ゾル-ゲル法によるリチウムフェライト粉体の磁気特性

概要

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Amorphous gel powders were prepared by heating an ethylene glycol solution containing Fe(NO_3)_3・9H_2O and LiNO_3 (Li/Fe (in molar ratio) = 0-0.31) at 353 K under a N_2 flow. The powders without lithium crystallized to γ-Fe_2O_3 at 573 K and to α-Fe_2O_3 above 773 K. On annealing the powders of Li/Fe = 0.18-0.31, a LiFe_5O_8-type phase appeared at 573 K which coexisted with α-Fe_2O_3 at above 673 K. The LiFe_5O_8-type phase without α-Fe_2O_3 could only be obtained on annealing the powder of Li/Fe =0.31 at 973 K for 2h. The saturation magnetization of the powder was 0.29 T (74% of LiFe_5O_8) and its coercive force was 10.5 kA・m^<-1>. With increasing crystallite size of the LiFe_5O_8-type phase, the coercive force of the powder increased until equal to 13.2 kA・m^<-1> and then decreased. The estimated maximum single magnetic domain size was 40-50 nm.
社団法人日本セラミックス協会の論文
1998-06-01