Development of x-ray diffractometer for petrographic thin section

本研究的目的是建立一种在光学显微镜下精确检查过的岩石薄片上收集小单晶x射线衍射数据的方法。2005年，新设计的准直器将入射x射线聚焦在商用衍射仪的共同中心或phi-和chi-圆上，并已被证实工作成功。2006年，我们利用上述衍射仪配准直仪，采集了巴西Pocos de Caldas的一颗碱角闪孔晶体的x射线衍射数据，该数据发表在《矿物岩石科学杂志》2004年第99卷第59-66页。x射线数据通常是从相关材料的孤立颗粒中收集的，因此没有必要考虑入射射线的宽度。然而，薄片上的晶粒不是孤立的，而是周围有邻近的晶体…为了避免来自邻近颗粒的额外反射光束，应利用聚焦光线。为此，使用0.2mm φ的柔性硅玻璃管制作了准直器，并对该准直器进行了调焦。通常情况下，通过改变入射x射线和衍射x射线的方向来收集单晶的一整套x射线衍射数据。然而，在这种情况下，这些射线的方向是非常有限的，因为试样下面的玻片阻止了x射线的传播。为了克服这些限制，一位作者和他的同事开发了一种方法，该方法在Rigaku Denki Journal， Vol.25, Part1, pp3-9（1994）中有所描述。根据该方法，具有连续能谱的白色x射线作为入射射线，固体探测器能够分辨出衍射x射线的能量。在倒数空间内的测量范围选择在一个轴线垂直于薄片表面，垂直角度为21度的圆锥体的内部。该范围被划分为12227个小区域，每个区域的衍射x射线被计数。从相关区域获得了1540个显著的衍射强度。在薄片上，晶体中似乎保留着很大的应力场。测量数据的分析应在不久的将来进行

The purpose of this investigation is to establish a method of a collection of x-ray diffraction data from a small single crystal on the petrographic thin section which has been examined precisely under the optical microscope.In 2005, the collimator by which incident x-rays were focused on the common center or phi- and chi-circle of a comercial diffractometer was newly designed and has been confirmed to work successfully.In 2006, the x-ray diffraction data from a small grain of an alkali amphibole crystal on the thin section of nepheime syenite from Pocos de Caldas, Brazil, which was described in Journal of Mineralogical and Petrological Sciences, vol.99, pp59-66, 2004 by us were collected using the above mentioned diffractometer eauipped the collimator.X-ray data are usually collected from an isolated grain of the relevant material and it is not necessary to consider the breadth of the incident rays. However, the grain on the thin section is not isolated but has the neighboring crystal … More grains around it. In order to avoid the extra reflected beams from the neighboring grains, focused rays should be utilized. For this reason, a collimator has been made using a flexible silica-glass tube of 0.2mm φ and has been tuned to focus the concerning specimen.In usual case, a whole set of the x-ray diffraction data of a single crystal is collected by varying the directions or tne inciaent x-rays and the diffracted x-rays. In the present case, however, the directions of those rays are very restricted because the slide glass under the specimen prohibits the propagation of the x-rays. To overcome the restrictions one of the writer and his coworkers developed a method which was described in Rigaku Denki Journal, Vol.25, Part1, pp3-9 (1994). According to this method, the white x-ray having the continuous energy spectra as the incident rays and the solid state detector which was enable to resolve the energy of the diffracted x-rays. The measured range in the reciprocal space was selected to the inside of a cone of which axis was normal to the surface of the thin section and its vertical angle was 21 degrees. The range was divided to 12,227 small areas and the diffracted x-rays from individual area were counted. 1540 significant diffracted intensities from relevant areas were obtained. Very large stress field seemed to remain in the crystals on thin section. The analysis of the measured data should be performed in near future Less