Enhanced High‐Frequency Properties of NiZn Ferrite Ceramic with Co 2 Z ‐Hexaferrite Addition

Significantly enhanced dielectric and loss characteristics have been observed in Ni 0.4 Zn 0.6 Fe 2 O 4 ferrite with various Ba 3 Co 2 Fe 24 O 41 ( Co 2 Z ) addition ( x ). Compared with pure NiZn and Co 2 Z ferrites, the composite ceramics obtain much refined grains and notable high‐frequency characteristics. With the introduction of Co 2 Z into NiZn ferrite matrix, the resistivity is largely increased from the order of 10 6  Ω cm to the order of 10 8  Ω cm and the frequency stability of permittivity is dramatically enhanced. Co 2 Z addition obviously improves the magnetic quality factor Q and reduces the dielectric loss of the ceramics at high frequency. For the samples with x  =   20−30 wt%, permittivity ε′ is almost unchanged from 1 MHz to 1 GHz, Q is greater than 10 in a wide frequency range, and dielectric loss tan δ ε is observed to be of the order of 10 −3 at 100 MHz, which is lower by two orders of magnitude compared with pure NiZn and Co 2 Z ferrites. These characteristics are all desirable for magneto‐dielectric ferrites in high‐frequency applications.