The ensemble properties of comets: Results from narrowband photometry of 85 comets

A process for producing novel air-stable coated particles of a magnetic transition metal-rare earth alloy. An organometallic compound which decomposes at a temperature below 500 DEG C is heated to produce a metal vapor which is contacted with particles of a transition metal-rare earth alloy to deposit a metal coating thereon. The coated particles are heated at a temperature ranging from 50 DEG C to 200 DEG C for a period of time sufficient to increase their intrinsic coercive force by at least 10 percent.