Please read this and my other puplication about same topic u can get som idea about it sir and commercial method also

Article Preparation and Characterization of Mg Doped γ-Fe2o3 Prepare...

there are at least two possible ways to get oxide from Cl-ides, its up to you to choose, particularly you can use solution combustion method (technically it contains the following steps: dissolving in water, adding some Nitrates and fuel e.g. urea or any other one, drying all mixture and firing, and finally heat treating), or the other way is co-precipitation method (technically it means dissolving in water, precipitating in the form of carbonates with ammonium carbonate, formation of Sn carbonate or hydroxide should be preliminary checked to make sure that it will be precipitated, filtering, washing, drying and finally heat treating). 

Coprecipitation is a technique that will produce powders with a good interdispersion of the various elements. Besides that, it is possible to obtain single phases containing all the active elements due to an intimate mixing which is guaranteed by the method. But, you'll need to avoid consecutive precipitation of Sn and Fe ions in order to obtain those characteristics. To guarantee simultaneous precipitation of metal ions you should (i) check their values of precipitation pH, (ii) adjust the correct amount of base solution and (iii) reverse the mixing order, i.e. to add the chlorides solution into the base solution. Hope it can help you!

good details from Guilherme Luís Cordeiro. thanks.

treat .1 molar  iron chloride with .1 molar sodium hydroxide which will result in iron hydroxide and sodium chloride. cook this in hydrothermal apparatus at 150 degree centigrade for one hour. allow it to cool to room temperature slowly.take the powder in the bottom. it will  be your thing and then heat it outside so as to complete the formation