scholarly journals Study on Electrical conductivity and Activation Energy of doped Ceria nanostructures

2018 ◽  
Vol 3 (1) ◽  
pp. 49-53 ◽  
Author(s):  
N. S. Chitra Priya ◽  
K. Sandhya ◽  
Deepthi N. Rajendran
Keyword(s):  
Activation Energy ◽  
Nanocrystalline Materials ◽  
Arrhenius Plot ◽  
Fluorite Structure ◽  
Solid State Reaction Method ◽  
Crystalline Solid ◽  
Doped Ceria ◽  
Sem Images ◽  
Nano Crystalline ◽  
Xrd Patterns

Abstract Ce0.8Gd0.2O2−δ (GDC) and Ce0.8Sm0.2O2−δ (SDC) nanocrystalline materials are prepared by a solid state reaction method. The synthesized nano crystalline solid solutions have cubic fluorite structure as evident from XRD patterns. The materials are qualitatively analyzed by FTIR. The morphology, size and shape of grains etc. are identified from the SEM images. The grain size of GDC is smaller than that of SDC. The better morphology is obtained for GDC. Hence, this is electrically characterized. The activation energy is calculated from the slope of Arrhenius plot (showing variation of conductivity with temperature).

scholarly journals Studies on Highly Dense Pure YIG Polycrystalline Ceramics Fabricated by Tape-casting Method

2020 ◽  
Author(s):  
Chong Zhao ◽  
Yingkui Li ◽  
Xiaofei Shen ◽  
Zhijun Cao ◽  
Zhiquan Cao ◽  
...  
Keyword(s):  
Tape Casting ◽  
Solid State Reaction Method ◽  
Grain Structure ◽  
Casting Method ◽  
Forming Process ◽  
Sem Images ◽  
Polycrystalline Ceramics ◽  
Pure Phase ◽  
One Step ◽  
Xrd Patterns

Abstract Pure phase Y3Fe5O12 (YIG) ceramics was successfully produced by tape-casting forming process and one-step solid-state reaction method. With the sintering temperature above 1100 ºC, the pure phase YIG ceramics was synthesized with no YIP or Fe2O3 phase in XRD patterns. YIG ceramic sintering at 1400 ºC for 10 h showed a clear grain structure with an obvious grain boundary, and no pores were observed in the SEM images. YIG ceramics in this paper has a high relative density which was 99.8% and the saturation magnetization was 28.2 emu/g at room temperature. The hysteresis loss at temperatures of 230-360 K was smaller than 10 mJ/kg. The tan Se was nearly zero at 6~7 GHz and 11~12 GHz, showing that it can be used as a good material for microwave applications. In addition, the low values of tan and tan indicates that it may have a good electromagnetic wave absorption ability.

Synthesis and Characterization of Sm1-xZrxFe1-yMgyO3 (x, y = 0.5, 0.7, 0.9) as Possible Electrolytes for SOFCs

2018 ◽  
Vol 765 ◽  
pp. 49-53 ◽  
Author(s):  
Abdalla Mohammed Abdalla ◽  
Shahzad Hossain ◽  
Nikdalila Radenahmad ◽  
Pg Mohammad Iskandar Petra ◽  
Mahendra Rao Somalu ◽  
...  
Keyword(s):  
Impedance Spectroscopy ◽  
Rietveld Refinement ◽  
Electrochemical Impedance ◽  
Bragg Reflection ◽  
Solid State Reaction Method ◽  
Perovskite Oxide ◽  
Molar Ratio ◽  
Sem Images ◽  
Ionic Size ◽  
Xrd Patterns

The novel perovskite oxide series of Sm1-xZrxFe1-yMgyO3 (x,y = 0.5, 0.7, 0.9) were synthesized by solid state reaction method. X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and conductivity analysis were carried out. XRD patterns of sintered materials revealed the shifted Bragg reflection to higher angle for the higher content of Zr and Mg. This is related to the ionic size of the dopant elements. Rietveld refinement showed that all compounds crystallized in cubic space group of Fm-3m. SEM images showed that the grains were well defined with highly dense surfaces makes it potential as an electrolyte material in solid oxide fuel cells (SOFCs) or gases sensors. Impedance spectroscopy at 550-800 °C shows that conductivity is higher at higher temperature. Sm0.5Zr0.5Fe0.5Mg0.5O3 shows the highest conductivity of 5.451 × 10-3 S cm-1 at 800 °C. It was observed that 50% molar ratio of Mg and Zr doping performed highest conductivity.

scholarly journals Synthesis of LiNi0.85Co0.14Al0.01O2 Cathode Material and its Performance in an NCA/Graphite Full-Battery

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1886 ◽  
Author(s):  
Cornelius Satria Yudha ◽  
Soraya Ulfa Muzayanha ◽  
Hendri Widiyandari ◽  
Ferry Iskandar ◽  
Wahyudi Sutopo ◽  
...  
Keyword(s):  
Cathode Material ◽  
Solid State Reaction Method ◽  
Electrochemical Performances ◽  
Sem Images ◽  
Voltage Range ◽  
Reaction Method ◽  
Artificial Graphite ◽  
Synthesis Routes ◽  
Xrd Patterns ◽  
Co Precipitation

Nickel-rich cathode material, NCA (85:14:1), is successfully synthesized using two different, simple and economical batch methods, i.e., hydroxide co-precipitation (NCA-CP) and the hydroxides solid state reaction method (NCA-SS), followed by heat treatments. Based on the FTIR spectra, all precursor samples exhibit two functional groups of hydroxide and carbonate. The XRD patterns of NCA-CP and NCA-SS show a hexagonal layered structure (space group: R_3m), with no impurities detected. Based on the SEM images, the micro-sized particles exhibit a sphere-like shape with aggregates. The electrochemical performances of the samples were tested in a 18650-type full-cell battery using artificial graphite as the counter anode at the voltage range of 2.7–4.25 V. All samples have similar characteristics and electrochemical performances that are comparable to the commercial NCA battery, despite going through different synthesis routes. In conclusion, the overall results are considered good and have the potential to be adapted for commercialization.

scholarly journals Tailoring the Activation Energy and the Ionic Properties of Bismuth co-doped SDC Powder Prepared by Solid State Reaction Method

2021 ◽  
Author(s):  
Sandhya Kottooli ◽  
N.S. Chitra Priya ◽  
J.S. Revathy ◽  
Deepthi N. Rajendran ◽  
T. Praveen
Keyword(s):  
Activation Energy ◽  
Solid State ◽  
Ionic Conductivity ◽  
Solid State Reaction ◽  
Structure Refinement ◽  
Fluorite Structure ◽  
Solid State Reaction Method ◽  
Nyquist Plot ◽  
Reaction Method ◽  
Co Doped

Abstract Research on fuel cell components has received great attention owing to the growing need for sustainable energy sources. Bismuth (Bi 3+ ) co-doped samarium doped cerium oxide [Ce 1-x Sm x-y Bi y O 2-δ (x=0.2 and y=0, 0.05 and 0.1)] nanosystems were prepared by solid state reaction method. Rietveld structure refinement of X-ray diffraction pattern confirms the cubic fluorite structure along the (111) plane with the decrease in lattice distortion. At the same sintering temperature, pellets exhibit good morphology with better mechanical strength. The conductivity measurements carried out using the Nyquist plot, as well as the modulus spectra, indicate the effect of grain and grain boundary conduction at high temperatures. With the increase in the incorporation of Bi dopant, there is a gradual decrease in ionic conductivity and activation energy. The composition of Ce 0.8 Sm 0.1 Bi 0.1 O 2-δ exhibits less ionic conductivity compared to other samples due to the oxygen vacancies attracted by dopant cations. The effect of Bi 3+ dopants on samarium doped ceria lattice structures and the electrical properties of the systems has been discussed.

scholarly journals Influence of Li2CO3 addition on electrical and magnetic properties of Ni0.6Mg0.4Fe2O4

2020 ◽  
Vol 10 (03) ◽  
pp. 2050003
Author(s):  
M. R. Hassan ◽  
M. T. Islam ◽  
M. N. I. Khan
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Low Frequency ◽  
Solid State Reaction Method ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
Frequency Regime ◽  
Xrd Patterns

In this research, influence of adding Li2CO3 (at 0%, 2%, 4%, 6%) on electrical and magnetic properties of [Formula: see text][Formula: see text]Fe2O4 (with 60% Ni and 40% Mg) ferrite has been studied. The samples are prepared by solid state reaction method and sintered at 1300∘C for 6[Formula: see text]h. X-ray diffraction (XRD) patterns show the samples belong to single-phase cubic structure without any impurity phase. The magnetic properties (saturation magnetization and coercivity) of the samples have been investigated by VSM and found that the higher concentration of Li2CO3 reduces the hysteresis loss. DC resistivity increases with Li2CO3 contents whereas it decreases initially and then becomes constant at lower value with temperature which indicates that the studied samples are semiconductor. The dielectric dispersion occurs at a low-frequency regime and the loss peaks are formed in a higher frequency regime, which are due to the presence of resonance between applied frequency and hopping frequency of charge carriers. Notably, the loss peaks are shifted to the lower frequency with Li2CO3 additions.

scholarly journals Transport Properties and High Temperature Raman Features of Heavily Gd-Doped Ceria

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4148 ◽  
Author(s):  
Cristina Artini ◽  
Sabrina Presto ◽  
Sara Massardo ◽  
Marcella Pani ◽  
Maria Maddalena Carnasciali ◽  
...  
Keyword(s):  
Solid Oxide Fuel Cells ◽  
Oxygen Vacancies ◽  
Arrhenius Plot ◽  
Solid Oxide ◽  
Raman Shift ◽  
Threshold Temperature ◽  
Doped Ceria ◽  
Lower Activation ◽  
Slope Change ◽  
Heavily Doped

Transport and structural properties of heavily doped ceria can reveal subtle details of the interplay between conductivity and defects aggregation in this material, widely studied as solid electrolyte in solid oxide fuel cells. The ionic conductivity of heavily Gd-doped ceria samples (Ce1−xGdxO2−x/2 with x ranging between 0.31 and 0.49) was investigated by impedance spectroscopy in the 600–1000 K temperature range. A slope change was found in the Arrhenius plot at ~723 K for samples with x = 0.31 and 0.34, namely close to the compositional boundary of the CeO2-based solid solution. The described discontinuity, giving rise to two different activation energies, points at the existence of a threshold temperature, below which oxygen vacancies are blocked, and above which they become free to move through the lattice. This conclusion is well supported by Raman spectroscopy, due to the discontinuity revealed in the Raman shift trend versus temperature of the signal related to defects aggregates which hinder the vacancies movement. This evidence, observable in samples with x = 0.31 and 0.34 above ~750 K, accounts for a weakening of Gd–O bonds within blocking microdomains, which is compatible with the existence of a lower activation energy above the threshold temperature.

Preparation and Characterization of NTC NiMn2O4-La1-xCaxMnO3 (0≤x≤0.3) Composite Ceramics

2013 ◽  
Vol 716 ◽  
pp. 78-83 ◽  
Author(s):  
Hui Min Zhang ◽  
Fang Guan ◽  
Ai Min Chang ◽  
Li Jun Zhao
Keyword(s):  
Electrical Resistivity ◽  
Perovskite Structure ◽  
Spinel Structure ◽  
Thermal Constant ◽  
Inrush Current ◽  
Composite Ceramics ◽  
Sem Images ◽  
Conventional Solid State Reaction ◽  
Different Temperatures ◽  
Xrd Patterns

Composite ceramics made of spinel structure NiMn2O4 and CaO-doped perovskite structure LaMnO3 were prepared by a conventional solid state reaction and sintered at different temperatures. The XRD patterns have shown that the major phases presented in the sintered samples are NiMn2O4 compounds with the spinel structure, La1-xCaxMnO3 with the perovskite structure and NiO with a monoclinic structure. SEM images show that the density and grain size of the composite ceramics increases with sintered temperature increasing. The electrical resistivity of the composite ceramics at 25°C is found to change significantly depending on the CaO content, while the thermal constant B is still reasonably large in the range of 2400 to 3000 K. For the composition x = 0.1, the composite with a low electrical resistivity (ρ25°C=4.46Ω·cm) and moderate B value (B25/50=2762K) was obtained. These composites could be applied as potential candidates for NTC thermistors in the suppression of the inrush current.

Synthesis, Characterization and Properties of PANI/(La-Nd Doped BaFe12O19) Composites

2017 ◽  
Vol 727 ◽  
pp. 327-334
Author(s):  
Yan Wang ◽  
Jun Wang ◽  
Xiao Fei Zhang ◽  
Ya Qing Liu
Keyword(s):  
Sol Gel ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Structure Morphology ◽  
Xrd Patterns ◽  
Hexagonal Platelet ◽  
Peak Value ◽  
Properties Of Composites

La-Nd co-doped barium hexaferrites, Ba0.7(LamNdn)0.3Fe12O19 (D-BaM), were successfully prepared by sol-gel method. PANI / D-BaM composites were synthesized by in-situ polymerization in solution. The structure, morphology and properties of samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), four-probe conductivity tester and vector network analyzer. The XRD patterns showed that the crystal structure of all the samples exist as M-type phases. The SEM images revealed that the particles presented a hexagonal platelet-like morphology. The magnetic properties could be improved by substitutions of La and Nd ions. The saturation magnetization (Ms) and coercive force (Hc) increased with the change of La / Nd ratio to the maximum at La / Nd = 3:1. The doped particles have also been embedded in conductive PANI to prepare electromagnetic materials, and the conductivity kept on the order of 10-2. The microwave absorbing properties of composites at 30 MHz-6 GHz improved obviously, the peak value of reflection loss could reach-7.5 dB.

ON THE DIELECTRIC BEHAVIOR OF LiCo3/5Fe2/5VO4 CERAMICS

2010 ◽  
Vol 24 (07) ◽  
pp. 665-670
Author(s):  
MOTI RAM
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Frequency Dependence ◽  
Chemical Method ◽  
Arrhenius Plot ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
Low Frequencies ◽  
Different Temperatures ◽  
Tan Δ

The LiCo 3/5 Fe 2/5 VO 4 ceramics has been fabricated by solution-based chemical method. Frequency dependence of the dielectric constant (εr) at different temperatures exhibits a dispersive behavior at low frequencies. Temperature dependence of εr at different frequencies indicates the dielectric anomalies in εr at Tc (transition temperature) = 190°C, 223°C, 263°C and 283°C with (εr) max ~ 5370, 1976, 690 and 429 for 1, 10, 50 and 100 kHz, respectively. Frequency dependence of tangent loss ( tan δ) at different temperatures indicates the presence of dielectric relaxation in the material. The value of activation energy estimated from the Arrhenius plot of log (τd) with 103/T is ~(0.396 ± 0.012) eV.

Preparation of catalyst as Au doped Mn1Co9Ox/ceramic system for total oxidation of CO

2021 ◽  
Vol 10 (4) ◽  
pp. 39-45
Author(s):  
Phuong Pham Thi Mai ◽  
Hoan Nguyen Quoc ◽  
Quan Do Quoc ◽  
Hung Nguyen Thanh
Keyword(s):  
Sol Gel ◽  
Active Phase ◽  
Catalyst System ◽  
Oxidation Of Co ◽  
Sem Images ◽  
Total Oxidation ◽  
Wet Impregnation ◽  
Modern Analysis ◽  
Catalyst Powder ◽  
Xrd Patterns

In this paper, the Au doped Mn1Co9Ox was investigated for total oxidation of CO. The sol-gel method was applied to prepare this catalyst and some modern analysis methods as XRD, EPR, TPx, SEM were utilized to characterize its properties. The XRD patterns showed only Co3O4 phase without any peaks belonging to Mn or Au. However, the presence of Au and Mn was confirmed by EPR and O2-TPD results. With the aim to further apply catalyst in reality, the Au doped Mn1Co9Ox was deposited on ceramic by sol-gel, wet impregnation. The SEM images displayed the successful coating of active phase on substrate. However, the complete catalyst system didn’t have the high activity in total CO oxidation like the catalyst powder because of large agglomerations on coatings.

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