Thin Films from Solvated Metal Atoms and Metal-Metal Bonded Compounds
ABSTRACT Metals such as Pd, Pt, Cu, Ag, Ga, In, Ge, Sn, and Pb are evaporated under vacuum and the vapors (atoms) condensed at 77 K with excess organic solvents. In this way solvated metal atoms are produced.. Upon warmup to room temperature metal atom agglomeration occurs in certain solvents to yield stable colloidal particles in solution. In many cases these are the first examples of non-aqueous colloids of these metals, and they are very novel in that they are free of contaminating reducing agents, halide ions, etc., and they are living colloids--by removal of solvent metallic films can be grown on various substrates under very mile conditions. Characterizing these colloidal particles and the films therefrom is an important part of this project. A second area is the proposed synthesis of new metal-metal bonded compounds, eg. R2A1-A1R2, as possible new Chemical Vapor Deposition materials for thin film production. Unusual synthetic approaches, some involving metal vapors, are underway. Compounds containing Al, Ga, In, and level, is that two metal atoms could be deposited at a time on a hot substrate target, thereby generating films of novel structure/stoichiometry (when mixed metals are being codeposited).
- High Energy Processes in Organomet. 246..
%ECU.']ITY CLASSIFICATION OF THIS PAGE (When Date Entered)
GOVT ACCESSION No. 3. RECIPIENT'S CATALOG NUMBER
TITLE (and Subtitle)
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Thin Film.,s from Metal-Metal Bonded
Compounds and Solvated Metal Atoms
PERFORMING ORG. REPORT NUMBER
CONTRACT OR GRANT NUMBER(s)
Kenneth J. Klabunde
PERFORMING ORGANIZATION NAME AND ADDRESS
Kansas State University
Department of Chemistry
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19. KEY WORDS (Continue on reverse side JInecessary and Identify by block number)
atoms, films, solvated, metal-metal bonds
20. ABSTRACT (Continue on reverse side It necessary and Identify by block numiber)
Solvated metal atoms were employed to produce non-aqueous colloidal
these were useful in preparing thin metal films in liquid
phase. Metal-metal bonded compounds were studied; synthesis from
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EDI TION OF I NOV 65 IS OBSOLETE
CLASSIFICATION OF THIS PAGE (190
A. \ Peneral Description of Research Carried Out
Metals such as Pd, Pt, Cu, Ag, Ga, In, Ge, Sn, and Pb were evaporated
under vacuum and the vapors (atoms) cocondensed at 77°K with excess organic
In this way solvated metal atoms were produced. Upon warmup to
room temperature metal atom agglomeration occurred in certain solvents to
yield stable colloidal particles in solution. In many cases these were the
first examples of non-aqueous colloids of these metals, and they are very
novel in that they are free of contaminating reducing agents, halide ions,
etc., and they are living colloids--by removal of solvent metallic films can
be grown on various substrates under very mild conditions. Characterizing
these colloidal particles and the films therefrom was an important part of
A second area was the synthesis of new metal-metal bonded compounds,
eg. R2Al-AlR2, as possible new Chemical Vapor Deposition materials for thin
film production. Unusual synthetic approaches, some involving metal vapors,
Compounds containing Al, Ga, In, and As were considered. The
advantage of such materials, on the microscopic level,
atoms could be deposited at a time on a hot substrate target, thereby
generating films of novel structure/stoichimetry (when mixed metals are
B. Brief Description of Results
Our colloid and surface work continued throughout the contract and we
have reported on Au, Pd and In colloidal dispersions in organic solvents. 0
These living colloids behave as film precursors. We spent much of the time
working with the In system and have been able to prepare and characterize In
colloidal particles in THF, DMF, isopropanol, acetone, and other organic
Films of indium metal and indium oxide were prepared and studied.
We also found that stable Au and Pd colloids could be prepared in liquid
styrene, and this purple solution could be controllably polymerized to metal
doped polystyrene. This was the first preparation of stable metal colloids
such as these in a useful monomer medium. Unusual stabilization mechanisms
for these colloidal particles are of interest:
(1) the particles appeared to scavange electrons to become negatively
must be important.
Electrophoresis studies, electron microscopy,
plasmon absorption spectroscopy, and conductivity studies were valuable in
characterization of particles and films.
A second major emphasis was the attempted synthesis of Al-Al, Al-As,
Ga-Ga, and Ga-As bonded organometallic compounds.
We met with limited
However, we further elucidated the chemistry of Al and Ga atoms,
As2 dimer. We have discovered a facile synthesis of R3Ga2X3 which may be an
important discovery since
it would allow a better route to R3Ga compounds
for CVD processes.
C. Most Recent Findings
The dispersion of metal vapor into fluorocarbon solvents has been of
in recent months.
Metal atom clustering in cold fluorocarbon
solvents occurred as in analagous hydrocarbon solvents.
did not stabilize
colloidal suspensions at room temperature, and metal
powder precipitated. However, a very interesting phenomenon is
fluorocarbon derived metal powder were "soluble" in organic solvents. A
good example is gold powder derived from perfluoro-tri-n-butylamine.
(or treatment of the filter cake) with acetone, red colloidal
suspensions were obtained. The gold particles "dissolved" in this way were
smaller than those obtained directly from metal atoms dispersed in acetone.
For example, fluorocarbon derived particles were 1O-40A, while acetone
derived were 50-90A. Furthermore, the particles retained fluorocarbon; that
is, according to X-ray fluorescence they are true gold but their surfaces
appear to be fluorocarbon coated, thus their strange molecular behavior
(ability to be dissolved and small size).
A Listing of Technical Reports Submitted
1. S. T. Lin, M. T.
Franklin, and K. J. Klabunde, "Non-Aqueous
Clustering of Metal Atoms in Organic Media, 12,"
Langmuir, 2, 259 (1986).
editor, "Thin Films From Free Atoms and
Particles," Academic Press, Orlando (1985).
3. K. J. Klabunde, "Introduction to Free Atoms and Particles," Chapter
in 2 above.
4. G. Nieman and K. J. Klabunde, "Clustering of Free Atoms and
Polymerization and Film Growth," Chapter in 2 above.
Franklin and K. J. Klabunde, Sym. High Energy Processes in
Organomet. Chem. K. Suslick, editor, ACS Sym. No. 333, pg.
6. G. Cardenas-Trivino, K. J. Klabunde, and B. Dale, Langmuir, 3, 986
7. G. Cardenas-Trivino, K. J. Klabunde, and B. Dale,
Films from Solvated Metal Atoms" Proceedings of SPIE, Vol. 821,
8. K. Starowieyski
and K. J. Klabunde, "Reactions of Vapors of Some
Metals and Metal Oxides with Organometallics of Main
Ap. Organomet. Chem., in press.
Importance of Past ONR Supported Work
The major contributions have been the discovery that colloidal metal
particles can be prepared by agglomeration of solvated metal atoms,
exploring part of the scope of this process,
learning about particle
stabilization mechanisms, and demonstrating that metal films can be prepared
from these colloidal solutions.
This work has opened up a new dimension in
colloid chemistry and potentially in thin film production.
Two of our papers
(1 and 5 above) discuss the history of colloidal
metal particles and emphasize the novelty of our discovery.
As a partial
reiteration of the reasons such colloidal solutions are unique:
(2) no metal salts reducing process is used so no
biproducts are present at impurities, (3) the metal particles are "living"
in the sense that simply by solvent removal particle growth occurs until
films result, (4) films can be deposited on irregularly shaped objects, (5)
the method allows particle deposition in polymer matrices, and (6) particle
size can be controlled by metal:
solvent ratios, solvent choice, and warm-
Industrial interest in these colloidal solutions as film precursors has
been extremely gratifying. Shortly after announcing our findings
filing for patent protection),
a series of events took place: a major
company expressed their intent to license the patent and is paying
(the P.I. is a consultant for this company); the findings were
summarized in three research and development magazines;