2002 Volume 26 Issue 4 Pages 475-478
Ni-Zn ferrite films 0.2-1.2 μm in thickness were prepared by spraying a reaction solution of FeCl2(+FeCl3)+NiCl2+ZnCl2 (pH = 6.95) and an oxidizing solution of NaNO2 + CH3COONH4 (+NH3) simultaneously onto spinning glass substrates at a substrate temperature of 90°C. Films with a thickness of 0.48 μm deposited by the conventional spin-spray method using only Fe2+ as iron ions exhibited a high permeability μ' of 42 and a high magnetic resonance frequency fr of 650 MHz. This was 5 times as high as the value for Ni-Zn ferrite bulk. Film plated by adding NH3 to an oxidizing solution and film deposited by using a mixture of Fe3+(10%) and Fe2+(90%) as iron ions exhibited higher fr values of 900 MHz and 1.2 GHz, respectively. Since not only the real part μ' but also the imaginary part μ'' had large values of about 30 at 1 GHz, the films prepared in this study will be applicable to rf inductors as well as wave absorbers for suppressing EMI in the quasi-microwave range exceeding 1 GHz.
