同步輻射粉末繞射技術－動態結構分析

Synchrotron Powder X-ray Diffraction: Dynamic structural analysis

陳柏豪(Bo-Hao Chen) ； 黃繼億(Chi-Yi Huang) ； 黃睿哲(Jui-Che Huang) ； 張仲凱(Chung-Kai Chang) ； 賴彥仲(Yen-Chung Lai) ； 莊裕鈞(Yu-Chun Chuang)

《真空科技》 32卷4期 (2019/12) Pp. 5-10

摘要

高解析度粉末繞射實驗，針對｢非常態環境下晶體結構動力學研究｣的發展有著顯著的影響力。實驗站的設計也著重於協助各種樣態樣品的量測，不僅提供高效率的量測方式，同時研發具有高解析度的多晶體分析儀（Multi-Crystal Analyzer, MCA），令其兼具傳統與創新。除此之外，諸多儀器設備之間也引進自動化控制，透過三種強大的程式語言（SPEC, EPICS與Python），整合數據收集與樣品環境控制，大幅提升數據收集的效率，且有效避免人為錯誤確保實驗安全。大量的高解析度粉末繞射數據收集後，可利用批次結構精算方法（Sequential Rietveld Refinement），進行結構動力學分析，成功的證明AgI樣品於溫度變化的過程中相變化的趨勢。穩定的實驗環境變化與高效率的數據收集，將可提供有用的結構信息，應用於新穎領域的發展。

並列摘要

High-resolution powder X-ray diffraction is an ideal tool to study the molecular structure and packing diagram at non-ambient sample environments and has been developed for several years. The Taiwan Photon Source 19A beamline (TPS 19A) was designed not only for studying static structure but also structure dynamics. For structure determination, a new fine-tunable mechanism design for multi-crystal analyzer (MCA) was included, which makes alignment of analyzer crystal more reliable and precise. The diffraction peak resolution was dominated by the Darwin width of Si(111) analyzing crystal and can be reached to 0.005 degree. It helps to overcome the intrinsic peak overlapping problem in powder diffraction experiment. And the well extracted intensity of induvial diffraction signal contribute to structural model building. However, evaluation of a large numbers of powder diffraction patterns measured as a function of an external perturbation is still time consuming. For structure dynamics, the MYTHEN 24K provides fast data acquisition during in-situ XRD experiment. A new analytic refinement strategy, so-called sequential Rietveld refinement, was introduced. The phase transformations of AgI during temperature dependent powder diffraction experiment were clearly demonstrated. It shows very smooth structure change and can provide useful structural information after applying external perturbations.