Mixed Metal Organometallic Clusters: Precursors for Intermetallic Powders
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MIXED METAL ORGANOMETALLIC INTERMETALLICCLUSTERS: POWDERS PRECURSORS FOR K.E. GONSALVES AND K.T. KEMBAIYAN Department of Chemistry and Chemical Engineering, Technology, Hoboken, New Jersey 07030
Stevens Institute of
ABSTRACT
Iron-cobalt organometallic clusters were pyrolyzed and yielded Fe-Co intermetallic powders. These materials were characterized by SEM-EDAX.
INTRODUCTION Transition-metal cluster compounds have been under scrutiny for their potential catalytic applications [l]. Also, in non-catalytic areas, there is a move to build alloy powders from large metal clusters [2]. Therefore, we have initiated a program to develop intermetallic powders from mixedmetal organometallic precursors [3]. Here we report the synthesis and characterization of iron-cobalt intermetallic powders obtained from heteroorganometallic clusters [4]. Our objective therefore is to (!) provide a simple and effective means of synthesizing iron-cobalt intermetallics (2) vary the ratio of iron to cobalt in such intermetallics, and (3) provide a method to produce homogeneous products from iron-cobalt metalorganic precursors specifically synthesized for this purpose. The resulting intermetallics may have unique magnetic characteristics.
EXPERIMENTAL Materials and Equipment All reactions were conducted in argon, using Schlenk techniques. In all the synthesis the apparatus was freshly assembled immediately after removal from the hot oven and subjected to repeated evacuation and purging by argon. Prepurified argon gas (Matheson) was dried over concentrated sulfuric acid and phosphorus pentoxide. Residual oxygen was removed by a BASF deoxygenation catalyst. Reagent grade acetone was also further purified by refluxing with successive small quantities of potassium permanganate until the violet color persisted. It was then dried with anhydrous calcium sulfate, filtered from the dessicant and fractionated under argon. The center cut was collected for subsequent use. Distilled water was deoxygenated by boiling for lO hours, followed by cooling under an argon stream. Infra-red spectra were recorded on a Perkin Elmer 983 spectrometer interfaced with a data station. ]H NMR spectra were recorded on a 200 MHz Bruker spectrometer. Pyrolyses were conducted in a quartz combustion tube in a tube furnace (Lindberg Model 54253) interfaced with a Eurotherm model 810 microprocessor controller. All X-ray powder diffraction measurements were carried out by means of a General Electric Diffractometer
[3].
The characterization of powders was carried out primarily by means of a high resolution scanning electron microscope (JEOL-JSM 840) which enables morphological observations of microstructures and elemental analysis. The particle size, distribution and morphology were studied by secondary elec-
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tron mode. Standardless semi-quantitative analysis was performed by means of a computer-controlled EDAX system. Several measurements were made at low magnification (
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