Infrared spectroscopic study of OH defects in monazite
Infrared spectroscopic study of OH defects in monazite
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独居石中OH缺陷的红外光谱研究
DOI：
10.1127/ejm/2017/0029-2663
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Michihiko Nakamura
中科院分区：
文献类型：
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作者：
Takeyasu Abe;Takahiro Kuribahyashi;Michihiko Nakamura
收集了合成单晶和辐射损伤天然样品的偏振红外光谱，以检查独居石中的羟基掺入。纯合成独居石的红外光谱在3163和3335 cm− 1处包含两个OH伸缩带，其对比带宽分别为40和90 cm−1。两个OH带具有很强的多色性，在Y方向有明显的红外吸收。天然独居石的红外光谱包含一个弱的多色性OH带，中心在3400 cm− 1附近，带宽超过200 cm−1。在逐步加热实验中，这个宽的OH带分裂成几个带，这些带与合成样品光谱中观察到的带不同。在1000 °C加热后，天然和合成样品光谱中的OH伸缩信号消失。从红外吸收推断的H2O浓度在合成独居石中为22（2）ppm，在天然样品中为130-520 ppm。这些结果表明，在天然独居石的OH缺陷出现，因为二次水化促进辐射损伤，在天然锆石和磷钇矿的情况下。
Polarised infrared spectra of synthetic single crystals and radiation-damaged natural samples were collected to examine hydroxyl incorporation in monazite. The IR spectra of pure synthetic monazite contain two OH stretching bands at 3163 and ∼3335 cm−1with contrasting bandwidths of ∼40 and ∼90 cm−1, respectively. The two OH bands show strong pleochroism and dominant infrared absorption in theYdirection. The IR spectra of natural monazite contain a weak pleochroic OH band centred around 3400 cm−1with a bandwidth of more than 200 cm−1. During step-heating experiments, this broad OH band split into several bands, and these bands differ from those observed in the spectra of synthetic samples. The OH stretching signals in the spectra of both natural and synthetic samples disappeared after heating at 1000 °C. The H2O concentration inferred from the infrared absorbance was 22(2) ppm in the synthetic monazite and 130–520 ppm in the natural samples. These results suggest that OH defects in natural monazite arise because of secondary hydration facilitated by radiation damage, as in the case of natural zircon and xenotime.