MICROWAVE DIELECTRIC LOSS REDUCTION BY VACUUM TREATMENT FOR (NI,ZN,FE)(3)O-4 FILMS PREPARED BY FERRITE PLATING

Films (similar to 0.5 mu m thick) of Ni0.3Zn0.4Fe2.3O4 were deposited on BN substrates by spin spray ferrite plating from an aqueous solutio n at 97 degrees C. Exposing the films to vacuum (similar to 0.01Torr) for 5 hrs at room temperature reduced their dielectric losses, tan del ta, from similar to 0.005 (including losses in the BN substrates) to s imilar to 0.002, a value which is indistinguishable from the loss in t he substrates. Annealing the films at 300 degrees C in air for 2hrs al so decreased the losses in a similar way, which, however, deteriorated the magnetic characteristics (saturation magnetization, coercive forc e, and FMR line width) of the films. On the contrary, the vacuum treat ment did not deteriorate the magnetic properties at all. The dielectri c loss was improved probably because the OH group trapped in the films from the aqueous solution were desorbed by the vacuum or the heat.