Ruan H D, Frost R L, Kloprogge J T
Centre for Instrumental and Developmental Chemistry, Queensland University of Technology, Brisbane, Australia.
Spectrochim Acta A Mol Biomol Spectrosc. 2001 Nov;57(13):2575-86. doi: 10.1016/s1386-1425(01)00445-0.
The behavior of the hydroxyl units of synthetic goethite and its dehydroxylated product hematite was characterized using a combination of Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) during the thermal transformation over a temperature range of 180-270 degrees C. Hematite was detected at temperatures above 200 degrees C by XRD while goethite was not observed above 230 degrees C. Five intense OH vibrations at 3212-3194, 1687-1674, 1643-1640, 888-884 and 800-798 cm(-1), and a H2O vibration at 3450-3445 cm(-1) were observed for goethite. The intensity of hydroxyl stretching and bending vibrations decreased with the extent of dehydroxylation of goethite. Infrared absorption bands clearly show the phase transformation between goethite and hematite: in particular. the migration of excess hydroxyl units from goethite to hematite. Two bands at 536-533 and 454-452 cm(-1) are the low wavenumber vibrations of Fe-O in the hematite structure. Band component analysis data of FTIR spectra support the fact that the hydroxyl units mainly affect the a plane in goethite and the equivalent c plane in hematite.
在180-270摄氏度的温度范围内进行热转变过程中，结合傅里叶变换红外光谱（FTIR）和X射线衍射（XRD）对合成针铁矿及其脱羟基产物赤铁矿的羟基单元行为进行了表征。通过XRD在200摄氏度以上的温度检测到了赤铁矿，而在230摄氏度以上未观察到针铁矿。针铁矿观察到五个在3212-3194、1687-1674、1643-1640、888-884和800-798 cm-1处的强OH振动，以及一个在3450-3445 cm-1处的H2O振动。针铁矿的羟基伸缩和弯曲振动强度随着脱羟基程度的增加而降低。红外吸收带清楚地显示了针铁矿和赤铁矿之间的相变：特别是，过量的羟基单元从针铁矿迁移到赤铁矿。在536-533和454-452 cm-1处的两个谱带是赤铁矿结构中Fe-O的低波数振动。FTIR光谱的谱带成分分析数据支持羟基单元主要影响针铁矿中的a平面和赤铁矿中等效的c平面这一事实。
