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通过Ｘ－射线衍射、电子显微镜、差热重量分析、表面积测定等方法，研究了合成的铝代换针铁矿加热脱水及形成赤铁矿过程中一系列矿物学性质的变化。结果表明，针铁矿的脱水温度随铝代换量增加而升高，在２７０℃加热１ｈ完全转化成赤铁矿后，仍有约５％的过量羟基保留在赤铁矿晶格中。铝代换使针铁矿晶胞变小，而过量羟基的存在使针铁矿晶胞增大，针铁矿晶胞的ａ－轴及与之相应的赤铁矿晶胞的ｃ－轴对过量羟基／水分子的影响最为敏感。针铁矿和赤铁矿的晶粒大小约在７～１０ｎｍ间，它们的比表面积随铝代换量的增加而增大。在加热过程中，表面积会因针铁矿的解体而增加，但当赤铁矿形成之后，表面积的减少则可归咎于赤铁矿晶粒的增大。
The changes of a series of mineralogical properties during the process of dehydration and hematite formation were investigated by X-ray diffraction, electron microscopy, differential thermal gravimetric analysis and surface area measurement. The results showed that the dehydration temperature of goethite increased with the increase of aluminum substitution, and about 5% of excess hydroxyl remained in the hematite crystal lattice after being completely transformed into hematite at 270 ℃ for 1 h. The aluminum substitution changed the goethite unit cell size, while the excess hydroxyl group increased the unit cell of goethite, the a-axis of the goethite unit cell and the c-axis pair of the corresponding hematite unit cell The effect of excess hydroxyl / water molecules is most sensitive. Goethite and hematite grain size of about 7 ~ 10nm, their specific surface area increases with the aluminum substitution increases. During heating, the surface area increases due to the dissolution of goethite, but the reduction of surface area after hematite formation can be attributed to the increase of hematite grains.