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..
OFFICE OF NAVAL RESEARCH
R&T Code 413a001 ---01
"Thin Films from Solvated Metal Atoms and Metal-Metal Bonded Compounds"
Kenneth J. Klabunde
Department of Chemistry
Kansas State University
Manhattan, KS 66506
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"Thin Films from Solvated Metal Atoms and
Met-al-Metal Bonded Compounds"
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Kenneth J. Klabunde
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Kansas State University
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I9. KCEY WORDS (Continuo, on reverse ad. if necessary and Identify by block number)
metal atoms, solvated, nonaqueous colloids, metal particles, clustering,
living colloids, palladium, gold, indium, thin films, chemical liquid
ABSTRACT (Continue on reverse aide if nocoo.ctV and Identify by block number)
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EDITION OF INOV 65 IS OBSOLETE-
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Metals such as Pd, Pt, Cu, Ag, Ga, In, Ge, Sn, and Pb are evaporated
under vacuum and the vapors (atoms) cocondensed 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 mild conditions.
these colloidal particles and the films therefrom is an important part of
A second area is
compounds, eg. R Al-AlR2' , as possible new Chemical Vapor
for thin film production.
involving metal vapors, are underway. Compounds containing Al, Ga, In, and
The advantage of such material, on the microscopic
level, is that two metal atoms could be deposited at a time on a hot
structure/stoichiometry (when mixed metals are being codeposited).
the proposed synthesis of new metal-metal bonded
Unusual synthetic approaches, some
Brief Description of Results
Our colloid and surface work continued and we have reported on Au, Pd,
and In colloidal dispersions in organic solvents.
indium oxide were prepared and studied. We also found that stable Au and Pd
colloids can be prepared in liquid styrene, and this purple solution can be
controllably polymerized to metal doped polystyrene.
preparation of stable metal colloids such as these in a useful monomer
medium. Unusual stabilization mechanisms for these colloidal particles
Films of indium metal and
(1) the particles appear to scavenge electrons to become negatively
Electrophoresis studies, electron microscopy,
plasmon absorption spectroscopy, and conductivity studies have been valuable
in characterization of particles and films.
A second major emphasis this year has been the attempted synthesis of
Al-Al, Al-As, Ga-Ga, and Ga-As bonded organometallic compounds. We have met
with limited success. However, we have further elucidated the chemistry of
Al and Ga atoms, and As dimer. We have discovered a facile synthesis of
R Ga 2X
which may be an important discovery since it would allow a better
route o R 3Ga compounds for CVD processes.
must be important.
B. Recent Findings (July 1987 to July 1988)
The dispersion of metal vapor into fluorocarbon solvents has been of
interest in recent months. Metal atom clustering in cold fluorocarbons do
not stabilize colloidal suspensions at room temperature, and metal powder
fluorocarbon derived metal powder are "soluble" in organic solvents. A good
is gold powder derived from perfluoro-tri-n-butylamine.
extraction (or treatment of the filter cake) with acetone, red colloidal
suspensions are obtained.
The gold particles "dissolved" in this way are
smaller than those obtained directly from metal atoms dispersed in acetone.
How-ver, a very interesting phenomenon is
For example, fluorocarbon derived particles are
derived are 50-90A. Furthermore, the particles retain fluorocarbon;
according to X-ray fluorescence they are true gold but their surfaces
appear to be fluorocarbon coated, thus
(ability to be dissolved and small size).
10-40A, while acetone
their strange molecular behavior
We have also discovered that
methylmethacrylate can stabilize colloidal dispersions of Cu, Ag, Au, and
Pd. Polymerization of these colored solutions yields homogeneous metal
This procedure works extremely well and allows the
synthesis of various loadings of metal doped polymers.
C. A Listing of Technical Reports Submitted
1. S. T. Lin, M. T. Franklin, and K. J. Klabunde, "Non-Aqueous Colloidal
Clustering of Metal Atoms in Organic Media, 12," Langmuir, 2,
2. K. J. Klabunde, 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
4. G. Nieman and K. J. Klabunde, "Clustering of Free Atoms and Particles:
Polymerization and Film Growth," Chapter in 2 above.
5. M. Franklin and K. J. Klabunde, "Living Colloidal Metal Particles from
Solvated Metal Atoms:
Clustering of Metal Atoms in Organic Media",
Sym. High Energy Processes in Organomet. Chem., K. Suslick, editor, ACS
Sym. No. 333, pg. 246 (1987).
Cardenas-Trivino, K. J. Klabunde, and B. Dale, "Living Colloidal
Palladium in Non-Aqueous Solvents.
Forming Properties. Clustering of Metal Atoms in Organic Media. 14",
Langmuir, 3, 986 (1987).
Formation, Stability and Film
Cardenas-Trivino, K. J. Klabunde, and B. Dale, "Thin Metallic Films
from Solvated Metal Atoms", Proceedings of SPIE, Vol. 821, 206 (1987).
8. K. Starowieyski and K. J. Klabunde, "Reactions of Vapors of Some Metals
and Metal Oxides with Organometallics of Main Group
Submitted to App, Organomet, Chem,
9. G. Cardenas-Trivino and K. J. Klabunde, "Characterization of Metallic
Thin Films Prepared by Chemical Liquid Deposition (CLD):
Colloidal Metal Particles in Non-Aqueous Solvents",
Chemical Society of Chile, in press.
Journal of the
G. Cardenas-Trivino and K. J. Klabunde, "Thermal Degradation Studies
and Scanning Electron Microscopy Studies of Pd Thin Films", XVIII
Latin-American Chemical Congress, Santiago, Chile, January 1988.
G. Cardenas-Trivino and K. J. Klabunde, "Synthesis, Stability, and
Structure of Metal Colloidal Dispersions in Non-Aqueous Solvents",
XVIII Latin-American Chemical Congress, Santiago, Chile, January 1988.
12. J. Habdas and K. J. Klabunde, "Preparation of Colloidal Au, Ag, Pd, and
Cu in Styrene, Polystyrene, Methylacrylate and Polymethylacrylate", to
be submitted to Macromolecules.
13. E. Zuckerman and K. J. Klabunde, "Metal Clusters or Metal Colloids?"
Clustering of Metal Atoms in Fluorocarbon Media."
Chemistry of Materials.
D. 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.
The attached reprints (two of thirteen technical reports)1 '
the history of colloidal metal particles and emphasize the novelty of our
discovery. As a partial reiteration of the reasons such colloidal solutions
(1) they are non-aqueous, (2) no metal salts reducing process
is used so no biproducts are present as 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 inn polymer matrices, and
(6) particle size can be controlled by metal: solvent ratios, solvent
choice, and warm-up procedures.
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 has expressed their interest to license the patent and is paying the
patent fees (the P. I. is a consultant for this company)4 the findings were
summarized in three research and development magazines;
invited to speak at an international meeting of optical engineers (SPIE
meeting in San Diego); reprint requests have been numerous; phone calls and
letters from numerous industrial firms requesting more information and
samples were received (the names of these forms can be provided on a
the P. I. was
The firms interested in this technology invariably wanted to know if we
could produce films on irregularly shaped objects such as metal parts,
screens, and fabrics.
Often such substrates cannot
conventional vacuum evaporation/deposition methods. Another general theme
was the need to deposit metal particles on or in composite materials or
organic polymers. These and other interactions convince us that the work we
are doing is certain to be useful to many high technology companies.
(These same scientists have expressed considerable general interes in
a book the P. I. edited on "Thin Films from Free Atoms" and Particles.")