JOURNAL OF SOLID STATE CHEMISTRY 39, 298-308 (1981) Mechanism of Ni-Zn Ferrite Formation V. V. PAN’KOV AND L. A. BASHKIROV Institute of Solid State Physics and Semiconductors, Byelorussian Academy Of Sciences, Minsk, Podlesnaya 17, 220726 USSR Received June 2$ 1980; in revised form April 30, 1981 The regularities in the change of character of the ferrite formation process as a function of Ni,-,Zn,Fe,O, solid solution and of the degree of zinc oxide saturation of the Ni,-,Zn=O solid solution (x = 0.14; 0.29; 0.43) are established in the temperature range 1220-1305°C. It is shown that in the reaction zone of interacting NiO, (Ni, ZnO), or ZnO with FelOJ the ferrite phase crystallizes only on iron oxide. The distribution of the Fe, Ni, and Zn concentrations over the reaction layer thickness using electron probe and X-ray spectrum analysis is obtained. The interdiffusion coefficients over the investigated temperature range calculated in the (Ni, Zn, Fe)0 and ferrite phases change from (0.8 - 7.0) x 1OP to (1.0 - 12.0) x lo-‘” cm*/sec, respectively. The interaction of (Ni, Zn)O with Fe4 takes place by the mechanism of interaction of interdiffusion of Fe3+, Fee+ and NP, Zn*+ along with a current of ZIP ions and electrons or oxygen ions directed to the ferrite/F@03 interface. Introduction In preparing Ni-Zn ferrites by the ce- ramic method from the oxide mixtures of NiO, ZnO, Fe24 the ferrite formation process is carried out by a series of inter- mediate solid solution transformations (I). One of these stages is the interaction be- tween the (Ni, Zn)O solid solution and iron oxide, formed as a result of direct interac- tion of NiO with ZnO as well as by the reaction of ZnFe,O, + NiO + (Ni, Zn) FQO, + (Ni, Zn)O (2). Sometimes the Ni- Zn ferrites synthesis is carried out by the annealing of NiCO, ZnO, FqO, mixtures. However, the nickel carbonate decomposi- tion in them precedes the ferrite formation process (3). It is possible that in this case as well one of the Ni-Zn ferrite synthesis stages is the interaction of F&O3 with solid solution (Ni, Zn)O, the formation of which due to higher activity of NiO can proceed at a higher rate than that in the mixtures of the initial oxides NiO, ZnO, Fe203. While studying this reaction for the (Ni, Zn)O solid solution with different zinc quantities one can see the change of the ferrite forma- tion mechanism on passing from nickel ferrite to zinc ferrite. With this aim in view the interaction of the coagulated pellets of FqO, with NiO, ZnO pellets and (Ni, Zn)O solid solutions, containing 14, 29, and 43 mole% of ZnO are investigated in this paper. Experimental 0022-4596/81/12029&11$02.00/0 Copy&t @ 1981 by Academic F’rem, Inc. AU rights of reproduction in any form reserved. 298 The (Ni, Zn)O solid solution powders were obtained by the coprecipitation method. These powders as well as those of NiO, ZnO, and FqO, were pressed under pressure of 1.5 x 102 MPa into pellets (10 mm in diameter and 5-6 mm in height). The annealing of the pellets was carried out in