The knowledge of reaction pathways in the preparation of solids is usually rather scarce, which hinders synthesis planning and process control. This is particularly true for metastable compounds, which are a challenge for chemical synthesis, especially in the solid state. In situ studies can help in exploring the energy landscape around their local minimum by investigating formation and decomposition. Screening the multi-parameter space in synthetic chemistry is much more efficient using in as compared to ex situ methods. Studying solid–gas reactions in situ is demanding due to the oftentimes harsh conditions as for temperature and gas pressure. Examples are given for a variety of solids and applications, e.g., metal hydrides (hydrogen storage, hydrogenation – decomposition – desorption – recombination), intermetallics (heterogeneous catalysis), metal nitrides, nitride oxides and oxides (magnetic materials, photocatalysts). Many new metastable compounds with intriguing properties were discovered by such in situ studies in flowing or static gas atmosphere (H₂, Ar, NH₃, air) at elevated pressures and temperatures using a variety of in situ methods such as X-ray and neutron powder diffraction, thermal analysis, environmental scanning electron microscopy, Raman, NMR, UV-VIS and X-ray absorption fine structure spectroscopy. The potential of unravelling reaction pathways of solid–gas reactions for improving syntheses and controlling chemical processes is demonstrated.

The bibliography includes 48 references.

Based on a talk given at the 5th EUCHEMS Inorganic Chemistry Conference (EICC-5, Moscow, Russia, 2019).

固体制备中反应途径的知识通常相当匮乏，这阻碍了合成计划和过程控制。对于亚稳态化合物来说尤其如此，这对化学合成来说是一个挑战，尤其是在固态下。原位研究可以通过调查形成和分解来帮助探索局部最小值附近的能量景观。与非原位方法相比，使用in筛选合成化学中的多参数空间要有效得多。由于温度和气压等条件通常很苛刻，因此需要就地研究固气反应。给出了各种固体和应用的例子，例如、金属氢化物（储氢、加氢-分解-解吸-复合）、金属间化合物（多相催化）、金属氮化物、氮氧化物和氧化物（磁性材料、光催化剂）。许多具有有趣特性的新亚稳态化合物是通过在高压和高温下使用各种原位研究在流动或静态气体气氛（H ₂、Ar、NH _{3 、空气）中}进行的原位研究发现的X射线和中子粉末衍射、热分析、环境扫描电子显微镜、拉曼、核磁共振、UV-VIS和X射线吸收精细结构光谱等方法。证明了解开固-气反应的反应途径以改善合成和控制化学过程的潜力。

参考书目包括 48 篇参考文献。

基于在第五届 EUCHEMS 无机化学会议（EICC-5，莫斯科，俄罗斯，2019 年）上的演讲。