Radiation Effects in Murataite Ceramics

2003 ◽  
Vol 807 ◽  
Author(s):  
J. Lian ◽  
L. M. Wang ◽  
R. C. Ewing ◽  
S. V. Yudintsev ◽  
S. V. Stefanovsky
Keyword(s):  
Rare Earth ◽  
Critical Temperature ◽  
Rare Earth Elements ◽  
Temperature Dependence ◽  
Radiation Effects ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Structural Disorder ◽  
Fluorite Structure ◽  
Potential Host

ABSTRACTSynthetic murataite, an isometric, derivative of the fluorite-structure, has been proposed as a potential host phase for the immobilization of rare earth elements (REE) and actinides. A 1 MeV Kr+ ion irradiation has been performed on synthetic murataite ceramics in the system Ca-Ti-U-Mn-Al-Zr-Ce-O for different structural multiples of the fluorite unit cell. The temperature dependence of the amorphization dose has been determined. A higher critical temperature was obtained for the disordered murataite as compared to that of murataite superstructures, suggesting that murataite becomes more “resistant” to ion beam-induced damage with increasing degrees of structural disorder.

HREM and Image Simulation of Short-Range-Order Domains in Ion Irradiated Zirconolite

2000 ◽  
Vol 6 (S2) ◽  
pp. 392-393
Author(s):  
S. X. Wang ◽  
L. M. Wang ◽  
R. C. Ewing
Keyword(s):  
High Temperature ◽  
Critical Temperature ◽  
Temperature Dependence ◽  
Short Range ◽  
Radiation Effects ◽  
Short Range Order ◽  
Fluorite Structure ◽  
Range Order ◽  
Image Simulation ◽  
Ion Species

Zirconolite (CaZrTi2O7) is an important phase proposed for immobilization of plutonium. Radiation effects in zirconolite were studied by 1 MeV Kr+ and 1.5 MeV Xe+ irradiation at various temperatures. Zirconolite became amorphous at temperatures below a critical temperature, Tc. The critical temperature was found to be a function of ion species: Tc - 654 K for 1 MeV Kr+ and 710 K for 1.5 MeV Xe+. The temperature dependence of amorphization dose is shown in FIG. 1. Above Tc, the specimen remained crystalline after prolonged irradiation (up to 3.6×l015 ions/cm2). However, the high-temperature irradiated zirconolite was transformed into the fluorite structure (as shown by the strong diffraction maxima in FIG. 2). In addition to the maxima from the fluorite structure, strong diffuse maxima were observed surrounding the Bragg position of pyrochlore superlattice (FIG. 2).

scholarly journals The Occurrence States of Rare Earth Elements Bearing Phosphorite Ores and Rare Earth Enrichment Through the Selective Reverse Flotation

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 698
Author(s):  
Wenxiang Chen ◽  
Feng Zhou ◽  
Hongquan Wang ◽  
Sen Zhou ◽  
Chunjie Yan
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Ion Beam ◽  
Western China ◽  
Reverse Flotation ◽  
Flotation Process ◽  
Element Bearing ◽  
Element Contents

The reserve of rare-earth element-bearing phosphorite ores in Guizhou province in western China is huge. Increased demand for the different products manufactured from rare-earth elements has resulted in an extreme need for reasonable and comprehensive extraction of rare-earth elements. An improved understanding of rare-earth element occurrence states in single minerals of ores is important for their further processing. In this paper, rare-earth element contents were analyzed by inductively coupled plasma (ICP), and the occurrence states in single minerals were further investigated through SEM-EDS and focused ion beam-scanning electron microscope (FIB-SEM) methods. The results indicate that rare-earth element contents of apatite are far more than that of dolomite. No independent mineral of rare-earth elements exists for the studied sample. Rare-earth elements are present in the form of ions in the lattices of apatite. Based on the analysis of occurrence states and properties in single minerals, the distribution of rare-earth elements in the flotation process was investigated by reverse flotation technology. It shows that rare-earth elements are mainly concentrated in apatite concentrate. Under the optimized conditions, the P2O5 grade increases from 11.36% in the raw ore to 26.04% in the concentrate, and the recovery is 81.92%, while the total rare-earth oxide grade increases from 0.09% to 0.21% with the recovery of 80.01%, which is similar to P2O5 recovery. This study presents the feasibility of extracting rare-earth elements from rare-earth element-bearing phosphorite ores through the flotation of apatite.

Radiation Effects in Nonmetals: Amorphization, Phase Decomposition, and Nanoparticles

1998 ◽  
Vol 540 ◽  
Author(s):  
A. Meldrum ◽  
L.A. Boatner ◽  
C.W. White ◽  
D.O. Henderson
Keyword(s):  
Ion Implantation ◽  
Electron Irradiation ◽  
Radiation Effects ◽  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Semiconductor Nanocrystals ◽  
Heavy Ion ◽  
Fused Silica ◽  
Near Surface

AbstractRadiation effects in nonmetals have been studied for well over a century by geologists, mineralogists, physicists, and materials scientists. The present work focuses on recent results of investigations of the ion-beam-induced amorphization of the ABO4 compounds – including the orthophosphates (LnPO4; Ln = lanthanides) and the orthosilicates: zircon (ZrSiO4), hafnon (HfSiO4), and thorite (ThSiO4). In the case of the orthosilicates, heavy-ion irradiation at elevated temperatures causes the precipitation of a nanocrystalline metal oxide. Electron irradiation effects in these amorphized insulating ceramics can produce localized recrystallization on a nanometer scale. Similar electron irradiation techniques were used to nucleate monodispersed compound semiconductor nanocrystals formed by ion implantation of the elemental components into fused silica. Methods for the formation of novel structural relationships between embedded nanocrystals and their hosts have been developed and the results presented here demonstrate the general flexibility of ion implantation and irradiation techniques for producing unique near-surface microstructures in ion-implanted host materials.

Comparison of Conductivity Produced in Polymers and Carbon Films by Pyrolysis and High Energy Ion Irradiation

1983 ◽  
Vol 27 ◽  
Author(s):  
T. Venkatesan ◽  
R. C. Dynes ◽  
B. Wilkens ◽  
A. E. White ◽  
J. M. Gibson ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Carbon Film ◽  
Physical Nature ◽  
High Energy ◽  
Carbon Films ◽  
Chemical Degradation ◽  
Beam Irradiation ◽  
Ion Beam Irradiation

ABSTRACTThe electrical properties of pyrolyzed polymers have been studied recently.1,2 It has been shown that organic, polymeric3 and non-polymeric4 films can be made conductive (ρ ~ 10−3Ωcm) by ion beam irradiation. Common to all of the films was the presence of carbon as a constituent element and both pyrolysis and ion beam irradiation3 was shown to increase the relative carbon content of the films. The ion beam irradiated organic films 3,4 exhibited a temperature dependence of their resistivity of the form ρ(T) = ρ∞e−(TЛ)*, where ρ is the ion-induced resistivity, ρ∞ and T0 are constants and T is the temperature. At very high doses of irradiation (1017cm−2Ar+@ 2MeV) the film resistivity was temperature independent. Very similar transport properties were observed in the pyrolyzed polymers1 as well, though the lowest resistivities achieved were higher than the resistivity values observed in the ion irradiated3 polymer films. In both the pyrolysis and ion-irradiation experiments the temperature dependence has been explained by a model due to Sheng and Abeles,5 which involves charge transport by hopping between conducting islands embedded in an insulating matrix. Such striking similarities between two distinctly different modes of energy deposition in the films, prompted us to compare the effects of pyrolysis and ion irradiation in different carbon containing films. We compared both a polymer (HPR-204°) and a film of electron beam evaporated carbon film. While in the former case one would observe chemical degradation as well as structural modification, by studying pure carbon films the physical nature of the processes could be clarified. We report metallic carrier densities in both films and evidence for significant structural rearrangement. We conclude that pyrolysis and ion beam irradiation have similar effects on both polymer and carbon films.

Effects of ion beam irradiation on the crystallization of Copper films

1995 ◽  
Vol 396 ◽  
Author(s):  
Shunichi Hishita ◽  
Keiji Oyoshi ◽  
Shigeru Suehara ◽  
Takashi Aizawa
Keyword(s):  
Radiation Effects ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Oxygen Adsorption ◽  
Copper Films ◽  
Beam Irradiation ◽  
Ion Beam Irradiation ◽  
Random Orientation ◽  
Epitaxial Relationship ◽  
Combined Use

AbstractRadiation effects of 2 MeV Ar+ ions on the crystallization of copper films were investigated with or without oxygen adsorption. Metal copper films of 1-5 nm thickness deposited on SrTiO3 (100) at 300K. by evaporation consisted of fine crystals with random orientation. The crystals were grown without epitaxial relationship to the substrate by ion irradiation. The epitaxial growth of copper crystals was achieved by the combined use of oxygen adsorption and ion irradiation. The epitaxial relationship between the film and the substrate was determined Cu (100) // SrTiO3( 100) and Cu [001] // SrTiO3 [001].

Temperature Dependence of DC Conductivity in Ion-Beam-Irradiated Glassy Carbon

1990 ◽  
Vol 201 ◽  
Author(s):  
Dougal McCulloch ◽  
Steven Prawer
Keyword(s):  
Electrical Conductivity ◽  
Temperature Dependence ◽  
Glassy Carbon ◽  
Ion Irradiation ◽  
Functional Dependence ◽  
Ion Beam ◽  
Variable Range Hopping ◽  
Beam Irradiation ◽  
Ion Beam Irradiation ◽  
Ion Species

AbstractThe electrical conductivity of ion beam irradiated Glassy Carbon has been investigated in the temperature range 100 to 300 K. Ion species used were C+ and N+ with doses between 1014 and 1018 ions/cm2. Ion beam irradiation was found to lower the conductivity of Glassy Carbon by up to six orders of magnitude. The temperature dependence of the conductivity in ion beam modified Glassy Carbon has been measured. The functional dependence was found to remain largely unchanged by ion irradiation despite the large overall decrease in the conductivity. The results are interpreted in terms of a model which includes a variable range hopping and strongly scattering metallic components.

Temperature Dependence of Ion Beam Mixing of Ingaas Marker Layers in GaAs

1993 ◽  
Vol 311 ◽  
Author(s):  
D.D. Forbes ◽  
J.J. Coleman ◽  
J.J. Klatt ◽  
R.R. Averback
Keyword(s):  
Temperature Dependence ◽  
Secondary Ion Mass Spectrometry ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Ion Beam Mixing ◽  
Gaas Matrix ◽  
Similar Temperature Dependence ◽  
Mixing Parameter ◽  
Similar Temperature ◽  
Secondary Ion

ABSTRACTIon beam mixing of In0.20Ga0.80As quantum well marker layers in GaAs following 1 MeV Kr ion irradiation has been measured as a function of irradiation temperature and fluence. Secondary Ion Mass Spectrometry (SIMS) was used to measure the diffusion of the In0.20Ga0.80As layer following irradiation at various temperatures. Rutherford Backscattering (RBS) and channeling methods were used to determine the extent of the amorphization as a result of the implantation. The mixing parameter of the In0.20Ga0.80As in the GaAs matrix increased from σ120 Å5/eV at 77K to σ160Å5/eV in the temperature range of 300K–450K, but decreased somewhat at 573K. This behavior of In0.20Ga0.80As marker layers will be compared to AlAs marker layers which show similar temperature dependence. These results are interpreted on the basis of thermal spikes and crystal structure.

Temperature Dependence of Magnetic EXAFS for Rare Earth Elements

2005 ◽  
pp. 600
Author(s):  
H. Wende ◽  
A. Scherz ◽  
C. Sorg ◽  
Z. Li ◽  
P. Poulopoulos ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Temperature Dependence

Ion-Induced Amorphization of Murataite

2002 ◽  
Vol 713 ◽  
Author(s):  
Jie Lian ◽  
Sergey V. Yudintsev ◽  
Sergey V. Stefanovsky ◽  
Olga I. Kirjanova ◽  
Rodney C. Ewing
Keyword(s):  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Pyrochlore Structure ◽  
Fluorite Structure ◽  
In Situ Tem ◽  
Cell Parameters ◽  
Unit Cells ◽  
Radiation Resistant

ABSTRACTMurataite A4B2C7O22-x, where A = Na+, Ca2+, REE3+, An3+/4+; B = Mn2+/3+, Zn2+; C = Ti4+, Fe3+, Al3+; 0≤x≤1, is an isometric, derivative of the fluorite-structure. Murataite is potentially suitable as a phase for the immobilization of rare earth (REE) and actinide elements (An). Murataite structures with three-(3C), five-(5C), and eight-fold (8C) multiples of the fluorite unit cell parameters have been identified. Radiation-induced amorphization of murataite has been investigated by 1 MeV Kr+ ion irradiation of three ceramic samples produced by melting in a resistive furnace and a cold crucible at 1400-1600 °C. The 1 MeV Kr+ ion irradiations were performed at room temperature using IVEM-Tandem Facility at Argonne National Laboratory. Radiation damage was observed by in-situ TEM. Initially, the irradiation caused disordering of the murataite structure. Murataite was rendered fully amorphous at a dose of (1.7∼1.9)Á1018 ion/m2. The pyrochlore structure phase (2C) is more radiation resistant to ion irradiation-induced amorphization than the murataite structure. Combining results on murataite with those pyrochlore and fluorite, a generally increasing trend in the susceptibility to ion beam damage is found in the fluorite-related structures as a function of the increasing multiples of the fluorite unit cells.

Sign in / Sign up

Export Citation Format

Share Document