Achieving suitable magnetic properties in ceramic ferrites through thermomechanical treatments rather than through varying the processing and fabrication parameters alone are investigated. The high temperature phase transformation in lithium ferrite ( LiFe 5 O 8 ) spinel and the defects in LiFe 5 O 8 and NiFe 2 O 4 are studied using high voltage transmission electron microscopy in an effort to characterize the microstructures. Results show that a dispersion of paramagnetic LiFeO 2 particles in LiFe 5 O 8 matrix gives rise to increased squareness of the hysteresis curve and increased coercivity. Annealing treatments of sintered ferrites remove undesirable intra‐granular {100}1/4〈110〉 cation stacking faults and improve hysteresis loop parameters.