Svensson S O, Birch J, Müller H, Kvick A
ESRF, BP 220, 38043 Grenoble CEDEX, France.
J Synchrotron Radiat. 1997 Mar 1;4(Pt 2):83-94. doi: 10.1107/S0909049597000265.
A kinetic study of the solid-state polymerization of disulfur dinitride (S2N2) to polysulfur nitride [(SN)x] has been performed, combining monochromatic high-energy (lambda = 0.3263 A) synchrotron radiation X-ray powder diffraction, a large-area (ø = 220 mm) CCD-based X-ray image-intensifier detector and Rietveld refinement. Recently developed techniques for detector calibration and reduction of two-dimensional images to one-dimensional diffraction patterns have been employed for data processing/analysis. Good fits were obtained after Rietveld refinement [Rp = 8.4%, wRp = 9.4%, sin(theta(max))/lambda = 0.585 A(-1)] of diffraction patterns of S2N2 from images with 2 s exposure time. The solid-state polymerization of S2N2 to (SN)x, was followed at a maximum rate of two diffraction images per minute. Scale factors and cell parameters for S2N2 and beta-(SN), as functions of time were readily obtained after Rietveld refinement of the diffraction patterns obtained from each individual image throughout the polymerization. The polymerization was preceded by a lattice distortion of S2N2, and at 50% conversion the a axis had decreased by about 1% and the c axis had increased about 1%. The polymerization yielded not only the expected polymer beta-(SN)x, but also a small amount of a compound that could be another phase of (SN)x.
结合单色高能（λ = 0.3263 Å）同步辐射X射线粉末衍射、大面积（ø = 220 mm）基于电荷耦合器件（CCD）的X射线图像增强探测器以及Rietveld精修，对二氮化二硫（S2N2）固态聚合成聚氮化硫[(SN)x]进行了动力学研究。数据处理/分析采用了最近开发的探测器校准技术以及将二维图像转换为一维衍射图谱的技术。对曝光时间为2 s的图像中S2N2的衍射图谱进行Rietveld精修[Rp = 8.4%，wRp = 9.4%，sin(θ(max))/λ = 0.585 Å-1]后，得到了良好的拟合结果。以每分钟最多两张衍射图像的速率对S2N2聚合成(SN)x的过程进行了跟踪。在对整个聚合过程中从每个单独图像获得的衍射图谱进行Rietveld精修后，很容易得到S2N2和β-(SN)的比例因子和晶胞参数随时间的变化情况。聚合之前S2N2存在晶格畸变，在转化率达到50%时，a轴减少了约1%，c轴增加了约1%。聚合不仅生成了预期的聚合物β-(SN)x，还生成了少量可能是(SN)x另一相的化合物。
