Concentration Profiles of Implanted Boron Ions in Silicon from Measurements with the Ion Microprobe

ZnO varistors are made by mixing semiconducting ZnO powder with powders of other metal oxides e.g. Bi2O3, Sb2O3, CoO, MnO2, NiO, Cr2O3, SiO2 etc., followed by conventional pressing and sintering. The non-linear I-V characteristics of ZnO varistors result from the unique properties that the grain boundaries acquire as a result of dopant distribution. Each dopant plays important and sometimes multiple roles in improving the properties. However, the chemical nature of interfaces in this material is formidable mainly because often trace amounts of dopants are involved. A knowledge of the interface microchemistry is an essential component in the ‘grain boundary engineering’ of materials. The most important ingredient in this varistor is Bi2O3 which envelopes the ZnO grains and imparts high resistance to the grain boundaries. The solubility of Bi in ZnO is very small but has not been experimentally determined as a function of temperature.In this study, the dopant distribution in a commercial ZnO varistor was characterized by a scanning ion microprobe (SIM) developed at The University of Chicago (UC) which offers adequate sensitivity and spatial resolution.

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Aspects of high-resolution imaging with a scanning ion microprobe

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010014511x ◽

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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Imaging of Al-Li-Cu alloys with a Scanning Ion Microprobe

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100135174 ◽

1990 ◽

Vol 48 (2) ◽

pp. 314-315

Author(s):

K.K. Soni ◽

D.B. Williams ◽

J.M. Chabala ◽

R. Levi-Setti ◽

D.E. Newbury

Keyword(s):

Mass Spectrometry ◽

Secondary Ion Mass Spectrometry ◽

Equilibrium Phase ◽

Icosahedral Symmetry ◽

Ion Microprobe ◽

X Ray ◽

Cu Alloys ◽

Two Phases ◽

The University ◽

Secondary Ion

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.

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Fluidized Catalytic Cracking Catalyst Microstructure as Determined by A Scanning Ion Microprobe

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100135113 ◽

1990 ◽

Vol 48 (2) ◽

pp. 302-303

Author(s):

J.K. Lampert ◽

G.S. Koermer ◽

J.M. Macaoy ◽

J.M. Chabala ◽

R. Levi-Setti

Keyword(s):

Catalytic Cracking ◽

Secondary Ion Mass Spectrometry ◽

Fuel Oil ◽

Ion Microprobe ◽

Fluidized Catalytic Cracking ◽

Ion Probe ◽

Silica Alumina ◽

Resolution Imaging ◽

The University ◽

High Spatial Resolution Imaging

We have used high spatial resolution imaging secondary ion mass spectrometry (SIMS) to differentiate mineralogical phases and to investigate chemical segregations in fluidized catalytic cracking (FCC) catalyst particles. The oil industry relies on heterogeneous catalysis using these catalysts to convert heavy hydrocarbon fractions into high quality gasoline and fuel oil components. Catalyst performance is strongly influenced by catalyst microstructure and composition, with different chemical reactions occurring at specific types of sites within the particle. The zeolitic portions of the particle, where the majority of the oil conversion occurs, can be clearly distinguished from the surrounding silica-alumina matrix in analytical SIMS images.The University of Chicago scanning ion microprobe (SIM) employed in this study has been described previously. For these analyses, the instrument was operated with a 40 keV, 10 pA Ga+ primary ion probe focused to a 30 nm FWHM spot. Elemental SIMS maps were obtained from 10×10 μm2 areas in times not exceeding 524s.

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Measured and Modelled Chlorinated Contaminant Distributions in the St. Clair River Water

Water Quality Research Journal ◽

10.2166/wqrj.1986.029 ◽

1986 ◽

Vol 21 (3) ◽

pp. 332-343 ◽

Cited By ~ 4

Author(s):

C.H. Chan ◽

Y.L. Lau ◽

B.G. Oliver

Keyword(s):

River Water ◽

Suspended Sediment ◽

Water Samples ◽

Concentration Distribution ◽

Suspended Solids ◽

Industrial Area ◽

Concentration Profiles ◽

Detroit River ◽

Chemical Partitioning ◽

Transverse Mixing

Abstract The concentration distribution of hexachlorobutadiene (HCBD), pentachloro-benzene (QCB), hexachlorobenzene (HCB) and octachlorostyrene (OCS) in water samples from transects across the upper and lower St. Clair River and the upper Detroit River were determined on four occasions in 1985. The data show a plume of these contaminants from the Sarnia industrial area. The fluxes and concentration profiles of the contaminants at Port Lambton have been modelled success fully using a simple transverse mixing model. A study on the chemical partitioning between the “dissolved” and “suspended sediment” phases shows that an important contaminant fraction is carried in the river by the suspended solids, particularly for lipophilie compounds such as HCB and OCS,

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A Stationary Packer System for Layerwise Groundwater Sampling in Monitoring Wells – Technique and Results

Water Science & Technology ◽

10.2166/wst.1991.0454 ◽

1991 ◽

Vol 23 (1-3) ◽

pp. 545-553

Author(s):

M. Rödelsperger ◽

U. Rohmann ◽

F. Frimmel

Keyword(s):

Groundwater Discharge ◽

Groundwater Table ◽

Experimental Results ◽

Concentration Profiles ◽

Sampling Device ◽

Local Conditions ◽

Monitoring Wells ◽

Deep Aquifers ◽

Groundwater Sampling ◽

Groundwater Samples

A sampling device was designed as a stationary equipment for deep monitoring wells in order to obtain representative groundwater samples from different layers of the aquifer. The device consists of several packer units which can be combined at variable distances, allowing adaption to the local conditions of the aquifer and of the well. The pumps are situated below the groundwater table. Each of the drawing tubes ends between two packers at the concerning depth. Experimental results demonstrate the importance of the application of a stationary packer system instead of a mobile doublepacker in deep aquifers of inhomogeneous structure. Examples of concentration profiles obtained from layerwise groundwater sampling are given and a technique for selective groundwater discharge is described.

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