  Half-Heusler compounds with 18 valence electrons are semi-conducting. It will
be shown that doping with electrons results in half-metallic ferromagnets,
similar to the case of diluted semi-conductors. CoTiSb is known to be a
semi-conducting Half-Heusler compound. Doping by Fe is expected to result in
ferromagnetic order. It was found that Ti can be replaced by up to about 10% Fe
while its crystal structure still remains C1b, which was proved by X-ray powder
diffraction. SQUID magnetometry revealed a magnetic moment of 0.32 mB per unit
cell at 5K.
