(a) Saturation magnetization of Fe3O4 is 5105A/m. Design a cubic mixed-ferrite magnetic material that has a saturation magnetization of 4.1105A/m. Select a cation and calculate how many of Fe+2 cations should be replaced? Hint: There are 8Fe+2 ions per unit cell. The unit cell edge length of Fe3O4 is 0.839nm 1 Bohr magneton (mB)=9.271024 A. m2 Saturation magnetisation = total number of Bohr magnetons per unit cell/volume of unit cell Table 20.4 Net Magnetic Moments for Six Cations (b) What would be the saturation magnetization if all Fe+2 cations are replaced with Zn+2 cations