A new approach to the synthesis of intermetallic compounds: mild synthesis of submicrometric CoxMy (M = Mo, W; x∶y = 3∶1 and 7∶6) particles by direct reduction of freeze-dried precursors

Abstract

A simple processing route to cobalt–molybdenum and cobalt–tungsten intermetallics (CoxMy, where M = Mo and W, and x∶y = 3∶1 and 7∶6) has been developed, on the basis of the use of precursors resulting from freeze-drying of aqueous solutions of the appropriate common metal salts. The influence of the preparative variables on the outcomes of this procedure is examined. These compounds are prepared as single phases by thermal reduction of amorphous freeze-dried powders under a hydrogen–argon atmosphere (8% H2), followed by slow cooling of the samples. The materials have been characterised by X-ray powder diffraction, metal analysis, scanning electron microscopy and thermogravimetry under an oxygen flow. CoxMoy and CoxWy grains are aggregates of submicrometric spherical particles.