Waste Glass Alteration Processes, Surface Layer Evolution and Rate Limiting Steps

1993 ◽  
Vol 333 ◽  
Author(s):  
D. E. Clark ◽  
R. L. Schulz ◽  
G. G. Wicks ◽  
A. R. Loading
Keyword(s):  
Field Experiments ◽  
Secondary Ion Mass Spectrometry ◽  
Volume Ratio ◽  
Waste Glass ◽  
Aqueous Environment ◽  
Surface Layers ◽  
Factors Affecting ◽  
Alteration Processes ◽  
Rate Limiting ◽  
Secondary Ion

ABSTRACTThis paper provides an overview of waste glass alteration. Emphasis is on the evolution of surface layers and factors affecting the alteration rate when glass is subjected to an aqueous environment. The extent, type and rate of alteration is determined by a variety of parameters including time, temperature, glass composition, pH, Eh, composition of leachate/geology, the presence of other engineered barriers, flow conditions and surface area/volume ratio. Models (based on kinetic and thermodynamic considerations) developed by other researchers that are consistent with the experimental observations from the laboratory and field experiments are discussed. The morphology of the surface layers as described by interpretation of secondary ion mass spectrometry (SIMS) analyses on waste glasses and the role the various layers play in the alteration process is presented as well.

Correlation of Laboratory and Stripa Field Leaching Studies

1988 ◽  
Vol 127 ◽  
Author(s):  
B. K. Zoitos ◽  
D. E. Clark ◽  
A. R. Lodding ◽  
G. G. Wicks
Keyword(s):  
Laboratory Study ◽  
Secondary Ion Mass Spectrometry ◽  
Field Tests ◽  
Surface Layers ◽  
Infrared Reflection ◽  
Significant Difference ◽  
Field Samples ◽  
Surface Alteration ◽  
Infrared Reflection Spectroscopy ◽  
Secondary Ion

ABSTRACTA variety of surface sensitive techniques has been used to assess surface layers formed on SRL 165 waste glass specimens from the Stripa burial study and from a laboratory study designed to simulate conditions of the Stripa environment. The laboratory study included static and slow flow tests carried out for periods up to 6 and 24 months, respectively. Comparisons of leached layers formed in the two studies are based upon secondary ion mass spectrometry (SIMS), Fourier transform infrared reflection spectroscopy (FTIRRS), and scanning electron microscopy-electron microprobe (SEM-EMP) analysis.Results demonstrate that surface layers having similar trends in elemental profiles were developed in both lab and field tests. It was also found that both sets of samples showed similar changes in FTIRR spectra. One significant difference between the lab and field samples was that surface alteration, as indicated by changes in FTIRR spectra and leached layer thickness (from SIMS), occurred more rapidly in the lab tests.

The Effect of Temperature and Si Concentration on the Mixing of AlAs/GaAs Superlattices

1986 ◽  
Vol 77 ◽  
Author(s):  
Ping Mei ◽  
H. W. Yoon ◽  
T. Venkatesan ◽  
S. A. Schwarz ◽  
J. P. Harbison
Keyword(s):  
Activation Energy ◽  
Molecular Beam ◽  
Secondary Ion Mass Spectrometry ◽  
Diffusion Length ◽  
Dopant Concentration ◽  
Effect Of Temperature ◽  
Surface Layers ◽  
Near Surface ◽  
Depth Profiles ◽  
Secondary Ion

ABSTRACTThe intermixing of AlAs/GaAs superlattices has been investigated as a function of Si concentration following anneals in the range of 500 to 900 C. The superlattice samples were grown by molecular beam epitaxy(MBE) and the near surface layers were doped with silicon at concentrations of 2×10 to 5×1018 cm-3. Si and Al depth profiles were measured with secondary ion mass spectrometry (SIMS).The diffusion length and activation energy of Al as a function of silicon dopant concentration are derived from the SIMS data. In the temperature range studied an activation energy for the Al interdiffusion of -4eV is observed with the diffusion coefficients increasing rapidly with Si concentration.

Aspects of high-resolution imaging with a scanning ion microprobe

1986 ◽  
Vol 44 ◽  
pp. 750-751
Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
Y. L. Wang
Keyword(s):  
Metal Ion ◽  
Secondary Ion Mass Spectrometry ◽  
Chromatic Aberration ◽  
Ion Source ◽  
Ion Microprobe ◽  
Emission Pattern ◽  
Intrinsic Resolution ◽  
Resolution Imaging ◽  
20 Nm ◽  
Secondary Ion

We have shown the feasibility of 20 nm lateral resolution in both topographic and elemental imaging using probes of this size from a liquid metal ion source (LMIS) scanning ion microprobe (SIM). This performance, which approaches the intrinsic resolution limits of secondary ion mass spectrometry (SIMS), was attained by limiting the size of the beam defining aperture (5μm) to subtend a semiangle at the source of 0.16 mr. The ensuing probe current, in our chromatic-aberration limited optical system, was 1.6 pA with Ga+ or In+ sources. Although unique applications of such low current probes have been demonstrated,) the stringent alignment requirements which they imposed made their routine use impractical. For instance, the occasional tendency of the LMIS to shift its emission pattern caused severe misalignment problems.

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