It is obvious and well known that, when starting studies on a given sample, it is necessary to be sure of the chemical and phase composition of the sample. The most ideal method is to verify this by X-ray (or neutron) diffraction and subsequent structural analysis. Such initial analysis must use the well-known set of assumptions based on 100 years of X-ray diffraction studies. Without the use of these assumptions or rules, the subsequent results of any studies will not be valuable and may be erroneous. The most important rule is that the diffraction pattern is a kind of fingerprint of the given crystal/compound. Thus, the second rule is that the diffraction pattern of the mixture of phases is a simple sum of diffraction patters from the components.

中文翻译：

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对“镁铁基双钙钛矿的介电、光学和磁性行为”的评论 [ECS J. Solid State Sci.技术。 , 11, 113003 (2022)]

显然且众所周知，当开始对给定样品进行研究时，有必要确定样品的化学和物相组成。最理想的方法是通过X射线（或中子）衍射和随后的结构分析来验证这一点。此类初始分析必须使用基于 100 年 X 射线衍射研究的众所周知的一组假设。如果不使用这些假设或规则，任何研究的后续结果都将没有价值，并且可能是错误的。最重要的规则是衍射图样是一种指纹给定的晶体/化合物。因此，第二条规则是混合相的衍射图案是各成分的衍射图案的简单总和。