  Fe2O3 nanoparticles of different sizes ranging from 22 to 56nm were
synthesized chemically by a modified sol-gel method. Pure alpha phase particles
as well as particles with admixture of alpha and gamma phase were obtained and
identified by x-ray and M\"ossbauer measurements. Different size and phase
controlling parameters have been identified. The average size of the particles
decreases with increased annealing temperature of the gel and decreases with
the increase in the concentrations of the (citric acid). The annealing
temperature affects the relative fractions of the two phases and consequently
the magnetization of the particles. The magnetization of the particles (Ms) and
coercivity (Hc) increase consistently with the increase in the annealing
temperature. For the same relative amount of the two phases, the coercivity
(Hc) and the moment of the particles increase with the decrease in the size of
the particles, indicating the role of surface effects in the magnetic
behaviour.
