magnetization was 45.0 Am2/kg at μ0H=7 T. Fig. 7 shows the unit cell of Sr2Fe2Y-type hexaferrite and the expected spin configuration. Since the unit cell is represented by stacking of [TS], the [TS] part alone is sufficient for the consideration of the spin configuration, corresponding to the chemical formula of Sr2Fe2Y-type hexaferrite. There are fourteen iron ions (Fe2+, Fe3+) per chemical formula of Fe2Y-type hexaferrite. In the formula unit of Fe2Y-type hexaferrite, there are ten octahedral sites and four tetrahedral sites. The model of collinear magnetic structure assumes that the magnetic moments of cations are arranged in up and down directions. Spin-down cations are located at two octahedral sites in the T-block and at four tetrahedral sites in the Sand T-blocks. Spin-up cations are at the other eight octahedral sites in the Y-type structure. Since Fe2+ ions with the magnetic moment of 4 μB are considered to occupy the spin-up octahedral sites in the S-block and Fe3+ ions with the magnetic moment of 5 μB at the other sites, the Fe2Y-type hexaferrite has the magnetic moment of 8 μB per formula unit. This value corresponds to 34.1 Am2/kg (=MY), which is smaller than the observed experimental value of 45.0 Am2/kg (=Mobserved). This was affected by the co-existence of Sr2Fe2Y and Fe3O4-like spinel. The difference in magnetization with (Mobserved − MY)/Mobserved is about 3/4. This difference is consistent with the two-step decreases of magnetization shown in Fig. 5. Here, we let x be the mass fraction of Sr2Fe2Y in the sample with Sr:Fe2+:Fe3+=1.5:2:8 sintered at TS=1200°C and PPPPO2�����=10 Pa, ignoring the small amounts of Sr7Fe10O22 and the unknown Sr-rich phases. The observed magnetization can be explained by the use of the spontaneous magnetization of Fe3O4 (98 Am2/kg) as following: 34.1 × xxxx + 98 × (1 − xxxx) = 45.0 . This equation gives the mass fraction x as 0.83. By the use of CRYSTALDIFFRACT, on the other hand, we simulated diffraction patterns of the mixture of Sr2Fe2Y and Fe3O4 around 0.83<x<0.9 that were similar to the experimental pattern in Fig. 3 although the complex crystal structure and the preferential orientation hindered the precise estimation of the amount of Sr2Fe2Y phase from the X-ray diffraction experiments. Therefore, we successfully synthesized Sr2Fe2Y with the yield of about 83 wt. %.