Enhanced Ionic Conductivity in Ce0.8Gd0.2O2-δ Nanofiber: Effect of the Crystallite Size

2018 ◽  
Vol 281 ◽  
pp. 761-766 ◽  
Author(s):  
Meng Fei Zhang ◽  
Tian Jun Li ◽  
Xiao Hui Zhao ◽  
Hua Jian Zhou ◽  
Wei Pan
Keyword(s):  
Crystallite Size ◽  
Solid Electrolytes ◽  
Average Crystallite Size ◽  
Ionic Transport ◽  
Oxygen Sensors ◽  
Oxide Ion Conductivity ◽  
Crystallite Sizes ◽  
Electrochemical Devices ◽  
The Relationship ◽  
Oxide Ion

The relationship between the microstructure and the conductivity of nanocrystallized oxygen ionic electrolytes has been received great interest since it provides guidelines for designing electrolytes with high performances which might find applications in fuel cells and oxygen sensors. Here, we present a strategy for controlling the calcination temperature to tune the crystallite size and ionic transport properties of solid electrolyte. Different crystallite sizes of Ce0.8Gd0.2O2-δ (CGO) nanofiber electrolytes were prepared. As the average crystallite size decreased from 27 nm to 8 nm, the conductivity of the nanofibers increased by more than five times. An exceptionally high oxide ion conductivity of 0.023 S∙cm-1 for the nanofibers was observed at 550°C. These insights into the effect of the crystallite size on the structure and the conductivity allow a better control of the electrical properties of solid electrolytes, which might foster their applications in electrochemical devices operable at lower temperatures.

scholarly journals The relationship between oxide-ion conductivity and cation vacancy order in the hybrid hexagonal perovskite Ba3VWO8.5

2020 ◽  
Vol 8 (32) ◽  
pp. 16506-16514 ◽  
Author(s):  
Asma Gilane ◽  
Sacha Fop ◽  
Falak Sher ◽  
Ronald I. Smith ◽  
Abbie C. Mclaughlin
Keyword(s):  
Ionic Conductivity ◽  
Long Range ◽  
Cation Vacancy ◽  
Ion Conductivity ◽  
Cation Ordering ◽  
Oxygen Diffusivity ◽  
Oxide Ion Conductivity ◽  
The Relationship ◽  
Oxide Ion

Cation ordering in Ba3VWO8.5 disrupts long-range oxygen diffusivity parallel to the c-axis resulting in reduced ionic conductivity.

Nanoscale Topography of GC/Pt-C and GC/Pt-Ru-C Electrodes Studied by Means of STM, AFM and XRD Methods

2006 ◽  
Vol 518 ◽  
pp. 271-276 ◽  
Author(s):  
A. Kowal ◽  
P. Olszewski ◽  
D.V. Tripković ◽  
R. Stevanović
Keyword(s):  
Crystallite Size ◽  
Surface Area ◽  
Rietveld Method ◽  
High Surface ◽  
High Surface Area ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
Crystallite Sizes ◽  
Nanoscale Topography ◽  
Two Phases

Electrodes, assigned as GC/Pt-C and GC/Pt-Ru-C, were formed by deposition of Ptbased catalysts (47.5 wt % Pt + high surface area carbon) and (54 wt. % Pt-Ru alloy + high surface area carbon) on glassy carbon (GC) discs. X-ray diffraction measurements were used for the determination of the average crystallite size and phase composition of both catalysts. Crystallite size for Pt-C catalyst was 2.9 nm for Pt-fcc. In the diffraction pattern of the Pt-Ru-C catalyst two phases, e.g. Pt-Ru-fcc and Ru-hcp were refined using the Rietveld method. Crystallite sizes were 3.9 nm for Pt-Ru-fcc and 2.8 nm for Ru-hcp. STM observations of the surface of GC/Pt-C and GC/Pt-Ru-C electrodes revealed the presence of metal particles of the size in the range 2-6 nm and Pt-C or Pt- Ru-C agglomerates in the range of several tenth of nm. The thickness of the Nafion covering layer determined by AFM is ca. 100 nm. A simplified scheme of the investigated electrodes was created.

MAGNETIC PROPERTIES OF NANOCRYSTALLINE NiFe2O4 POWDERS PREPARED BY AN AQUEOUS OXIDATIVE PRECIPITATION PROCESS

2001 ◽  
Vol 15 (03) ◽  
pp. 305-312 ◽  
Author(s):  
M. RAJENDRAN ◽  
A. K. BHATTACHARYA ◽  
D. DAS ◽  
S. N. CHINTALAPUDI ◽  
C. K. MAJUMDAR
Keyword(s):  
Magnetic Properties ◽  
Hyperfine Field ◽  
Crystallite Size ◽  
Room Temperature ◽  
Magnetic Hyperfine Field ◽  
Average Crystallite Size ◽  
Precipitation Process ◽  
Saturation Magnetisation ◽  
Crystallite Sizes ◽  
Oxidative Precipitation

Nanocrystalline NiFe 2 O 4 powder has been prepared by an oxidative precipitation process at room-temperature and the crystallite size dependent magnetic properties have been studied. The NiFe 2 O 4 powders prepared at room-temperature had an average crystallite size of 6 nm and showed a reduced saturation magnetisation (M s ) of 3 emu · g -1. The crystallite size was increased by heating the samples to increasingly higher temperatures. The M s value increased from 3 to 40 emu·g -1 as the crystallite size was increased from 6 to 120 nm. The samples having crystallite sizes from 6 to 20 nm were superparamagnetic at room-temperature. The Mössbauer spectrum of the 6 nm sized sample showed a broad quadruple doublet, whereas, the 40 nm sized sample showed a clear sextet pattern, with a hyperfine field values of 466 and 504 kOe for A(tetraheral) and B(octahedral) sublattices, respectively. It is shown that the saturation magnetisation and magnetic hyperfine field values are significantly reduced in nanocrystalline NiFe 2 O 4 as a function of crystallite size.

XRPD/TEM studies of model high-temperature shift catalysts

2006 ◽  
Vol 39 (4) ◽  
pp. 519-526 ◽  
Author(s):  
Rune E. Johnsen ◽  
Alfons M. Molenbroek ◽  
Kenny Ståhl
Keyword(s):  
High Temperature ◽  
Iron Oxide ◽  
Crystallite Size ◽  
Rietveld Method ◽  
Temperature Shift ◽  
Average Crystallite Size ◽  
Model Catalysts ◽  
Crystallite Sizes ◽  
Scherrer Equation

The combination of transmission electron microscopy (TEM) andin situX-ray powder diffraction (XRPD) for the investigation of four model high-temperature shift catalysts makes it possible to obtain and compare information concerning the crystallite and particle shapes and sizes before, during and after the reduction of the synthesized hematite-based model catalyst to the active magnetite-based catalyst. Two chromium-containing iron oxide model catalysts and two pure iron oxide model catalysts were synthesized from hydrated chloride or nitrate salts, resulting in particles with different shapes and sizes. The average crystallite sizes of four model catalysts were determined by XRPD using the Scherrer equation before and after the reduction. The crystallite sizes determined before the reduction were compared with particles sizes determined from TEM images of the same samples. These sizes were generally in good agreement. By using the Rietveld method combined with the Scherrer equation and the Lorentzian Scherrer broadening parameters, the development of the average crystallite size during thein situreduction was demonstrated. This showed that the average crystallite size of the remaining hematite increases when the reduction begins. Additionally, the average crystallite sizes of the reduced samples showed that the chromium-containing model catalysts have the smallest increase in the overall crystallite size.

A Mechanism for the Fast Ionic Transport in Nanostructured Oxide-Ion Solid Electrolytes

2006 ◽  
Vol 18 (22) ◽  
pp. 3005-3009 ◽  
Author(s):  
M. G. Bellino ◽  
D. G. Lamas ◽  
N. E. Walsöe de Reca
Keyword(s):  
Solid Electrolytes ◽  
Ionic Transport ◽  
Nanostructured Oxide ◽  
Oxide Ion

scholarly journals Effect of Silica Embedding on the Structure, Morphology and Magnetic Behavior of (Zn0.6Mn0.4Fe2O4)δ/(SiO2)(100−δ) Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2232
Author(s):  
Thomas Dippong ◽  
Iosif Grigore Deac ◽  
Oana Cadar ◽  
Erika Andrea Levei
Keyword(s):  
Crystallite Size ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Average Crystallite Size ◽  
Chemical Transformations ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Crystallite Sizes ◽  
Ft Ir

The effect of SiO2 embedding on the obtaining of single-phase ferrites, as well as on the structure, morphology and magnetic properties of (Zn0.6Mn0.4Fe2O4)δ(SiO2)100−δ (δ = 0–100%) nanoparticles (NPs) synthesized by sol-gel method was assessed. The phase composition and crystallite size were investigated by X-ray diffraction (XRD), the chemical transformations were monitored by Fourier transform infrared (FT-IR) spectroscopy, while the morphology of the NPs by transmission electron microscopy (TEM). The average crystallite size was 5.3–27.0 nm at 400 °C, 13.7–31.1 nm at 700 °C and 33.4–49.1 nm at 1100 °C. The evolution of the saturation magnetization, coercivity and magnetic anisotropy as a function of the crystallite sizes were studied by vibrating sample magnetometry (VSM) technique. As expected, the SiO2 matrix shows diamagnetic behavior accompanied by the accidentally contribution of a small percent of ferromagnetic impurities. The Zn0.6Mn0.4Fe2O4 embedded in SiO2 exhibits superparamagnetic-like behavior, whereas the unembedded Zn0.6Mn0.4Fe2O4 behaves like a high-quality ferrimagnet. The preparation route has a significant effect on the particle sizes, which strongly influences the magnetic behavior of the NPs.

Influence of Preparation Temperature on Performance of Ce1-xPrxO2 Ultrafine Powder Prepared by a Microemulsion Process

2008 ◽  
Vol 368-372 ◽  
pp. 784-786 ◽  
Author(s):  
Jun Yang ◽  
Zhen Feng Zhu ◽  
Jing Ping Li
Keyword(s):  
Crystallite Size ◽  
Calcination Temperature ◽  
Average Crystallite Size ◽  
Ultrafine Powder ◽  
Microemulsion System ◽  
Sem Images ◽  
Preparation Temperature ◽  
Annealing Conditions

A W/O microemulsion system composed of OP-emolsifier / water / cyclohexane / 1-Pentanol was adopted to prepare ultrafine Ce1-xPrxO2 powder via the reaction between the precipitants of cerium and praseodymium salt solved in the nano reactors. The influence of the annealing conditions on the preparation of Ce1-xPrxO2 powder was investigated. It was shown that, with the increase of calcination temperature from 400 °C to 800 °C, the average crystallite size of the particles increases from 9.5 nm to 25.8 nm. FE-SEM images showed that shape of the particles is layered and sheet-like.

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