scholarly journals Structure of Ln2MnxM2-xO7(Ln = rare earth or Y, M = Mo, Ta, Nb or W) Studied by Transmission Electron Microscopy

2003 ◽  
Vol 111 (1299) ◽  
pp. 800-805 ◽  
Author(s):  
Hiromi NAKANO
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rare Earth ◽  
Transmission Electron

Study of Au-CeO2 Nano-particles using analytical Transmission Electron Microscopy

2007 ◽  
Vol 1 (1) ◽  
Author(s):  
P. Gu ◽  
G. Yang ◽  
R.F. Klie
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Rare Earth ◽  
Lattice Parameter ◽  
Nano Particles ◽  
Rare Earth Doping ◽  
Analytical Transmission Electron Microscopy ◽  
Transmission Electron ◽  
Shift Reaction

Cerium oxide doped with various rare earth metals is often used as a support for nano-sized gold particles, and demonstrates to be a promising catalyst for the water gas shift reaction at low temperatures. Many factors are hypothesized to affect the activity of this heterogeneous catalyst, including its loading with gold, the rare-earth dopant, the support and Au particle size, and leaching of the sample. In this study, we examined several Au/CeO2-based catalyst samples, including 2.4% Au/(Ce,Gd)O2, 1.8% Au/(Ce,La)O2 leached, 0.5% Au/(Ce,Gd)O2 leached, and 0.75% Au/CeO2 utilizing analytical transmission electron microscopy. The effects of Au and rare-earth doping on the ceria lattice parameter were investigated, and it was determined that there are no significant variations in the particle's structure or lattice-spacing. Furthermore, the particle sizes of each of the four samples were investigated concluding that although the 1.8% Au/(Ce,La)O2 leached sample has a slightly larger particle size, and the 2.4% Au/(Ce,Gd)O2 sample has a slightly smaller particle size, the differentiation is not adequate to be accountable for the radical distinction in catalytic activity.

Nonepitaxial heterogeneous nucleation of α-sialon in the Ca-doped system

2001 ◽  
Vol 16 (2) ◽  
pp. 578-582 ◽  
Author(s):  
Ya-Wen Li ◽  
Pei-Ling Wang ◽  
Wei-Wu Chen ◽  
Jing-Wei Feng ◽  
Yi-Bing Cheng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rare Earth ◽  
Orientation Relationship ◽  
Heterogeneous Nucleation ◽  
Crystallographic Orientation ◽  
Probable Mechanism ◽  
Transmission Electron ◽  
Low X ◽  
Rare Earth Doped

Ca-α-sialon compacts pressureless-sintered to intermediate temperatures, which consisted of both α-sialon and unreacted α–Si3N4 grains, were investigated with transmission electron microscopy for an overall composition Ca1.8Si6.6Al5.4O1.8N14.2. Special attention was paid to identification of the possible crystallographic orientation between a-sialon and the α–Si3N4 particles. In contrast to the frequently occurring heteroepitaxial nucleation of α-sialon in rare-earth-doped samples with low x values, this study showed that most of the newly formed α-sialon grains had no epitaxial orientation relationship with the α–Si3N4 particles, suggesting nonepitaxial heterogeneous nucleation to be a more probable mechanism for the Ca–α-sialon phase with high Ca concentrations.

Morphology and Pore Structure of Rare Earth Oxides

1991 ◽  
Vol 44 (5) ◽  
pp. 645 ◽  
Author(s):  
LA Bruce ◽  
M Hoang ◽  
S Hardin ◽  
TW Turney
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rare Earth ◽  
Pore Structure ◽  
Rare Earth Oxides ◽  
Thin Sheets ◽  
Adsorption Characteristics ◽  
Transmission Electron ◽  
Adsorption Hysteresis

The morphology observed by transmission electron microscopy of rare earth oxides, prepared by two different routes, has been related to adsorption characteristics for nitrogen at 77 K. The most common morphology was that of thin sheets, then small equiaxed particles, and, more rarely, rod-like particles. The presence of small equiaxed particles was found to be a prerequisite for adsorption hysteresis. Evaluation of linear 't' plots indicated freedom from micropores in all samples, but positive deviations in the presence of sheet morphology at high relative pressures left open the possibility of wedge-like pores in these samples.

Transmission Electron Microscopy Study of α-Decay Damage in Aeschynite and Britholite

1996 ◽  
Vol 465 ◽  
Author(s):  
W. L. Gong ◽  
L. M. Wang ◽  
R. C. Ewing ◽  
L. F. Chen ◽  
W. Lutze
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rare Earth ◽  
Alpha Decay ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Structure Type ◽  
Electron Microscopy Study ◽  
Α Decay ◽  
Transmission Electron

ABSTRACTThe aeschynite structure-type (Ce,Nd,La,Th,U,Ca)(Nb,Ti)2O6, and the rare-earth silicate apatite structure-type with the formula (Ce,La,Nd,Ca,Th)10(SiO4,PO4)6(O,F,OH)2 are important rare-earth and actinide host phases for high-level nuclear waste. Natural phases of these structure-types have calculated alpha-decay doses up to ∼1017 α-events/mg which have accumulated over hundreds of millions of years. Transmission electron microscopy has been used to study the microstructure of α-decay damage in aeschynite and britholite. Electron diffraction analysis of natural aeschynite revealed that minerals originally crystalline gradually lost their crystallinity with increasing alpha-decay doses. Helium bubbles were found in the aeschynite which have accumulated up to ∼2×1016 α-events/mg. These bubbles may nucleate within collision cascades during a-decay damage. Electron irradiation has an enhanced rare-gas migration and the formation of larger bubbles. High-resolution electron microscopy (HRTEM) revealed that amorphization during accumulation of a-decay damage was from alpha-recoil nuclei collision cascades, in both the aeschynite and britholite.

In Situ Synthesis of Hybrid-Reinforced Titanium Matrix Composites

2007 ◽  
Vol 127 ◽  
pp. 155-160
Author(s):  
Di Zhang ◽  
Zhi Feng Yang ◽  
Wei Jie Lu ◽  
Dong Xu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rare Earth ◽  
In Situ Synthesis ◽  
Matrix Composites ◽  
Titanium Matrix ◽  
Titanium Matrix Composites ◽  
Transmission Electron ◽  
Scanning Electron

Novel hybrid TiB, TiC and rare earth oxide (Re2O3) reinforced titanium matrix composites were in situ synthesized utilizing the reaction between Ti, B4C (or C), rare earth (Re) and B2O3 through homogeneously melting in a non-consumable vacuum arc remelting furnace. In this work, Nd and Y were chosen as rare earth (Re) added in the in situ reaction. The thermodynamics of in situ synthesis reaction was studied. The results of X-ray diffraction (XRD) proved that no other phases appeared except for TiB, TiC and Re2O3. The microstructures of the composites were examined by scanning electron microscope (SEM) and backscattered scanning electron microscope (SEM). The results showed that there were mainly three kinds of reinforcements: TiB whiskers, TiC particles and Re2O3 particles. The reinforcements were fine and were homogeneously distributed in the matrix. The interfaces of TiB-TiC and Nd2O3-Ti were examined by high-resolution transmission electron microscopy (HREM).Transmission electron microscopy (TEM) and selected area diffraction (SAD) were used to analyze the orientation relationships of TiB-TiC and Nd2O3-Ti. The orientation relationship between TiB and TiC can be described as: [001] TiB //[001] TiC , (010) TiB //(110) TiC . The orientation relationship of Nd2O3 and α-Ti can be described as: [110] Nd2O3 //[ 1213 ] Ti , (111) Nd2O3 //(1101) Ti , ( 001) Nd2O3 //( 2110 ) Ti .

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