Abstract: A dust core that can significantly reduce the iron loss is provided. The dust core of the present invention includes soft magnetic particles comprising pure iron or an iron alloy and a grain boundary layer existing between adjacent soft magnetic particles. The grain boundary layer has a compound layer comprising MxFe2-xSiO4 (0?x?1, M: one or more types of metal elements that serve as divalent cations). Such a dust core is obtained by annealing a compact. The compact is obtained by compression-molding a powder for magnetic cores. In the powder for magnetic cores, coating layers that coat the surfaces of soft magnetic particles are each composed of a composite phase in which spinel-type ferrite represented by MyFe3-yO4 (0?y?1, M: one or more types of metal elements that serve as divalent cations) is dispersed on a surface of a silicone resin or inside the silicone resin.

Abstract: A powder for dust core used for a dust core includes a plurality of crystal grains, and the powder has at least two maximal values when a number ratio that is a ratio of the number of the crystal grains at each crystal grain diameter to the number of the crystal grains each crystal grain diameter of which has been measured is plotted with respect to each crystal grain diameter of the crystal grains.

Abstract: A dust core that can significantly reduce the iron loss is provided. The dust core of the present invention includes soft magnetic particles comprising pure iron or an iron alloy and a grain boundary layer existing between adjacent soft magnetic particles. The grain boundary layer has a compound layer comprising MxFe2-xSiO4 (0?x?1, M: one or more types of metal elements that serve as divalent cations). Such a dust core is obtained by annealing a compact. The compact is obtained by compression-molding a powder for magnetic cores. In the powder for magnetic cores, coating layers that coat the surfaces of soft magnetic particles are each composed of a composite phase in which spinel-type ferrite represented by MyFe3-yO4 (0?y?1, M: one or more types of metal elements that serve as divalent cations) is dispersed on a surface of a silicone resin or inside the silicone resin.

Abstract: A powder for dust core used for a dust core includes a plurality of crystal grains, and the powder has at least two maximal values when a number ratio that is a ratio of the number of the crystal grains at each crystal grain diameter to the number of the crystal grains each crystal grain diameter of which has been measured is plotted with respect to each crystal grain diameter of the crystal grains.