scholarly journals Analysis of Performance Losses and Degradation Mechanism in Porous La2−X NiTiO6−δ:YSZ Electrodes

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2819
Author(s):  
Juan Carlos Pérez-Flores ◽  
Miguel Castro-García ◽  
Vidal Crespo-Muñoz ◽  
José Fernando Valera-Jiménez ◽  
Flaviano García-Alvarado ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Degradation Mechanism ◽  
Ambient Air ◽  
Secondary Phases ◽  
Peak Broadening ◽  
Symmetrical Cell ◽  
Xrd Patterns ◽  
Crystalline Domains ◽  
Analysis Of Performance

The electrode performance and degradation of 1:1 La2−xNiTiO6−δ:YSZ composites (x = 0, 0.2) has been investigated to evaluate their potential use as SOFC cathode materials by combining electrochemical impedance spectroscopy in symmetrical cell configuration under ambient air at 1173 K, XRD, electron microscopy and image processing studies. The polarisation resistance values increase notably, i.e., 0.035 and 0.058 Ωcm2 h−1 for x = 0 and 0.2 samples, respectively, after 300 h under these demanding conditions. Comparing the XRD patterns of the initial samples and after long-term exposure to high temperature, the perovskite structure is retained, although La2Zr2O7 and NiO appear as secondary phases accompanied by peak broadening, suggesting amorphization or reduction of the crystalline domains. SEM and TEM studies confirm the ex-solution of NiO with time in both phases and also prove these phases are prone to disorder. From these results, degradation in La2−xNiTiO6−δ:YSZ electrodes is due to the formation of La2Zr2O7 at the electrode–electrolyte interface and the ex-solution of NiO, which in turn results in the progressive structural amorphization of La18NiTiO6−δ phases. Both secondary phases constitute a non-conductive physical barrier that would hinder the ionic diffusion at the La2−xNiTiO6−δ:YSZ interface and oxygen access to surface active area.

Effect of Water Vapor and SOx in Air on the Cathodes of Solid Oxide Fuel Cells

2007 ◽  
Vol 1041 ◽  
Author(s):  
Seon Hye Kim ◽  
Toshihiro Ohshima ◽  
Yusuke Shiratori ◽  
Kohei Itoh ◽  
Kazunari Sasaki
Keyword(s):  
Water Vapor ◽  
Solid Oxide Fuel Cells ◽  
Degradation Mechanism ◽  
Chemical Species ◽  
Cell Voltage ◽  
Ambient Air ◽  
Open Circuit ◽  
Constant Current ◽  
Constant Current Density

AbstractAmbient air is used as an oxygen source in SOFCs to be commercialized. Various chemical species which can lead to poisoning of SOFC cathodes are included as minor constitutions in air, such as water vapor, SOx, NOx and NaCl etc. However, their effects on the cathode performance have not yet well known, even though they are expected to cause a degradation of the electrode performance and to reduce the long-term durability of SOFCs. Therefore, in this study, we focused on the poisoning caused by water vapor and SOx in the oxygen source to clarify their effects on SOFCs performances and to reveal the degradation mechanism of cathodes. SOFCs with typical electrolyte-supported structure were used in this work, which were composed with ScSZ (10 mol% Sc2O3, 1mol% CeO2, 89 mol% ZrO2) plate with the thickness of 200 µm as electrolyte, NiO-ScSZ (mixture of 56 wt% NiO and 44 wt% ScSZ) porous layer as anode, and two cathode layers of LSM ((La0.8Sr0.2)0.98MnO3) and LSM-ScSZ (mixture of 50 wt% LSM and 50 wt% ScSZ). Power generation characteristics of the cells had been analyzed by measuring cell voltage at a constant current density (200 mA/cm2) and by comparing changes in cell impedance, upon supplying the artificially-contaminated air with water vapor or SOx, to the SOFC cathodes at various operational temperatures. High-resolution FESEM (S-5200, Hitachi) was used to analyze microstructural changes caused by the impurities. Mg Kα radiation from a monochromatized X-ray source was used for XPS measurements (ESCA-3400, KRATOS). AC impedance was measured at various temperatures under the open circuit voltage condition by an impedance analyzer (Solatron 1255B/SI 1287, Solatron), in a frequency range from 0.1 to 105 Hz with an amplitude of 10 mV.

scholarly journals Ba0.5Gd0.8La0.7Co2O6−δ Infiltrated BaZr0.8Y0.2O3-δ Composite Oxygen Electrodes for Protonic Ceramic Cells

2022 ◽  
Author(s):  
qingjie wang ◽  
Sandrine Ricote ◽  
Yu Wang ◽  
Peter Vang Hendriksen ◽  
Jian-Qiang Wang ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Electrode Reaction ◽  
Oxygen Electrode ◽  
Operating Conditions ◽  
Partial Pressures ◽  
Oxygen Electrodes ◽  
Symmetrical Cell ◽  
Proton Migration ◽  
Reaction Processes

Abstract In this study, a composite oxygen electrode is prepared by infiltrating a protonic-electronic conducting material, Ba0.5Gd0.8La0.7Co2O6−δ (BGLC) into a proton-conducting BaZr0.8Y0.2O3-δ (BZY20) backbone. The composite oxygen electrode is studied in a symmetrical cell configuration (BGLC-BZY20//BZY20//BGLC-BZY20). The electrode and cell performance are characterized via electrochemical impedance spectroscopy (EIS) with varying the operating conditions, including temperatures, oxygen, and steam partial pressures, with the purpose to identify and characterize the different electrochemical processes taking place in the oxygen electrode. Three electrode reaction processes are observed in the impedance spectra, which are tentatively assigned to i) diffusion of adsorbed oxygen/proton migration/hydroxyl formation, ii) oxygen reduction, and iii) charge transfer, going from the low- to high-frequency range. The BGLC-BZY20 electrode developed in this work shows a low polarization resistance of 0.22, 0.58, and 1.43 Ω cm2 per single electrode in 3 % humidified synthetic air (21% O2/79% N2) at 600, 550, and 500 °C, respectively. During long-term measurement, the cell shows no degradation in the first 350 hours but degrades afterward possibly due to insufficient material stability.

Strain and Grain Size Effects on Epitaxial PZT Thin Films

2005 ◽  
Vol 875 ◽  
Author(s):  
Oscar Blanco ◽  
Jesus Heiras
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Size Effects ◽  
Short Range ◽  
Rf Sputtering ◽  
Orientation Relationships ◽  
Film Properties ◽  
Peak Broadening ◽  
Xrd Patterns ◽  
Crystalline Domains

AbstractEpitaxial ferroelectric thin films of lead zirconium-titanium oxide, Pb(Zr0.53Ti0.47)O3 (PZT), were successfully grown on SrTiO3, LaAlO3, and Sr(Nb)TiO3 single crystal substrates by a modified RF sputtering technique at high oxygen pressures. The structural properties of the films were evaluated by θ/2θ, ω and ø scans. From these data the crystalline orientation relationships may be extracted. For films grown on SrTiO3 and Sr(Nb)TiO3 substrates, the following orientation relationships were determined: PZT [001] parallel to [001] of the substrate, and PZT [100] parallel to [100] of the substrate. Films grown on LaAlO3 substrates showed a bi-domain crystalline structure with orientation relationships as follows: PZT [100] parallel to [001] of the substrate and PZT [001] parallel to [001] of the substrate. This work was focused to the determination the strain and grain size coefficients, and the analysis of their contribution on the peak broadening in the XRD patterns, and in considering their effects over the ferroelectric behavior. From Williamson-Hall plots, it was possible to conclude that the enhancement of the crystalline film properties (epitaxy and single crystalline domains) reduce the short range strains contribution to peak broadening. On other hand, the grain size contribution to peak broadening was increased with the enhancement of the film cristallinity.

41. Diffusion Badges as a Long-Term, Low-Level Method of Ambient Air Analysis

2005 ◽  
Author(s):  
K. Parker ◽  
S. Rose-Pehrsson ◽  
D. Kidwell
Keyword(s):  
Ambient Air ◽  
Air Analysis ◽  
Low Level ◽  
Level Method

scholarly journals Acute and chronic exposure to air pollution in relation with incidence, prevalence, severity and mortality of COVID-19: a rapid systematic review

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Patrick D. M. C. Katoto ◽  
Amanda S. Brand ◽  
Buket Bakan ◽  
Paul Musa Obadia ◽  
Carsi Kuhangana ◽  
...  
Keyword(s):  
Air Pollution ◽  
Chronic Exposure ◽  
Ambient Air ◽  
Short Term ◽  
Incidence And Mortality ◽  
Acute And Chronic Exposure ◽  
Anthropogenic Pollutant ◽  
Incident Cases ◽  
Incidence Prevalence

Abstract Background Air pollution is one of the world’s leading mortality risk factors contributing to seven million deaths annually. COVID-19 pandemic has claimed about one million deaths in less than a year. However, it is unclear whether exposure to acute and chronic air pollution influences the COVID-19 epidemiologic curve. Methods We searched for relevant studies listed in six electronic databases between December 2019 and September 2020. We applied no language or publication status limits. Studies presented as original articles, studies that assessed risk, incidence, prevalence, or lethality of COVID-19 in relation with exposure to either short-term or long-term exposure to ambient air pollution were included. All patients regardless of age, sex and location diagnosed as having COVID-19 of any severity were taken into consideration. We synthesised results using harvest plots based on effect direction. Results Included studies were cross-sectional (n = 10), retrospective cohorts (n = 9), ecological (n = 6 of which two were time-series) and hypothesis (n = 1). Of these studies, 52 and 48% assessed the effect of short-term and long-term pollutant exposure, respectively and one evaluated both. Pollutants mostly studied were PM2.5 (64%), NO2 (50%), PM10 (43%) and O3 (29%) for acute effects and PM2.5 (85%), NO2 (39%) and O3 (23%) then PM10 (15%) for chronic effects. Most assessed COVID-19 outcomes were incidence and mortality rate. Acutely, pollutants independently associated with COVID-19 incidence and mortality were first PM2.5 then PM10, NO2 and O3 (only for incident cases). Chronically, similar relationships were found for PM2.5 and NO2. High overall risk of bias judgments (86 and 39% in short-term and long-term exposure studies, respectively) was predominantly due to a failure to adjust aggregated data for important confounders, and to a lesser extent because of a lack of comparative analysis. Conclusion The body of evidence indicates that both acute and chronic exposure to air pollution can affect COVID-19 epidemiology. The evidence is unclear for acute exposure due to a higher level of bias in existing studies as compared to moderate evidence with chronic exposure. Public health interventions that help minimize anthropogenic pollutant source and socio-economic injustice/disparities may reduce the planetary threat posed by both COVID-19 and air pollution pandemics.

scholarly journals Systemic Inflammation (C-Reactive Protein) in Older Chinese Adults Is Associated with Long-Term Exposure to Ambient Air Pollution

2021 ◽  
Vol 18 (6) ◽  
pp. 3258
Author(s):  
Mona Elbarbary ◽  
Artem Oganesyan ◽  
Trenton Honda ◽  
Geoffrey Morgan ◽  
Yuming Guo ◽  
...  
Keyword(s):  
Air Pollution ◽  
Systemic Inflammation ◽  
Ambient Air ◽  
Ambient Air Pollution ◽  
Chinese Adults ◽  
Reactive Protein ◽  
Hs Crp ◽  
Older Chinese ◽  
Older Chinese Adults

There is an established association between air pollution and cardiovascular disease (CVD), which is likely to be mediated by systemic inflammation. The present study evaluated links between long-term exposure to ambient air pollution and high-sensitivity C reactive protein (hs-CRP) in an older Chinese adult cohort (n = 7915) enrolled in the World Health Organization (WHO) study on global aging and adult health (SAGE) China Wave 1 in 2008–2010. Multilevel linear and logistic regression models were used to assess the associations of particulate matter (PM) and nitrogen dioxide (NO2) on log-transformed hs-CRP levels and odds ratios of CVD risk derived from CRP levels adjusted for confounders. A satellite-based spatial statistical model was applied to estimate the average community exposure to outdoor air pollutants (PM with an aerodynamic diameter of 10 μm or less (PM10), 2.5 μm or less (PM2.5), and 1 μm or less (PM1) and NO2) for each participant of the study. hs-CRP levels were drawn from dried blood spots of each participant. Each 10 μg/m3 increment in PM10, PM2.5, PM1, and NO2 was associated with 12.8% (95% confidence interval; (CI): 9.1, 16.6), 15.7% (95% CI: 10.9, 20.8), 10.2% (95% CI: 7.3, 13.2), and 11.8% (95% CI: 7.9, 15.8) higher serum levels of hs-CRP, respectively. Our findings suggest that air pollution may be an important factor in increasing systemic inflammation in older Chinese adults.

scholarly journals Classifying the Biological Status of Honeybee Workers Using Gas Sensors

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 166
Author(s):  
Jakub T. Wilk ◽  
Beata Bąk ◽  
Piotr Artiemjew ◽  
Jerzy Wilde ◽  
Maciej Siuda
Keyword(s):  
Gas Sensors ◽  
Laboratory Tests ◽  
Test Chamber ◽  
Ambient Air ◽  
True Positive Rate ◽  
True Positive ◽  
Positive Rate ◽  
Parameters Of Accuracy ◽  
Selection Of

Honeybee workers have a specific smell depending on the age of workers and the biological status of the colony. Laboratory tests were carried out at the Department of Apiculture at UWM Olsztyn, using gas sensors installed in two twin prototype multi-sensor detectors. The study aimed to compare the responses of sensors to the odor of old worker bees (3–6 weeks old), young ones (0–1 days old), and those from long-term queenless colonies. From the experimental colonies, 10 samples of 100 workers were taken for each group and placed successively in the research chambers for the duration of the study. Old workers came from outer nest combs, young workers from hatching out brood in an incubator, and laying worker bees from long-term queenless colonies from brood combs (with laying worker bee’s eggs, humped brood, and drones). Each probe was measured for 10 min, and then immediately for another 10 min ambient air was given to regenerate sensors. The results were analyzed using 10 different classifiers. Research has shown that the devices can distinguish between the biological status of bees. The effectiveness of distinguishing between classes, determined by the parameters of accuracy balanced and true positive rate, of 0.763 and 0.742 in the case of the best euclidean.1nn classifier, may be satisfactory in the context of practical beekeeping. Depending on the environment accompanying the tested objects (a type of insert in the test chamber), the introduction of other classifiers as well as baseline correction methods may be considered, while the selection of the appropriate classifier for the task may be of great importance for the effectiveness of the classification.

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