MAGNETIC CHARACTERIZATION OF CALCIUM-NICKEL-POTASSIUM OXIDE CATALYSTS

SQUID magnetometer characterization of Ca-Ni-K-O catalyst materials re veals complex magnetic behavior. The magnetic properties are generally determined by the antiferromagnetic material NiO, but samples with tr aces of elemental nickel show marked effects of ferromagnetism. Potass ium doping enhances the formation of metallic nickel. Further deviatio ns from bulk NiO properties can be attributed to NiO particle size eff ects (superparamagnetism) and to the presence of paramagnetic impuriti es, possibly Ni3+ ions.