Analysis of power loss in Ni-Cu-Zn ferrites

The power loss analysis was carried out for Ni-Cu-Zn ferrite samples with different content of NiO and ZnO. The power loss, Pcν decreases monotonically with increasing temperature and attains to a certain value at around 100∼120 degrees Celsius. The frequency dependence of Pcν can be explained by Pcν∼f, and n is independent of the frequency, f up to 1 MHz. The Pcν decreases with an increase in ZnO/NiO. The Pcν was separated to hysteresis loss, Ph and residual loss, (Pcν-Ph). The temperature characteristics and compositional dependence of Pcν can be attributed to the Ph, while (Pcν-Ph) is not affected by both temperature and ZnO/NiO. By analyzing temperature and composition dependence of Ph and initial permeability, u_i following equations could be formularized. u_iu₀ = I_s²/(K_I + bs₀l_s) (1), Wh = 13.5(I_s²/u_iu₀) (2), where u₀ is permeability of vacuum, I_s saturation magnetization, K_I anisotropy constant, s₀ internal heterogeneous stress, l_s magnetostriction constant, b unknown constant. Wh hysteresis loss per one cycle of excitation (Ph = Wh*f). Steinmetz constant of Ni-Cu-Zn ferrites, m = 1.64∼2.2 is smaller than the one of Mn-Zn ferrites, which suggests the difference of loss mechanism between these materials.