Microstructure of electroplated soft magnetic CoNiFe thin films

The microstructural and crystallographic characteristics of electroplated s oft magnetic CoNiFe thin films were investigated by transmission electron m icroscopy. Dark field images showed that the film with fcc-bcc dual crystal s has a smaller grain size than the fee or bcc single phase film. The fee f ilms were found to have a unique microstructure with twin-like stacking fau lts with relatively uniform grain size distribution, and such twins were al so found in the dual phase films. Some coarse grains were found in the bcc films with a twin-free microstructure. The film prepared from the thiourea bath had a smaller grain size than that of the film from the saccharin bath . It is suggested from the diffraction patterns that the fee and bcc compon ents of the films are substitutional solid solutions of Co, Ni and Fe. The lattice constants of fee CoNiFe films are determined by atomic concentratio ns of the three elements. The crystal structures of bcc films are determine d by Fe, and the lattice constants are slightly changed by the incorporatio n of Co and Ni into the bcc lattice of Fe. The CoNiFe films obtained from s accharin and thiourea baths have different lattice constants, because of di fferent sulfur contents of the films. (C) 2001 Elsevier Science B.V. All ri ghts reserved.