Chemical Reactions followed by in situ Neutron Powder Diffraction

Abstract

Abstract. In situ neutron powder diffraction is a very convenient tool for the investigation of chemical reactions, whenever crystalline solids are involved. It may give insight into reaction pathways, thus allowing for strategic synthesis planning, revealing particular intermediate steps and quantifying the reaction kinetics. Although the method is rather straightforward, one is bound to a small number of available neutron sources and the few sufficiently high intensity powder diffractometers there, most of which are briefly described herein. The high penetration depth of thermal neutrons allows for a large range of complex sample environments; however neutron absorption and parasitic scattering have to be carefully considered in the construction of dedicated in situ equipment. Some specific types of sample environment, specially designed for in situ neutron powder diffraction will be discussed such

Novel Methods for Sodium‐Ion Battery Materials

“…However, neutron diffraction (ND) gives complementary information in many regards, and may thus be used in cases where XRD is not well suited. For instance, the identification of light atoms in the presence of heavier atoms, the distinction of neighbor elements in the periodic table, and the determination of magnetic structures and thermal displacement parameters . Differently from X‐rays, which interact with an atom's electron cloud, neutrons can interact directly with the nucleus of the atom, and contribute to a much higher diffracted intensity.…”

“…For instance, the identification of light atoms in the presence of heavier atoms, the distinction of neighbor elements in the periodic table, and the determination of magnetic structures and thermal displacement parameters. [150,151] Differently from X-rays, which interact with an atom's electron cloud, neutrons can interact directly with the nucleus of the atom, and contribute to a much higher diffracted intensity. Neutron powder diffraction (NPD) can be used to determine the crystallographic positions of the chargecarrying sodium ions, the atomic displacement parameters, and the occupancies for NIBs.…”

Von der Natur des Wasserstoffs in Metallen

“…Selbst bei den gut untersuchten Kristallstrukturen gibt es Neues. Weiterentwickelte In-situ-Neutronenbeugungsmethoden 14) machen neue Strukturuntersuchungen möglich, die extreme Bedingungen und geringe Wasserstoffkonzentrationen mit Realzeitstudien der Wasserstoffaufnahme kombinieren. Beispiele sind α-PdD 0,038(4) bei 177 °C und 3 bar Deuteriumgasdruck 15) sowie der Nachweis der Tetraederlückenbesetzung bis zu 3,3(3) % bei 69 bar.…”

“…16) Große Aufmerksamkeit bekommen auch palladiumreiche intermetallische Phasen, die wasser stoff in du zier te Ordnungsphänomene zeigen oder katalytisch wirken, wenn Hauptgruppenmetalle das Palladium ersetzen. 14,17,18) Palladiumhydrid zeigt: In der Regel entwickelt sich Erkenntnis in der Wissenschaft nicht linear. Manchmal gibt es Stillstand, der sich aber auflöst, sobald eine neue Theorie oder eine experimentelle Untersuchungsmethode zur Verfügung steht.…”

In situ Investigations on the Formation and Decomposition of KSiH3 and CsSiH3

“…In situ neutron diffraction has shown a huge potential for unraveling reaction pathways of solid‐gas reactions in general, and for Zintl phases in particular , . The huge advantage of neutron scattering over other solid‐state probes is the low neutron absorption of many materials.…”