In situ and operando characterization of materials and devices in many cases provide key information towards understanding properties and function. Remarkable advances in analytical tools have been made in recent years, with in situ and operando characterization continually developing to exploit the new capabilities. In situ and operando characterization relies on complex sample environment systems, necessitating careful development of experimental protocols to optimize accuracy and reliability of the results.

Functional materials are of great importance for the development of new technologies. Functional materials include those used for technologies to convert, store, transport and delivery energy, materials in biological and health applications, as nanostructured polymers and in construction. Environmental concerns direct a broad range of advanced technologies towards sustainable operation and higher efficiencies. Functional materials play a pivotal role and their characterization is at the heart of functional materials research. The relation between structure, dynamics and function is essential for the future design of materials with improved performance characteristics.

Understanding the working mechanism and structure function relationship at the atomic and molecular scale is the key to advancing new technologies. Essential is the characterization of materials during operation, and in situ and operando studies are necessary in functional materials research. The in situ technique, often applied to materials at equilibrium, has been extended in recent years to operando studies, where the materials are studied under non-equilibrium real-time conditions.

In situ and operando experiments are demanding but new laboratory experiments and synchrotron/neutron facilities provide opportunity for such studies as new sample environments and new generation neutron and X-ray sources in combination with faster instrumentation are being developed. These capabilities will hopefully stimulate interest in the use of the large scale neutron and X-ray facilities around the world.

atomic layer deposition chemical vapor deposition (CVD) (deposition) molecular beam epitaxy (MBE) physical vapor deposition (PVD) plasma deposition plasma-enhanced CVD (PECVD) (deposition) sputtering