Effects of Bi2O3–CaCu3Ti4O12 composite additives on micromorphology, static magnetic properties, and FMR linewidth ΔH of NCZ ferrites. Issue 7 (May 2020) - Guo, Rongdi
Abstract: NiCuZn (NCZ) ferrites have been widely used in non-reciprocal microwave/millimeter ferrite devices, such as circulators. With the development of microwave/millimeter devices and components to high frequency, miniaturization, and lightweight applications, NCZ ferrites have needed to satisfy the essential requirements of high saturation magnetization 4π M s, low coercivity H c, and low ferromagnetic resonance (FMR) linewidth Δ H . Herein, 0.1 wt% Bi2 O3 and 0.0–3.5 wt% CaCu3 Ti4 O12 (CCTO) composite additives were introduced to NCZ ferrites, the influence of Bi2 O3 –CCTO composite additives on micromorphology, static magnetic properties, and FMR linewidth Δ H of NCZ ferrites have been demonstrated in detail. The results show that increasing the CCTO amounts in NCZ ferrites, saturation magnetization 4π M s monotonically decreases from 5484Gs to 4819Gs, and both coercive force H c and FMR linewidth Δ H first decreases and then increases with minimums of 31A/m and 147Oe, respectively. In addition, the theory of spin-wave narrowing and the law of approach to saturation have been adopted for the separation calculation of FMR linewidth Δ H to the crystalline anisotropy linewidth Δ H a and porosity induced linewidth Δ H p . The sample with 0.1 wt% Bi2 O3 and 1.5 wt% CCTO possesses high saturation magnetization 4π M s (5321Gs), remanence B r (200 mT), low coercivity H c (31A/m), and low FMR linewidth Δ H (147Oe). The state-of-the-art NCZ ferrites with outstanding performances manifest significant applied potency for microwave/millimeter devices and components in phase array radar systems.