Apparatus for rapid analysis of wide-angle X-ray diffraction patterns at high temperatures

研制了一种能在高温下从无机粉末晶体中快速记录x射线衍射图样的装置。该仪器是建立在一个新设计的圆柱形位置敏感气体探测器上的，其角度覆盖范围为120度弧。探测器在阳极使用薄金属刀片，并在自淬流光模式下运行。阳极半径可达250mm，可与大多数高温试样室兼容。延迟线读出条形阴极的位置信号，给出0.05弧度的角分辨率。该探测器安装在一个两轴测角仪上，用于检测静止粉末试样的衍射图样。为了抑制被测图样中反射线的展宽，狭缝系统限制了入射到平面样品上的x射线的角发散。采集在多通道分析仪存储器中的数据被读入计算机，由模式拟合程序进行分析。用标准刚玉试样进行的测试证明了该装置的速度和精度：与标准θ - 2 θ扫描方法相比，在1/80的记录时间内获得了分辨率更高的衍射图案。实验图与计算图拟合较好，得到的结构参数与已发表的数据吻合较好。该装置在高温工程中的实用性已在一个应用中得到证明，其中氧化铋中的δ相的结构在784摄氏度下被精炼。

An apparatus has been developed which permits rapid recording of Xray diffraction patterns from inorganic powder crystals at high temperatures. The apparatus is built on a newly designed cylindrical position sensitive gas detector with an angular coverage of 120 degree of arc. The detector uses a thin metal blade in the anode and is operated in the selfquenching streamer mode. The anode radius is as large as 250mm to be compatible with most high-temperature specimen chambers. A delay line reads out the position signal from the strip cathodes to give an angular resolution of 0.05 degree of arc. The detector is mounted on a two-axis goniometer to detect a diffraction pattern from a stationary powder specimen. To suppress the broadening of reflection lines in the detected pattern, a slit system limits the angular divergence of X-rays incident on the planar specimen. The data, collected in a multi-channel analyzer memory, is read into a computer for analysis by a pattern fitting program. A test made with a standard corundom specimen demonstrates the speed and precision of the apparatus: a diffraction pattern substantially better in resolution has been obtained in a recording time of 1/80 as compared with a standard theta-two theta scanning method. The experimental pattern has been fitted well with the calculated one to give structural parameters in good agreement with the published data for this material. The usefulness of the apparatus in high-temperature works has been shown in an application, where the structure of the delta phase in bismuth oxide is refined at 784 degree Celsius.