The direct derivation (DD) method is a technique for quantitative phase analysis (QPA). It can be characterized by the use of the total sums of scattered/diffracted intensities from individual components as the observed data. The crystal structure parameters are required when we calculate the intensities of reflections or diffraction patterns. Intensity can, however, be calculated only with the chemical composition data if it is not of individual reflections but of a total sum of diffracted/scattered intensities for that material. Furthermore, it can be given in a form of the scattered intensity per unit weight. Therefore, we can calculate the weight proportion of a component material by dividing the total sum of observed scattered/diffracted intensities by the scattered intensity per unit weight. The chemical composition data of samples under investigation are known in almost all cases at the stage of QPA. Thus, a technical problem is how to separate the observed diffraction pattern of a mixture into individual component patterns. Various pattern decomposition techniques currently available can be used for separating the pattern of a mixture. In this report, the theoretical background of the DD method and various techniques for pattern decompositions are reviewed along with the examples of applications.

中文翻译：

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直接推导法的回顾：用观察到的强度和化学成分数据进行定量相分析

直接推导 (DD) 方法是一种用于定量相位分析 (QPA) 的技术。它可以通过使用来自各个分量的散射/衍射强度的总和作为观察数据来表征。当我们计算反射或衍射图案的强度时，需要晶体结构参数。但是，如果强度不是单个反射，而是该材料的衍射/散射强度的总和，则只能使用化学成分数据计算强度。此外，它可以以每单位重量的散射强度的形式给出。因此，我们可以通过将观察到的散射/衍射强度的总和除以每单位重量的散射强度来计算成分材料的重量比例。在 QPA 阶段，几乎所有情况下都知道被调查样品的化学成分数据。因此，一个技术问题是如何将观察到的混合物的衍射图案分离成单独的成分图案。当前可用的各种模式分解技术可用于分离混合物的模式。在本报告中，将回顾 DD 方法的理论背景和模式分解的各种技术以及应用示例。