ) electrolyte, and 40 μm thick lanthanum strontium manganite (LSM, SOE anode), as described previously for CO2 reduction [2]. Silver wire and paste was used as the current collector for the LSM electrode.
As shown in Fig. 1, the best performance (ca. 1 A cm-2 at 1.5 V (thermo-neutral potential difference) at 800 °C) was achieved for reactors with nickel wire current collectors alone, implying metallic pastes had no net beneficial effects on area-specific ohmic resistances. Furthermore, applying silver paste had a detrimental effect on the Ni cathode polarization resistance, for reasons that will be presented. Fig. 2 shows polarization and ohmic resistance data at open circuit; similar behaviour was exhibited with potential differences applied to reactors. Ohmic resistances were expected to decrease by using silver wire, due to its higher electronic conductivity compared to nickel, but no stable cell performance was achieved.
References
[1] L. Kleiminger, Ph.D. Thesis, Imperial College London, to be published (2015).
[2] L. Kleiminger, T. Li, K. Li and G. H. Kelsall, RSC Adv., 4 (2014) 50003-50016.

Figure 1
Laser Modification of Micro Porous Layers Used in Polymer Electrolyte Membrane Fuel Cells
Authors: Schulze Mathias , Biswas Indro , Gazdzicki Pawel 
Published: February 2020

In polymer membrane fuel cells (PEMFC) the performance as well as the degradation strongly depends on the water balance inside the fuel cell. The membrane must be humidified for a sufficient ion conductivity, but on the other side the excess product water needs to be removed from the fuel cell in order to avoid flooding of the pore system.
The gas diffusion layer (GDL), which also provides contact to the electrochemically active components, has to achieve the passive management of the water balance. The adjustment of the hydrophobicity of the GDL is crucial for stable operation, and non-uniform hydrophobicity has already been shown to be advantageous.
Typically, gas diffusion electrodes for polymer electrolyte fuel cells (PEFC) consist of conductive medium, either a carbon based powder in the microporous layer (MPL) or carbon felt/fibres/cloth in the macroporous backing, and a hydrophobicity impregnation agent like polytetrafluoroethylene (PTFE). The ratio of these components determines the hydrophobicity, which effects the performance. The MPL was modified by laser irradiation. The effect of the laser radiation on the MPL were characterized by x-ray photoemission spectroscopy, Raman and infrared absorption spectroscopy and correlated to the change in the hydrophobic properties.
In particular, non-uniform hydrophobicity was applied and also tested in PEMFC. The introduction of channels of reduced hydrophobicity leads to several benefits. The observed current density distributions became more homogeneous than that of MPL without additional modification. Thus, the area with extreme current densities decreases, resulting in a more homogeneous ageing and, consequently, in an improved lifetime. Moreover, this modification leads to distinct performance increase in certain combinations of CCM and GDL. As an additional finding, not every combination can be improved, or is even performing well.
Acknowledgements
The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) for Fuel Cell and Hydrogen Joint Technology Initiative under Grant No. 303446 (IMPALA).
Investigate of Cr Caused Degradation for SmxSr1-XMnO3 Cathode in the SOFC Atmosphere
Authors: Pu Jian , Xiong Chunyan 
Published: February 2020

Solid Oxide Fuel Cell(SOFC) is a high efficiency, environmental friendly energy exchange equipment . Interconnect is one of the necessary components in SOFC. However, the Cr evaporate from interconnect may react with cathode material and lead to severe degradation of SOFCs. This study demonstrate the significant effect of Cr- poisoning on the performance of SmxSr1-xMnO3(SSM) cathode. After 200h long-term aged with Cr at open circuit potential and short term test under cathodic current , the SSM always shows very slow Cr caused degradation rate and low polarization resistance at 750℃. This results indicate that the SSM is a promising candidate cathode material for SOFCs. The remarkable high anti-Cr poisoning effects may ascribe to the Sm in A site of ABO3 perovskite has smaller size which lead to more robust bonding.
Study on Electrochemical Analysis of Supercapacitor Electrodes Containing Modified Reduced Graphene Oxide and Titanium Dioxide
Authors: Kim Seok , Jo Eun-saem , Kim Hoeseung , Jung Yongju 
Published: February 2020

Graphene has attracted tremendous attention in spacious energy storage fields due to its high conductivity, excellent electrical and mechanical stability, and large specific surface area [1]. However, graphene shows lower electrochemical performance than theoretical reports because of restacking or agglomeration induced by strong van der Waals interactions between adjacent layers. To prevent this phenomenon and improve electric properties, transition metal oxides or hydroxides are generally introduced into the interlayer of graphene [2]. Among diverse transition metal oxides, TiO2 which has numerous advantages such as a high specific energy density, strong oxidizing power, low cost and environment friendly considered as a promising electrode material. In reported study, TiO2 / rGO composite was synthesized by two-step method [2]. Herein, we firstly designed a facile one-step method through the sol-gel approach to synthesize TiO2 / rGO composites, and they exhibited excellent electrochemical performances.
Graphite oxide (GO) was synthesized by a modified Hummers method [3] and as reported before [4-5]. GO was dispersed in DI water and sonicated for 30 min. The mixture of titanium (IV) isopropoxide (TIP), ethanol and acetic acid added in the GO solution. Ammonium hydroxide was then added until pH 8~9 in dropwise under stirring for 1 hour at room temperature to form a brownish-black suspension. After this process, the obtained solution was sealed into a Teflon lined stainless steel autoclave at 160ºC for 3 hours. We can finally obtained TiO2 / rGO composite after filtering, washing and drying in air at 60ºC for 12 hours.
We analyzed morphological properties of the synthesized composites using scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). We confirmed TiO2 / rGO hybrid composites were well anchored on the interlayer of the graphene nanosheets. We also examined electrochemical performances of the composites with cyclic voltammetry (CV), electrical impedance spectroscopy (EIS) and galvanostatic charge-discharge curve. We studied a facile one-step sol-gel method for synthesis of titanium dioxide (TiO2) / reduced graphene oxide (rGO) composite. In conclusion, the as-prepared composite can be considered as promising electrode materials owing to high capacitance and long cycle life.

Acknowledgments

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning, Korea (Grant No.: NRF-2011-0009007).

References

[1] W. L. Zhang, H. J. Choi, Chem. Commun., 47 (2011) 12286.
[2] A. Ramadoss, S. J. Kim, Carbon, 63 (2013) 434.
[3] W. S. Hummers Jr., R. E. Offeman, J. Am. Chem. Soc., 80 (1958) 1339.
[4] J. Kim, S. J. Park, S. Kim, Carbon Lett., 14 (2013) 51.
[5] Y. Kim, S. Kim, Electrochimica Acta, 163 (2015) 252.
Ta-Mo Isomorphous Alloy Systems for Metal Gate Apllications
Authors: Yu Hung-Yi , Deng Yong-Jhong , Lai Yi-Sheng 
Published: February 2020

Tantalum-molybdenum (Ta-Mo) thin films with various compositions are deposited on Si and HfO2/Si substrates by rf (radio frequency) magnetron sputtering. The isomorphous Ta-Mo thin film shows an amorphous structure with Mo/Ta rf power at 20/80 W. It is reported that an amorphous structure of gate electrodes can reduce threshold voltage variability among different devices, caused by different orientations of polycrystalline grains [1]. This amorphous layer may eliminate the effect for the fabrication of next generation CMOS devices.
Different thicknesses of HfO2 dielectrics (20, 40, 60, 80, and 100 Å) are obtained by metal-organic chemical vapor deposition. The Ta-Mo thin films are deposited on HfO2/Si by cosputtering Ta and Mo targets. The composition of Ta-Mo alloys are controlled by varying the rf power (0/100, 20/80, 40/60, 60/40, 80/20, 100/0 W) on Ta and Mo targets. After that, a TaN layer is deposited on Ta-Mo layers to form a TaN/Ta-Mo/HfO2/Si MOS capacitor. The capacitor is further annealed at 400oC in a N2-H2 mixture for 30 min to study the thermal stability of the gate structure. The crystal structure is identified by grazing incident angle X-ray diffraction. Chemical bonding of Ta-Mo films is characterized by X-ray photoelectron spectroscopy. The resistivity is measured by using a four-point probe. Electrical properties of the MOS capacitors are characterized by capacitance–voltage (C-V) measurements. The work function is extracted from the C-V curves with different thicknesses of HfO2.
The GIAXRD result suggests that the Ta and Mo phases appear for Ta-Mo films deposited with Mo/Ta rf power at 0/100 W and 100/0 W, respectively. Both of them are body-centered cubic (BCC) structures. For Ta-Mo thin films deposited with different Mo/Ta rf powers, the structures are also BCC structures, except for film deposited with Mo/Ta rf powers at 20/80 W. It exhibits an amorphous structure. In addition, the lattice constant decreases but the grain size increases as the rf power on Mo targets increases. The physical properties of Ta-Mo films and the effective work functions of the bilayer TaN/Ta-Mo gate electrodes will be addressed.
[1] M. E. Grubbs, X. Zhang, M. Deal, Y. Nishi, and B. M. Clemens, Appl. Phys. Lett. 97, 223505 (2010).

Figure 1
Dry and Wet Processed Interface Layer in Ge/High-K Devices Studied by Deep Level Transient Spectroscopy
Authors: Ding YI Ming , Misra Durga 
Published: February 2020

In this work, dry and wet processed interface layer quality in Ge/High-K MOS structure (1) were studied by deep level transient spectroscopy (DLTS) (2). The MOS devices were pulsed from mid-bandgap to accumulation region, then return to mid-bandgap to obtain the majority carrier trap emission information. Figure 1(a-c) shows the DLTS data for three corresponding interface treatment. The Arrhenius plots are shown in Figure 1(d). Comparing the DLTS spectrum, it can be concluded that dry processes have discrete border traps at the interface (H3 and H5). No such traps at the interface of wet processed MOS devices were observed. For all three samples, however, interface like traps were detected (H1, H2, H4). The defects density was estimated by Eq. (1), where is obtained from CV plot using measured . The results suggest that it is around 1013 cm-2/eV for all three samples. This further confirms that the origin of interface state density, Ditobserved for these samples (1) are mainly due to these traps. The time constants in the order of milliseconds were also previously observed. Table I summarizes the Energy levels and cross-sections of these traps. (1)

Acknowledgement:The authors would like to thank K. Tapily, R. D. Clark, S. Consiglio, C. S. Wajda, and G. J. Leusink of TEL Technology Center, Albany, NY, for supplying devices and helpful discussions.
Table I. Arrhenius plot fitting results

H1
H2
H3
H4
H5

ET-EV (eV)
0.16
0.1
0.18
0.04
0.45

(cm2)a

6.3×10-17

1.3×10-19

3.6×10-19

5.8×10-21

8.6×10-13

a Cross section is calculated by assuming = 1020 cm-2 s-1K-2.

Figure 1. Deep level transient spectrum of (a) simple chemical oxidation (Chemox), (b) chemical oxide removal (COR) followed by 1 nm oxide by slot-plane-antenna (SPA) plasma (COR&SPAOx), (c) COR followed by vapor O3 treatment (COR&O3). (d) shows the Arrhenius plots for all three samples.

References

1. Y. Ding, D. Misra, M. N. Bhuyiana, K. Tapily, R. D. Clarkb, S. Consigliob, C. S. Wajda and G. J. Leusink, ECS Transactions, 69, 313 (2015).

2. D. V. Lang, Journal Of Applied Physics, J. Appl. Phys., 45, 3203 (1974).

Figure 1
Ru Film Characterization Correlated to Advanced CMP Slurry Performance
Authors: Stender Matthias , Derecskei Bela , Schlueter James A 
Published: February 2020

Ruthenium has been considered as a barrier liner film for copper in advanced back-end-of-the-line (BEOL) metallization schemes in particular for the 10 nm and beyond technology nodes [1]. Ru shows a lower resistivity than traditionally used barrier films such as Ta or TaN [2] as well as negligible solubility with Cu [3] and Ru films can be deposited with a variety of techniques like CVD or PVD [4], which makes it an attractive candidate. However, new advanced BEOL barrier CMP slurries will have to be developed for this application and Ru is considered a very hard material and chemically inert. Hence it is a big challenge to develop advanced node Ru CMP slurries.
Since Ru films can be deposited with various deposition techniques and onto different substrates the removal rate response of these different films to a given slurry can also be dramatically different. For example we found that the removal with a standard Cu-barrier slurry without any additional additives on Ru film type A was only 20 Å/min whereas it was 200 Å/min on the type B film even though both films had been deposited by PVD. Further investigation of the two films showed that the morphology and in particular the grain size was quite different as shown in the SEM images below.
Interestingly, these two images correlate very well with images in [5] of two films which have been deposited at different plasma pressures and the difference in removal rate can be explained by different residual stresses in the two films as a result of the different plasma pressures.
In this paper we will present the characterization of several different Ru films by XRF (film density), XRD (crystal structure), SEM (grain size and structure), AFM (surface roughness), XPS (atomic composition), contact angle (surface energy) and film hardness by micro/nano indentation. The analytical results will be correlated to CMP polishing performance and in particular on how the different films respond to rate boosting additives in the slurry. The goal is to be formulate a customized slurry by understanding the properties of individual Ru films.
References:
1) C.-C. Yang, S. Cohen, T. Shaw, P.-C. Wang, T. Nogami, and D. Edelstein, IEEE Electron Device Lett., 31, 722 (2010).
2) G.K. Schweitzer, L.L. Pesterfield, The Aqueous Chemistry of the Elements, Oxford, 2010.
3) O. Chyan, T.N. Arunagiri, T. Ponnuswamy, J. Electrochem. Soc., 150 C347 (2003).
4) H. Li, D.B. Farmer, R.G. Gordon, Y. Lin, J. Vlassak, J. Electrochem. Soc. 154 D642 (2007).
5) A. S. Alagoz, J.-D. Kamminga, S. Y. Grachev, T.-M. Lu, T. Karabacak, MRS Proceedings 2009

Figure 1
Bubble Tolerant Liquid Management
Authors: Young Alan 
Published: February 2020

Initially CMP slurries were hand mixed in small quantities and drawn from buckets at the back of the tool using peristaltic pumps. Batch to batch variations adversely affected yields as did pulsatile dispense.
Eventually, automated, batch verified, basement blending and loop distribution systems came into use. These systems reduced batch to batch variation but, still relied upon peristaltic pumps for dispense volume control.
Particle generation from tubing and high chemical cost drove a need for a change at sub-micron (90 Nanometer) geometries. Various flow control schemes were evaluated including paddle wheel, turbine and differential pressure based systems ultimately settling on ultrasonic based flow controllers as the preferred technology.
However, as feature sizes continue to shrink, the chemistries required to achieve smaller feature sizes becomes more and more exotic. Mixtures including peroxides and hydroxides naturally out-gas which produce bubbles in the dispensed flow streams, and in some cases results in a two-phase flow regime. At comparatively low volumetric void fractions bubble concentrations (less than 10%) can adversely affect measurement accuracy of DP, Paddle Wheel, Turbine or Ultrasonic flow measurement technologies to the extent that many of these flow measurement technologies cease to operate satisfactorily.
Malema has developed a mass based, flow controller for slurry and clear chemical dispense applications. Based on Coriolis mass flow rate measurement, the Malema Coriolis Mass Flow Controller (CMFC) is essentially bubble tolerant.
Flow meter / flow controller manufacturers used an assortment of software techniques to filter the effects of these entrained bubbles with limited results. Since Coriolis measures mass directly, bubbles have very little effect on measured or dispensed volumes.
A brief history of the Coriolis Effect, how it is applied to direct mass flow rate measurements will be presented and discussed including a description of Malema’s family of CMFCs and associated performance data.