Effect of Bi2O3 doping on the Curie temperature, Q factor and linear shrinkage of Mn-Zn ferrites

Bi2O3 was added to the Mn-Zn ferrite (52 mol % Fe2O3, 34 mol% MnO, 14 mol% ZnO) in the amounts of 0.03, 0.08, 0.2, 1 and 5 wt%. Q factor, Curie temperature and linear shrinkage were investigated. Several sintering conditions were practiced. The optimum sintering condition (1200 °C for 1 hour) was determined based on the maximum value of the Q factor of undoped ferrite. The net magnetic moment, Curie point and shrinkage behavior of the material were influenced by Bi2O3. Results showed that in small additions of Bi2O3 (0.03 wt %), the Q factor was the maximum, and with increasing Bi2O3, the linear shrinkage decreased. The Curie temperature changed in two stages; it increased in the first where Bi2O3 was below 1 wt%, and then decreased above this value.