Abstract: The invention relates to visible-laser deposition reactions of metal containing oxyhalide vapors, such as, chromyl chloride vapor, CrO.sub.2 Cl.sub.2, for direct writing of metal containing opaque oxide patterns on various substrates (S.sub.i, S.sub.i O.sub.2, GaAs and glass). Deposition at low laser power is by photolyses of adsorbed reactant molecules. Higher powers initiate deposition photochemically and continue it with a combined photolytic/pyrolytic reaction, simultaneously inducing a solid-phase conversion of the deposited film. Mixed Cr.sub.2 O.sub.3 /CrO.sub.2 thin films of 1-nanometer to several-micrometer thickness, as well as 1-millimeter-long single crystals of Cr.sub.2 O.sub.3, can be grown with this process, the latter at rates up to 3 .mu.m/s. Thin chromium oxide films produced in this manner are strongly ferromagnetic. Mass spectrometer and optical transmission measurements show that surface kinetics dominate the nucleation and growth rates.