I have found many authors are claimed that the saturation magnetization (Ms) value of iron nanoparticle is 66.1 emu/g. Is this standard value? Is the Ms value of iron nanoparticles depend on preparation temperature?
Co-precipitation of iron oxide and particularly at nano scale may always lead to lower Ms than bulk. Reasons are mainly due to surface disorder and some modification in cationic distribution. In some cases iron hydroxide layer is also formed. This can lower Ms. There are several papers on this aspect in literature.